Set 2.4 release date

(cherry picked from commit bc4b7521f4)

.github/STALE-BOT.md

@@ -3,7 +3,7 @@
 - Thanks for your contribution!
 - To remove the stale label, just leave a new comment.
 - _How to find the right people to ping?_ → [`git blame`](https://git-scm.com/docs/git-blame) to the rescue! (or GitHub's history and blame buttons.)
-- You can always ask for help on [our Discourse Forum](https://discourse.nixos.org/) or on the [#nixos IRC channel](https://webchat.freenode.net/#nixos).
+- You can always ask for help on [our Discourse Forum](https://discourse.nixos.org/) or on [Matrix - #nix:nixos.org](https://matrix.to/#/#nix:nixos.org).
 
 ## Suggestions for PRs
 

.github/workflows/test.yml

@@ -4,14 +4,67 @@ on:
   push:
 jobs:
   tests:
+    needs: [check_cachix]
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest]
+    runs-on: ${{ matrix.os }}
+
+    steps:
+    - uses: actions/checkout@v2.3.4
+      with:
+        fetch-depth: 0
+    - uses: cachix/install-nix-action@v14
+    - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
+    - uses: cachix/cachix-action@v10
+      if: needs.check_cachix.outputs.secret == 'true'
+      with:
+        name: '${{ env.CACHIX_NAME }}'
+        signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
+        authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+    - run: nix-build -A checks.$(nix-instantiate --eval -E '(builtins.currentSystem)')
+  check_cachix:
+    name: Cachix secret present for installer tests
+    runs-on: ubuntu-latest
+    outputs:
+      secret: ${{ steps.secret.outputs.secret }}
+    steps:
+      - name: Check for Cachix secret
+        id: secret
+        env:
+          _CACHIX_SECRETS: ${{ secrets.CACHIX_SIGNING_KEY }}${{ secrets.CACHIX_AUTH_TOKEN }}
+        run: echo "::set-output name=secret::${{ env._CACHIX_SECRETS != '' }}"
+  installer:
+    needs: [tests, check_cachix]
+    if: github.event_name == 'push' && needs.check_cachix.outputs.secret == 'true'
+    runs-on: ubuntu-latest
+    outputs:
+      installerURL: ${{ steps.prepare-installer.outputs.installerURL }}
+    steps:
+    - uses: actions/checkout@v2.3.4
+      with:
+        fetch-depth: 0
+    - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
+    - uses: cachix/install-nix-action@v14
+    - uses: cachix/cachix-action@v10
+      with:
+        name: '${{ env.CACHIX_NAME }}'
+        signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
+        authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+    - id: prepare-installer
+      run: scripts/prepare-installer-for-github-actions
+  installer_test:
+    needs: [installer, check_cachix]
+    if: github.event_name == 'push' && needs.check_cachix.outputs.secret == 'true'
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
     runs-on: ${{ matrix.os }}
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v2.3.4
+    - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
+    - uses: cachix/install-nix-action@v14
       with:
-        fetch-depth: 0
-    - uses: cachix/install-nix-action@v12
-    #- run: nix flake check
-    - run: nix-build -A checks.$(if [[ `uname` = Linux ]]; then echo x86_64-linux; else echo x86_64-darwin; fi)
+        install_url: '${{needs.installer.outputs.installerURL}}'
+        install_options: "--tarball-url-prefix https://${{ env.CACHIX_NAME }}.cachix.org/serve"
+    - run: nix-instantiate -E 'builtins.currentTime' --eval

.gitignore

@@ -15,6 +15,7 @@ perl/Makefile.config
 /doc/manual/*.1
 /doc/manual/*.5
 /doc/manual/*.8
+/doc/manual/generated/*
 /doc/manual/nix.json
 /doc/manual/conf-file.json
 /doc/manual/builtins.json
@@ -56,9 +57,6 @@ perl/Makefile.config
 
 /src/nix-prefetch-url/nix-prefetch-url
 
-# /src/nix-daemon/
-/src/nix-daemon/nix-daemon
-
 /src/nix-collect-garbage/nix-collect-garbage
 
 # /src/nix-channel/
@@ -76,12 +74,12 @@ perl/Makefile.config
 # /tests/
 /tests/test-tmp
 /tests/common.sh
-/tests/dummy
 /tests/result*
 /tests/restricted-innocent
 /tests/shell
 /tests/shell.drv
 /tests/config.nix
+/tests/ca/config.nix
 
 # /tests/lang/
 /tests/lang/*.out

Makefile

@@ -4,6 +4,7 @@ makefiles = \
   src/libutil/local.mk \
   src/libutil/tests/local.mk \
   src/libstore/local.mk \
+  src/libstore/tests/local.mk \
   src/libfetchers/local.mk \
   src/libmain/local.mk \
   src/libexpr/local.mk \
@@ -12,6 +13,8 @@ makefiles = \
   src/resolve-system-dependencies/local.mk \
   scripts/local.mk \
   misc/bash/local.mk \
+  misc/fish/local.mk \
+  misc/zsh/local.mk \
   misc/systemd/local.mk \
   misc/launchd/local.mk \
   misc/upstart/local.mk \
@@ -31,4 +34,4 @@ endif
 
 include mk/lib.mk
 
-GLOBAL_CXXFLAGS += -g -Wall -include config.h -std=c++17
+GLOBAL_CXXFLAGS += -g -Wall -include config.h -std=c++17 -I src

Makefile.config.in

@@ -1,3 +1,4 @@
+HOST_OS = @host_os@
 AR = @AR@
 BDW_GC_LIBS = @BDW_GC_LIBS@
 BOOST_LDFLAGS = @BOOST_LDFLAGS@
@@ -9,13 +10,14 @@ CXXFLAGS = @CXXFLAGS@
 EDITLINE_LIBS = @EDITLINE_LIBS@
 ENABLE_S3 = @ENABLE_S3@
 GTEST_LIBS = @GTEST_LIBS@
+HAVE_LIBCPUID = @HAVE_LIBCPUID@
 HAVE_SECCOMP = @HAVE_SECCOMP@
 LDFLAGS = @LDFLAGS@
 LIBARCHIVE_LIBS = @LIBARCHIVE_LIBS@
 LIBBROTLI_LIBS = @LIBBROTLI_LIBS@
 LIBCURL_LIBS = @LIBCURL_LIBS@
-LIBLZMA_LIBS = @LIBLZMA_LIBS@
 OPENSSL_LIBS = @OPENSSL_LIBS@
+LIBSECCOMP_LIBS = @LIBSECCOMP_LIBS@
 PACKAGE_NAME = @PACKAGE_NAME@
 PACKAGE_VERSION = @PACKAGE_VERSION@
 SHELL = @bash@

README.md

@@ -28,7 +28,8 @@ build nix from source with nix-build or how to get a development environment.
 - [Nix manual](https://nixos.org/nix/manual)
 - [Nix jobsets on hydra.nixos.org](https://hydra.nixos.org/project/nix)
 - [NixOS Discourse](https://discourse.nixos.org/)
-- [IRC - #nixos on freenode.net](irc://irc.freenode.net/#nixos)
+- [Matrix - #nix:nixos.org](https://matrix.to/#/#nix:nixos.org)
+- [IRC - #nixos on libera.chat](irc://irc.libera.chat/#nixos)
 
 ## License
 

boehmgc-coroutine-sp-fallback.diff

@@ -0,0 +1,42 @@
+diff --git a/pthread_stop_world.c b/pthread_stop_world.c
+index 1cee6a0b..46c3acd9 100644
+--- a/pthread_stop_world.c
++++ b/pthread_stop_world.c
+@@ -674,6 +674,8 @@ GC_INNER void GC_push_all_stacks(void)
+     struct GC_traced_stack_sect_s *traced_stack_sect;
+     pthread_t self = pthread_self();
+     word total_size = 0;
++    size_t stack_limit;
++    pthread_attr_t pattr;
+ 
+     if (!EXPECT(GC_thr_initialized, TRUE))
+       GC_thr_init();
+@@ -723,6 +725,28 @@ GC_INNER void GC_push_all_stacks(void)
+           hi = p->altstack + p->altstack_size;
+           /* FIXME: Need to scan the normal stack too, but how ? */
+           /* FIXME: Assume stack grows down */
++        } else {
++          if (pthread_getattr_np(p->id, &pattr)) {
++            ABORT("GC_push_all_stacks: pthread_getattr_np failed!");
++          }
++          if (pthread_attr_getstacksize(&pattr, &stack_limit)) {
++            ABORT("GC_push_all_stacks: pthread_attr_getstacksize failed!");
++          }
++          // When a thread goes into a coroutine, we lose its original sp until
++          // control flow returns to the thread.
++          // While in the coroutine, the sp points outside the thread stack,
++          // so we can detect this and push the entire thread stack instead,
++          // as an approximation.
++          // We assume that the coroutine has similarly added its entire stack.
++          // This could be made accurate by cooperating with the application
++          // via new functions and/or callbacks.
++          #ifndef STACK_GROWS_UP
++            if (lo >= hi || lo < hi - stack_limit) { // sp outside stack
++              lo = hi - stack_limit;
++            }
++          #else
++          #error "STACK_GROWS_UP not supported in boost_coroutine2 (as of june 2021), so we don't support it in Nix."
++          #endif
+         }
+         GC_push_all_stack_sections(lo, hi, traced_stack_sect);
+ #       ifdef STACK_GROWS_UP

config/config.guess

@@ -1,8 +1,8 @@
 #! /bin/sh
 # Attempt to guess a canonical system name.
-#   Copyright 1992-2020 Free Software Foundation, Inc.
+#   Copyright 1992-2021 Free Software Foundation, Inc.
 
-timestamp='2020-11-19'
+timestamp='2021-01-25'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -50,7 +50,7 @@ version="\
 GNU config.guess ($timestamp)
 
 Originally written by Per Bothner.
-Copyright 1992-2020 Free Software Foundation, Inc.
+Copyright 1992-2021 Free Software Foundation, Inc.
 
 This is free software; see the source for copying conditions.  There is NO
 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE."
@@ -188,10 +188,9 @@ case "$UNAME_MACHINE:$UNAME_SYSTEM:$UNAME_RELEASE:$UNAME_VERSION" in
 	#
 	# Note: NetBSD doesn't particularly care about the vendor
 	# portion of the name.  We always set it to "unknown".
-	sysctl="sysctl -n hw.machine_arch"
 	UNAME_MACHINE_ARCH=$( (uname -p 2>/dev/null || \
-	    "/sbin/$sysctl" 2>/dev/null || \
-	    "/usr/sbin/$sysctl" 2>/dev/null || \
+	    /sbin/sysctl -n hw.machine_arch 2>/dev/null || \
+	    /usr/sbin/sysctl -n hw.machine_arch 2>/dev/null || \
 	    echo unknown))
 	case "$UNAME_MACHINE_ARCH" in
 	    aarch64eb) machine=aarch64_be-unknown ;;
@@ -996,6 +995,9 @@ EOF
     k1om:Linux:*:*)
 	echo "$UNAME_MACHINE"-unknown-linux-"$LIBC"
 	exit ;;
+    loongarch32:Linux:*:* | loongarch64:Linux:*:* | loongarchx32:Linux:*:*)
+	echo "$UNAME_MACHINE"-unknown-linux-"$LIBC"
+	exit ;;
     m32r*:Linux:*:*)
 	echo "$UNAME_MACHINE"-unknown-linux-"$LIBC"
 	exit ;;
@@ -1084,7 +1086,7 @@ EOF
     ppcle:Linux:*:*)
 	echo powerpcle-unknown-linux-"$LIBC"
 	exit ;;
-    riscv32:Linux:*:* | riscv64:Linux:*:*)
+    riscv32:Linux:*:* | riscv32be:Linux:*:* | riscv64:Linux:*:* | riscv64be:Linux:*:*)
 	echo "$UNAME_MACHINE"-unknown-linux-"$LIBC"
 	exit ;;
     s390:Linux:*:* | s390x:Linux:*:*)
@@ -1480,8 +1482,8 @@ EOF
     i*86:rdos:*:*)
 	echo "$UNAME_MACHINE"-pc-rdos
 	exit ;;
-    i*86:AROS:*:*)
-	echo "$UNAME_MACHINE"-pc-aros
+    *:AROS:*:*)
+	echo "$UNAME_MACHINE"-unknown-aros
 	exit ;;
     x86_64:VMkernel:*:*)
 	echo "$UNAME_MACHINE"-unknown-esx

config/config.sub

@@ -1,8 +1,8 @@
 #! /bin/sh
 # Configuration validation subroutine script.
-#   Copyright 1992-2020 Free Software Foundation, Inc.
+#   Copyright 1992-2021 Free Software Foundation, Inc.
 
-timestamp='2020-12-02'
+timestamp='2021-01-08'
 
 # This file is free software; you can redistribute it and/or modify it
 # under the terms of the GNU General Public License as published by
@@ -67,7 +67,7 @@ Report bugs and patches to <config-patches@gnu.org>."
 version="\
 GNU config.sub ($timestamp)
 
-Copyright 1992-2020 Free Software Foundation, Inc.
+Copyright 1992-2021 Free Software Foundation, Inc.
 
 This is free software; see the source for copying conditions.  There is NO
 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE."
@@ -1185,6 +1185,7 @@ case $cpu-$vendor in
 			| k1om \
 			| le32 | le64 \
 			| lm32 \
+			| loongarch32 | loongarch64 | loongarchx32 \
 			| m32c | m32r | m32rle \
 			| m5200 | m68000 | m680[012346]0 | m68360 | m683?2 | m68k \
 			| m6811 | m68hc11 | m6812 | m68hc12 | m68hcs12x \
@@ -1229,7 +1230,7 @@ case $cpu-$vendor in
 			| powerpc | powerpc64 | powerpc64le | powerpcle | powerpcspe \
 			| pru \
 			| pyramid \
-			| riscv | riscv32 | riscv64 \
+			| riscv | riscv32 | riscv32be | riscv64 | riscv64be \
 			| rl78 | romp | rs6000 | rx \
 			| s390 | s390x \
 			| score \
@@ -1682,11 +1683,14 @@ fi
 
 # Now, validate our (potentially fixed-up) OS.
 case $os in
-	# Sometimes we do "kernel-abi", so those need to count as OSes.
+	# Sometimes we do "kernel-libc", so those need to count as OSes.
 	musl* | newlib* | uclibc*)
 		;;
-	# Likewise for "kernel-libc"
-	eabi | eabihf | gnueabi | gnueabihf)
+	# Likewise for "kernel-abi"
+	eabi* | gnueabi*)
+		;;
+	# VxWorks passes extra cpu info in the 4th filed.
+	simlinux | simwindows | spe)
 		;;
 	# Now accept the basic system types.
 	# The portable systems comes first.
@@ -1750,6 +1754,8 @@ case $kernel-$os in
 		;;
 	kfreebsd*-gnu* | kopensolaris*-gnu*)
 		;;
+	vxworks-simlinux | vxworks-simwindows | vxworks-spe)
+		;;
 	nto-qnx*)
 		;;
 	os2-emx)

configure.ac

@@ -1,4 +1,4 @@
-AC_INIT(nix, m4_esyscmd([bash -c "echo -n $(cat ./.version)$VERSION_SUFFIX"]))
+AC_INIT([nix],[m4_esyscmd(bash -c "echo -n $(cat ./.version)$VERSION_SUFFIX")])
 AC_CONFIG_MACRO_DIRS([m4])
 AC_CONFIG_SRCDIR(README.md)
 AC_CONFIG_AUX_DIR(config)
@@ -9,8 +9,7 @@ AC_PROG_SED
 AC_CANONICAL_HOST
 AC_MSG_CHECKING([for the canonical Nix system name])
 
-AC_ARG_WITH(system, AC_HELP_STRING([--with-system=SYSTEM],
-  [Platform identifier (e.g., `i686-linux').]),
+AC_ARG_WITH(system, AS_HELP_STRING([--with-system=SYSTEM],[Platform identifier (e.g., `i686-linux').]),
   [system=$withval],
   [case "$host_cpu" in
      i*86)
@@ -33,14 +32,6 @@ AC_ARG_WITH(system, AC_HELP_STRING([--with-system=SYSTEM],
         system="$machine_name-`echo $host_os | "$SED" -e's/@<:@0-9.@:>@*$//g'`";;
    esac])
 
-sys_name=$(uname -s | tr 'A-Z ' 'a-z_')
-
-case $sys_name in
-    cygwin*)
-        sys_name=cygwin
-        ;;
-esac
-
 AC_MSG_RESULT($system)
 AC_SUBST(system)
 AC_DEFINE_UNQUOTED(SYSTEM, ["$system"], [platform identifier ('cpu-os')])
@@ -64,10 +55,12 @@ AC_SYS_LARGEFILE
 
 # Solaris-specific stuff.
 AC_STRUCT_DIRENT_D_TYPE
-if test "$sys_name" = sunos; then
+case "$host_os" in
+  solaris*)
     # Solaris requires -lsocket -lnsl for network functions
-    LIBS="-lsocket -lnsl $LIBS"
-fi
+    LDFLAGS="-lsocket -lnsl $LDFLAGS"
+    ;;
+esac
 
 
 # Check for pubsetbuf.
@@ -127,8 +120,7 @@ NEED_PROG(jq, jq)
 AC_SUBST(coreutils, [$(dirname $(type -p cat))])
 
 
-AC_ARG_WITH(store-dir, AC_HELP_STRING([--with-store-dir=PATH],
-  [path of the Nix store (defaults to /nix/store)]),
+AC_ARG_WITH(store-dir, AS_HELP_STRING([--with-store-dir=PATH],[path of the Nix store (defaults to /nix/store)]),
   storedir=$withval, storedir='/nix/store')
 AC_SUBST(storedir)
 
@@ -152,13 +144,12 @@ int main() {
 }]])], GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC=no, GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC=yes)
 AC_MSG_RESULT($GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC)
 if test "x$GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC" = xyes; then
-    LIBS="-latomic $LIBS"
+    LDFLAGS="-latomic $LDFLAGS"
 fi
 
 PKG_PROG_PKG_CONFIG
 
-AC_ARG_ENABLE(shared, AC_HELP_STRING([--enable-shared],
-  [Build shared libraries for Nix [default=yes]]),
+AC_ARG_ENABLE(shared, AS_HELP_STRING([--enable-shared],[Build shared libraries for Nix [default=yes]]),
   shared=$enableval, shared=yes)
 if test "$shared" = yes; then
   AC_SUBST(BUILD_SHARED_LIBS, 1, [Whether to build shared libraries.])
@@ -172,11 +163,6 @@ fi
 PKG_CHECK_MODULES([OPENSSL], [libcrypto], [CXXFLAGS="$OPENSSL_CFLAGS $CXXFLAGS"])
 
 
-# Look for libbz2, a required dependency.
-AC_CHECK_LIB([bz2], [BZ2_bzWriteOpen], [true],
-  [AC_MSG_ERROR([Nix requires libbz2, which is part of bzip2.  See https://sourceware.org/bzip2/.])])
-AC_CHECK_HEADERS([bzlib.h], [true],
-  [AC_MSG_ERROR([Nix requires libbz2, which is part of bzip2.  See https://sourceware.org/bzip2/.])])
 # Checks for libarchive
 PKG_CHECK_MODULES([LIBARCHIVE], [libarchive >= 3.1.2], [CXXFLAGS="$LIBARCHIVE_CFLAGS $CXXFLAGS"])
 # Workaround until https://github.com/libarchive/libarchive/issues/1446 is fixed
@@ -205,45 +191,45 @@ PKG_CHECK_MODULES([EDITLINE], [libeditline], [CXXFLAGS="$EDITLINE_CFLAGS $CXXFLA
 # Look for libsodium, an optional dependency.
 PKG_CHECK_MODULES([SODIUM], [libsodium], [CXXFLAGS="$SODIUM_CFLAGS $CXXFLAGS"])
 
-# Look for liblzma, a required dependency.
-PKG_CHECK_MODULES([LIBLZMA], [liblzma], [CXXFLAGS="$LIBLZMA_CFLAGS $CXXFLAGS"])
-AC_CHECK_LIB([lzma], [lzma_stream_encoder_mt],
-  [AC_DEFINE([HAVE_LZMA_MT], [1], [xz multithreaded compression support])])
-
-# Look for zlib, a required dependency.
-PKG_CHECK_MODULES([ZLIB], [zlib], [CXXFLAGS="$ZLIB_CFLAGS $CXXFLAGS"])
-AC_CHECK_HEADER([zlib.h],[:],[AC_MSG_ERROR([could not find the zlib.h header])])
-LDFLAGS="-lz $LDFLAGS"
-
 # Look for libbrotli{enc,dec}.
 PKG_CHECK_MODULES([LIBBROTLI], [libbrotlienc libbrotlidec], [CXXFLAGS="$LIBBROTLI_CFLAGS $CXXFLAGS"])
 
+# Look for libcpuid.
+if test "$machine_name" = "x86_64"; then
+  PKG_CHECK_MODULES([LIBCPUID], [libcpuid], [CXXFLAGS="$LIBCPUID_CFLAGS $CXXFLAGS"])
+  have_libcpuid=1
+  AC_DEFINE([HAVE_LIBCPUID], [1], [Use libcpuid])
+fi
+AC_SUBST(HAVE_LIBCPUID, [$have_libcpuid])
+
 
 # Look for libseccomp, required for Linux sandboxing.
-if test "$sys_name" = linux; then
-  AC_ARG_ENABLE([seccomp-sandboxing],
-                AC_HELP_STRING([--disable-seccomp-sandboxing],
-                               [Don't build support for seccomp sandboxing (only recommended if your arch doesn't support libseccomp yet!)]
-                              ))
-  if test "x$enable_seccomp_sandboxing" != "xno"; then
-    PKG_CHECK_MODULES([LIBSECCOMP], [libseccomp],
-                      [CXXFLAGS="$LIBSECCOMP_CFLAGS $CXXFLAGS"])
-    have_seccomp=1
-    AC_DEFINE([HAVE_SECCOMP], [1], [Whether seccomp is available and should be used for sandboxing.])
-  else
+case "$host_os" in
+  linux*)
+    AC_ARG_ENABLE([seccomp-sandboxing],
+                  AS_HELP_STRING([--disable-seccomp-sandboxing],[Don't build support for seccomp sandboxing (only recommended if your arch doesn't support libseccomp yet!)
+                                ]))
+    if test "x$enable_seccomp_sandboxing" != "xno"; then
+      PKG_CHECK_MODULES([LIBSECCOMP], [libseccomp],
+                        [CXXFLAGS="$LIBSECCOMP_CFLAGS $CXXFLAGS"])
+      have_seccomp=1
+      AC_DEFINE([HAVE_SECCOMP], [1], [Whether seccomp is available and should be used for sandboxing.])
+    else
+      have_seccomp=
+    fi
+    ;;
+  *)
     have_seccomp=
-  fi
-else
-  have_seccomp=
-fi
+    ;;
+esac
 AC_SUBST(HAVE_SECCOMP, [$have_seccomp])
 
 
 # Look for aws-cpp-sdk-s3.
 AC_LANG_PUSH(C++)
 AC_CHECK_HEADERS([aws/s3/S3Client.h],
-  [AC_DEFINE([ENABLE_S3], [1], [Whether to enable S3 support via aws-sdk-cpp.])
-  enable_s3=1], [enable_s3=])
+  [AC_DEFINE([ENABLE_S3], [1], [Whether to enable S3 support via aws-sdk-cpp.]) enable_s3=1],
+  [AC_DEFINE([ENABLE_S3], [0], [Whether to enable S3 support via aws-sdk-cpp.]) enable_s3=])
 AC_SUBST(ENABLE_S3, [$enable_s3])
 AC_LANG_POP(C++)
 
@@ -256,8 +242,7 @@ fi
 
 
 # Whether to use the Boehm garbage collector.
-AC_ARG_ENABLE(gc, AC_HELP_STRING([--enable-gc],
-  [enable garbage collection in the Nix expression evaluator (requires Boehm GC) [default=yes]]),
+AC_ARG_ENABLE(gc, AS_HELP_STRING([--enable-gc],[enable garbage collection in the Nix expression evaluator (requires Boehm GC) [default=yes]]),
   gc=$enableval, gc=yes)
 if test "$gc" = yes; then
   PKG_CHECK_MODULES([BDW_GC], [bdw-gc])
@@ -271,11 +256,12 @@ PKG_CHECK_MODULES([GTEST], [gtest_main])
 
 
 # documentation generation switch
-AC_ARG_ENABLE(doc-gen, AC_HELP_STRING([--disable-doc-gen],
-  [disable documentation generation]),
+AC_ARG_ENABLE(doc-gen, AS_HELP_STRING([--disable-doc-gen],[disable documentation generation]),
   doc_generate=$enableval, doc_generate=yes)
 AC_SUBST(doc_generate)
 
+# Look for lowdown library.
+PKG_CHECK_MODULES([LOWDOWN], [lowdown >= 0.8.0], [CXXFLAGS="$LOWDOWN_CFLAGS $CXXFLAGS"])
 
 # Setuid installations.
 AC_CHECK_FUNCS([setresuid setreuid lchown])
@@ -287,24 +273,14 @@ AC_CHECK_FUNCS([strsignal posix_fallocate sysconf])
 
 # This is needed if bzip2 is a static library, and the Nix libraries
 # are dynamic.
-if test "$(uname)" = "Darwin"; then
+case "${host_os}" in
+  darwin*)
     LDFLAGS="-all_load $LDFLAGS"
-fi
+    ;;
+esac
 
 
-# Do we have GNU tar?
-AC_MSG_CHECKING([if you have a recent GNU tar])
-if $tar --version 2> /dev/null | grep -q GNU && tar cvf /dev/null --warning=no-timestamp ./config.log > /dev/null; then
-    AC_MSG_RESULT(yes)
-    tarFlags="--warning=no-timestamp"
-else
-    AC_MSG_RESULT(no)
-fi
-AC_SUBST(tarFlags)
-
-
-AC_ARG_WITH(sandbox-shell, AC_HELP_STRING([--with-sandbox-shell=PATH],
-  [path of a statically-linked shell to use as /bin/sh in sandboxes]),
+AC_ARG_WITH(sandbox-shell, AS_HELP_STRING([--with-sandbox-shell=PATH],[path of a statically-linked shell to use as /bin/sh in sandboxes]),
   sandbox_shell=$withval)
 AC_SUBST(sandbox_shell)
 
@@ -319,6 +295,6 @@ done
 
 rm -f Makefile.config
 
-AC_CONFIG_HEADER([config.h])
+AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_FILES([])
 AC_OUTPUT

doc/manual/generate-builtins.nix

@@ -6,9 +6,11 @@ builtins:
 concatStrings (map
   (name:
     let builtin = builtins.${name}; in
-    "  - `builtins.${name}` " + concatStringsSep " " (map (s: "*${s}*") builtin.args)
-    + "  \n\n"
-    + concatStrings (map (s: "    ${s}\n") (splitLines builtin.doc)) + "\n\n"
+    "<dt><code>${name} "
+    + concatStringsSep " " (map (s: "<var>${s}</var>") builtin.args)
+    + "</code></dt>"
+    + "<dd>\n\n"
+    + builtin.doc
+    + "\n\n</dd>"
   )
   (attrNames builtins))
-

doc/manual/generate-manpage.nix

@@ -1,4 +1,4 @@
-command:
+{ command, renderLinks ? false }:
 
 with builtins;
 with import ./utils.nix;
@@ -7,7 +7,10 @@ let
 
   showCommand =
     { command, def, filename }:
-    "# Name\n\n"
+    ''
+      **Warning**: This program is **experimental** and its interface is subject to change.
+    ''
+    + "# Name\n\n"
     + "`${command}` - ${def.description}\n\n"
     + "# Synopsis\n\n"
     + showSynopsis { inherit command; args = def.args; }
@@ -17,7 +20,11 @@ let
            categories = sort (x: y: x.id < y.id) (unique (map (cmd: cmd.category) (attrValues def.commands)));
            listCommands = cmds:
              concatStrings (map (name:
-               "* [`${command} ${name}`](./${appendName filename name}.md) - ${cmds.${name}.description}\n")
+               "* "
+               + (if renderLinks
+                  then "[`${command} ${name}`](./${appendName filename name}.md)"
+                  else "`${command} ${name}`")
+               + " - ${cmds.${name}.description}\n")
                (attrNames cmds));
          in
          "where *subcommand* is one of the following:\n\n"
@@ -86,7 +93,7 @@ let
 in
 
 let
-  manpages = processCommand { filename = "nix"; command = "nix"; def = command; };
+  manpages = processCommand { filename = "nix"; command = "nix"; def = builtins.fromJSON command; };
   summary = concatStrings (map (manpage: "    - [${manpage.command}](command-ref/new-cli/${manpage.name})\n") manpages);
 in
 (listToAttrs manpages) // { "SUMMARY.md" = summary; }

doc/manual/local.mk

@@ -1,7 +1,5 @@
 ifeq ($(doc_generate),yes)
 
-MANUAL_SRCS := $(call rwildcard, $(d)/src, *.md)
-
 # Generate man pages.
 man-pages := $(foreach n, \
   nix-env.1 nix-build.1 nix-shell.1 nix-store.1 nix-instantiate.1 \
@@ -25,19 +23,19 @@ nix-eval = $(dummy-env) $(bindir)/nix eval --experimental-features nix-command -
 $(d)/%.1: $(d)/src/command-ref/%.md
 	@printf "Title: %s\n\n" "$$(basename $@ .1)" > $^.tmp
 	@cat $^ >> $^.tmp
-	$(trace-gen) lowdown -sT man $^.tmp -o $@
+	$(trace-gen) lowdown -sT man -M section=1 $^.tmp -o $@
 	@rm $^.tmp
 
 $(d)/%.8: $(d)/src/command-ref/%.md
 	@printf "Title: %s\n\n" "$$(basename $@ .8)" > $^.tmp
 	@cat $^ >> $^.tmp
-	$(trace-gen) lowdown -sT man $^.tmp -o $@
+	$(trace-gen) lowdown -sT man -M section=8 $^.tmp -o $@
 	@rm $^.tmp
 
 $(d)/nix.conf.5: $(d)/src/command-ref/conf-file.md
 	@printf "Title: %s\n\n" "$$(basename $@ .5)" > $^.tmp
 	@cat $^ >> $^.tmp
-	$(trace-gen) lowdown -sT man $^.tmp -o $@
+	$(trace-gen) lowdown -sT man -M section=5 $^.tmp -o $@
 	@rm $^.tmp
 
 $(d)/src/SUMMARY.md: $(d)/src/SUMMARY.md.in $(d)/src/command-ref/new-cli
@@ -46,7 +44,7 @@ $(d)/src/SUMMARY.md: $(d)/src/SUMMARY.md.in $(d)/src/command-ref/new-cli
 
 $(d)/src/command-ref/new-cli: $(d)/nix.json $(d)/generate-manpage.nix $(bindir)/nix
 	@rm -rf $@
-	$(trace-gen) $(nix-eval) --write-to $@ --expr 'import doc/manual/generate-manpage.nix (builtins.fromJSON (builtins.readFile $<))'
+	$(trace-gen) $(nix-eval) --write-to $@ --expr 'import doc/manual/generate-manpage.nix { command = builtins.readFile $<; renderLinks = true; }'
 
 $(d)/src/command-ref/conf-file.md: $(d)/conf-file.json $(d)/generate-options.nix $(d)/src/command-ref/conf-file-prefix.md $(bindir)/nix
 	@cat doc/manual/src/command-ref/conf-file-prefix.md > $@.tmp
@@ -64,6 +62,7 @@ $(d)/conf-file.json: $(bindir)/nix
 $(d)/src/expressions/builtins.md: $(d)/builtins.json $(d)/generate-builtins.nix $(d)/src/expressions/builtins-prefix.md $(bindir)/nix
 	@cat doc/manual/src/expressions/builtins-prefix.md > $@.tmp
 	$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-builtins.nix (builtins.fromJSON (builtins.readFile $<))' >> $@.tmp
+	@cat doc/manual/src/expressions/builtins-suffix.md >> $@.tmp
 	@mv $@.tmp $@
 
 $(d)/builtins.json: $(bindir)/nix
@@ -74,17 +73,28 @@ $(d)/builtins.json: $(bindir)/nix
 install: $(docdir)/manual/index.html
 
 # Generate 'nix' manpages.
-install: $(d)/src/command-ref/new-cli
+install: $(mandir)/man1/nix3-manpages
+man: doc/manual/generated/man1/nix3-manpages
+all: doc/manual/generated/man1/nix3-manpages
+
+$(mandir)/man1/nix3-manpages: doc/manual/generated/man1/nix3-manpages
+	@mkdir -p $(DESTDIR)$$(dirname $@)
+	$(trace-install) install -m 0644 $$(dirname $<)/* $(DESTDIR)$$(dirname $@)
+
+doc/manual/generated/man1/nix3-manpages: $(d)/src/command-ref/new-cli
+	@mkdir -p $(DESTDIR)$$(dirname $@)
 	$(trace-gen) for i in doc/manual/src/command-ref/new-cli/*.md; do \
 	  name=$$(basename $$i .md); \
+	  tmpFile=$$(mktemp); \
 	  if [[ $$name = SUMMARY ]]; then continue; fi; \
-	  printf "Title: %s\n\n" "$$name" > $$i.tmp; \
-	  cat $$i >> $$i.tmp; \
-	  lowdown -sT man $$i.tmp -o $(mandir)/man1/$$name.1; \
+	  printf "Title: %s\n\n" "$$name" > $$tmpFile; \
+	  cat $$i >> $$tmpFile; \
+	  lowdown -sT man -M section=1 $$tmpFile -o $(DESTDIR)$$(dirname $@)/$$name.1; \
+	  rm $$tmpFile; \
 	done
+	@touch $@
 
-$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/command-ref/new-cli $(d)/src/command-ref/conf-file.md $(d)/src/expressions/builtins.md
-	$(trace-gen) RUST_LOG=warn mdbook build doc/manual -d $(docdir)/manual
-	@cp doc/manual/highlight.pack.js $(docdir)/manual/highlight.js
+$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/command-ref/new-cli $(d)/src/command-ref/conf-file.md $(d)/src/expressions/builtins.md $(call rwildcard, $(d)/src, *.md)
+	$(trace-gen) RUST_LOG=warn mdbook build doc/manual -d $(DESTDIR)$(docdir)/manual
 
 endif

doc/manual/src/SUMMARY.md.in

@@ -70,6 +70,7 @@
   - [Hacking](contributing/hacking.md)
   - [CLI guideline](contributing/cli-guideline.md)
 - [Release Notes](release-notes/release-notes.md)
+  - [Release 2.4 (2021-11-01)](release-notes/rl-2.4.md)
   - [Release 2.3 (2019-09-04)](release-notes/rl-2.3.md)
   - [Release 2.2 (2019-01-11)](release-notes/rl-2.2.md)
   - [Release 2.1 (2018-09-02)](release-notes/rl-2.1.md)

doc/manual/src/advanced-topics/cores-vs-jobs.md

@@ -4,13 +4,13 @@ Nix has two relevant settings with regards to how your CPU cores will
 be utilized: `cores` and `max-jobs`. This chapter will talk about what
 they are, how they interact, and their configuration trade-offs.
 
-  - `max-jobs`  
+  - `max-jobs`\
     Dictates how many separate derivations will be built at the same
     time. If you set this to zero, the local machine will do no
     builds.  Nix will still substitute from binary caches, and build
     remotely if remote builders are configured.
 
-  - `cores`  
+  - `cores`\
     Suggests how many cores each derivation should use. Similar to
     `make -j`.
 

doc/manual/src/advanced-topics/distributed-builds.md

@@ -37,7 +37,7 @@ then you need to ensure that the `PATH` of non-interactive login shells
 contains Nix.
 
 > **Warning**
-> 
+>
 > If you are building via the Nix daemon, it is the Nix daemon user
 > account (that is, `root`) that should have SSH access to the remote
 > machine. If you can’t or don’t want to configure `root` to be able to
@@ -52,7 +52,7 @@ example, the following command allows you to build a derivation for
 ```console
 $ uname
 Linux
-    
+
 $ nix build \
   '(with import <nixpkgs> { system = "x86_64-darwin"; }; runCommand "foo" {} "uname > $out")' \
   --builders 'ssh://mac x86_64-darwin'
@@ -103,7 +103,7 @@ default, set it to `-`.
     ```nix
     requiredSystemFeatures = [ "kvm" ];
     ```
-    
+
     will cause the build to be performed on a machine that has the `kvm`
     feature.
 
@@ -112,6 +112,10 @@ default, set it to `-`.
     features appear in the derivation’s `requiredSystemFeatures`
     attribute..
 
+8.  The (base64-encoded) public host key of the remote machine. If omitted, SSH
+    will use its regular known-hosts file. Specifically, the field is calculated
+    via `base64 -w0 /etc/ssh/ssh_host_ed25519_key.pub`.
+
 For example, the machine specification
 
     nix@scratchy.labs.cs.uu.nl  i686-linux      /home/nix/.ssh/id_scratchy_auto        8 1 kvm

doc/manual/src/command-ref/env-common.md

@@ -2,45 +2,49 @@
 
 Most Nix commands interpret the following environment variables:
 
-  - `IN_NIX_SHELL`  
+  - `IN_NIX_SHELL`\
     Indicator that tells if the current environment was set up by
     `nix-shell`. Since Nix 2.0 the values are `"pure"` and `"impure"`
 
-  - `NIX_PATH`  
+  - `NIX_PATH`\
     A colon-separated list of directories used to look up Nix
     expressions enclosed in angle brackets (i.e., `<path>`). For
     instance, the value
-    
+
         /home/eelco/Dev:/etc/nixos
-    
+
     will cause Nix to look for paths relative to `/home/eelco/Dev` and
     `/etc/nixos`, in this order. It is also possible to match paths
     against a prefix. For example, the value
-    
+
         nixpkgs=/home/eelco/Dev/nixpkgs-branch:/etc/nixos
-    
+
     will cause Nix to search for `<nixpkgs/path>` in
     `/home/eelco/Dev/nixpkgs-branch/path` and `/etc/nixos/nixpkgs/path`.
-    
+
     If a path in the Nix search path starts with `http://` or
     `https://`, it is interpreted as the URL of a tarball that will be
     downloaded and unpacked to a temporary location. The tarball must
     consist of a single top-level directory. For example, setting
     `NIX_PATH` to
-    
-        nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-15.09.tar.gz
-    
-    tells Nix to download the latest revision in the Nixpkgs/NixOS 15.09
-    channel.
-    
-    A following shorthand can be used to refer to the official channels:
-    
-        nixpkgs=channel:nixos-15.09
-    
-    The search path can be extended using the `-I` option, which takes
-    precedence over `NIX_PATH`.
 
-  - `NIX_IGNORE_SYMLINK_STORE`  
+        nixpkgs=https://github.com/NixOS/nixpkgs/archive/master.tar.gz
+
+    tells Nix to download and use the current contents of the
+    `master` branch in the `nixpkgs` repository.
+
+    The URLs of the tarballs from the official nixos.org channels (see
+    [the manual for `nix-channel`](nix-channel.md)) can be abbreviated
+    as `channel:<channel-name>`.  For instance, the following two
+    values of `NIX_PATH` are equivalent:
+
+        nixpkgs=channel:nixos-21.05
+        nixpkgs=https://nixos.org/channels/nixos-21.05/nixexprs.tar.xz
+
+    The Nix search path can also be extended using the `-I` option to
+    many Nix commands, which takes precedence over `NIX_PATH`.
+
+  - `NIX_IGNORE_SYMLINK_STORE`\
     Normally, the Nix store directory (typically `/nix/store`) is not
     allowed to contain any symlink components. This is to prevent
     “impure” builds. Builders sometimes “canonicalise” paths by
@@ -50,7 +54,7 @@ Most Nix commands interpret the following environment variables:
     builds are deployed to machines where `/nix/store` resolves
     differently. If you are sure that you’re not going to do that, you
     can set `NIX_IGNORE_SYMLINK_STORE` to `1`.
-    
+
     Note that if you’re symlinking the Nix store so that you can put it
     on another file system than the root file system, on Linux you’re
     better off using `bind` mount points, e.g.,
@@ -59,44 +63,44 @@ Most Nix commands interpret the following environment variables:
     $ mkdir /nix
     $ mount -o bind /mnt/otherdisk/nix /nix
     ```
-    
+
     Consult the mount 8 manual page for details.
 
-  - `NIX_STORE_DIR`  
+  - `NIX_STORE_DIR`\
     Overrides the location of the Nix store (default `prefix/store`).
 
-  - `NIX_DATA_DIR`  
+  - `NIX_DATA_DIR`\
     Overrides the location of the Nix static data directory (default
     `prefix/share`).
 
-  - `NIX_LOG_DIR`  
+  - `NIX_LOG_DIR`\
     Overrides the location of the Nix log directory (default
     `prefix/var/log/nix`).
 
-  - `NIX_STATE_DIR`  
+  - `NIX_STATE_DIR`\
     Overrides the location of the Nix state directory (default
     `prefix/var/nix`).
 
-  - `NIX_CONF_DIR`  
+  - `NIX_CONF_DIR`\
     Overrides the location of the system Nix configuration directory
     (default `prefix/etc/nix`).
 
-  - `NIX_CONFIG`  
+  - `NIX_CONFIG`\
     Applies settings from Nix configuration from the environment.
     The content is treated as if it was read from a Nix configuration file.
     Settings are separated by the newline character.
 
-  - `NIX_USER_CONF_FILES`  
+  - `NIX_USER_CONF_FILES`\
     Overrides the location of the user Nix configuration files to load
     from (defaults to the XDG spec locations). The variable is treated
     as a list separated by the `:` token.
 
-  - `TMPDIR`  
+  - `TMPDIR`\
     Use the specified directory to store temporary files. In particular,
     this includes temporary build directories; these can take up
     substantial amounts of disk space. The default is `/tmp`.
 
-  - `NIX_REMOTE`  
+  - `NIX_REMOTE`\
     This variable should be set to `daemon` if you want to use the Nix
     daemon to execute Nix operations. This is necessary in [multi-user
     Nix installations](../installation/multi-user.md). If the Nix
@@ -104,16 +108,16 @@ Most Nix commands interpret the following environment variables:
     should be set to `unix://path/to/socket`. Otherwise, it should be
     left unset.
 
-  - `NIX_SHOW_STATS`  
+  - `NIX_SHOW_STATS`\
     If set to `1`, Nix will print some evaluation statistics, such as
     the number of values allocated.
 
-  - `NIX_COUNT_CALLS`  
+  - `NIX_COUNT_CALLS`\
     If set to `1`, Nix will print how often functions were called during
     Nix expression evaluation. This is useful for profiling your Nix
     expressions.
 
-  - `GC_INITIAL_HEAP_SIZE`  
+  - `GC_INITIAL_HEAP_SIZE`\
     If Nix has been configured to use the Boehm garbage collector, this
     variable sets the initial size of the heap in bytes. It defaults to
     384 MiB. Setting it to a low value reduces memory consumption, but

doc/manual/src/command-ref/nix-build.md

@@ -47,16 +47,16 @@ All options not listed here are passed to `nix-store
 --realise`, except for `--arg` and `--attr` / `-A` which are passed to
 `nix-instantiate`.
 
-  - `--no-out-link`  
+  - `--no-out-link`\
     Do not create a symlink to the output path. Note that as a result
     the output does not become a root of the garbage collector, and so
     might be deleted by `nix-store
                     --gc`.
 
-  - `--dry-run`  
+  - `--dry-run`\
     Show what store paths would be built or downloaded.
 
-  - `--out-link` / `-o` *outlink*  
+  - `--out-link` / `-o` *outlink*\
     Change the name of the symlink to the output path created from
     `result` to *outlink*.
 

doc/manual/src/command-ref/nix-channel.md

@@ -17,26 +17,26 @@ To see the list of official NixOS channels, visit
 
 This command has the following operations:
 
-  - `--add` *url* \[*name*\]  
+  - `--add` *url* \[*name*\]\
     Adds a channel named *name* with URL *url* to the list of subscribed
     channels. If *name* is omitted, it defaults to the last component of
     *url*, with the suffixes `-stable` or `-unstable` removed.
 
-  - `--remove` *name*  
+  - `--remove` *name*\
     Removes the channel named *name* from the list of subscribed
     channels.
 
-  - `--list`  
+  - `--list`\
     Prints the names and URLs of all subscribed channels on standard
     output.
 
-  - `--update` \[*names*…\]  
+  - `--update` \[*names*…\]\
     Downloads the Nix expressions of all subscribed channels (or only
     those included in *names* if specified) and makes them the default
     for `nix-env` operations (by symlinking them from the directory
     `~/.nix-defexpr`).
 
-  - `--rollback` \[*generation*\]  
+  - `--rollback` \[*generation*\]\
     Reverts the previous call to `nix-channel
                     --update`. Optionally, you can specify a specific channel generation
     number to restore.
@@ -70,14 +70,14 @@ $ nix-instantiate --eval -E '(import <nixpkgs> {}).lib.version'
 
 # Files
 
-  - `/nix/var/nix/profiles/per-user/username/channels`  
+  - `/nix/var/nix/profiles/per-user/username/channels`\
     `nix-channel` uses a `nix-env` profile to keep track of previous
     versions of the subscribed channels. Every time you run `nix-channel
     --update`, a new channel generation (that is, a symlink to the
     channel Nix expressions in the Nix store) is created. This enables
     `nix-channel --rollback` to revert to previous versions.
 
-  - `~/.nix-defexpr/channels`  
+  - `~/.nix-defexpr/channels`\
     This is a symlink to
     `/nix/var/nix/profiles/per-user/username/channels`. It ensures that
     `nix-env` can find your channels. In a multi-user installation, you
@@ -89,7 +89,7 @@ $ nix-instantiate --eval -E '(import <nixpkgs> {}).lib.version'
 A channel URL should point to a directory containing the following
 files:
 
-  - `nixexprs.tar.xz`  
+  - `nixexprs.tar.xz`\
     A tarball containing Nix expressions and files referenced by them
     (such as build scripts and patches). At the top level, the tarball
     should contain a single directory. That directory must contain a

doc/manual/src/command-ref/nix-copy-closure.md

@@ -35,21 +35,21 @@ and second to send the dump of those paths.  If this bothers you, use
 
 # Options
 
-  - `--to`  
+  - `--to`\
     Copy the closure of _paths_ from the local Nix store to the Nix
     store on _machine_. This is the default.
 
-  - `--from`  
+  - `--from`\
     Copy the closure of _paths_ from the Nix store on _machine_ to the
     local Nix store.
 
-  - `--gzip`  
+  - `--gzip`\
     Enable compression of the SSH connection.
 
-  - `--include-outputs`  
+  - `--include-outputs`\
     Also copy the outputs of store derivations included in the closure.
 
-  - `--use-substitutes` / `-s`  
+  - `--use-substitutes` / `-s`\
     Attempt to download missing paths on the target machine using Nix’s
     substitute mechanism.  Any paths that cannot be substituted on the
     target are still copied normally from the source.  This is useful,
@@ -58,12 +58,12 @@ and second to send the dump of those paths.  If this bothers you, use
     `nixos.org` (the default binary cache server) is
     fast.
 
-  - `-v`  
+  - `-v`\
     Show verbose output.
 
 # Environment variables
 
-  - `NIX_SSHOPTS`  
+  - `NIX_SSHOPTS`\
     Additional options to be passed to `ssh` on the command
     line.
 

doc/manual/src/command-ref/nix-env.md

@@ -36,27 +36,27 @@ case-sensitive. The regular expression can optionally be followed by a
 dash and a version number; if omitted, any version of the package will
 match. Here are some examples:
 
-  - `firefox`  
+  - `firefox`\
     Matches the package name `firefox` and any version.
 
-  - `firefox-32.0`  
+  - `firefox-32.0`\
     Matches the package name `firefox` and version `32.0`.
 
-  - `gtk\\+`  
+  - `gtk\\+`\
     Matches the package name `gtk+`. The `+` character must be escaped
     using a backslash to prevent it from being interpreted as a
     quantifier, and the backslash must be escaped in turn with another
     backslash to ensure that the shell passes it on.
 
-  - `.\*`  
+  - `.\*`\
     Matches any package name. This is the default for most commands.
 
-  - `'.*zip.*'`  
+  - `'.*zip.*'`\
     Matches any package name containing the string `zip`. Note the dots:
     `'*zip*'` does not work, because in a regular expression, the
     character `*` is interpreted as a quantifier.
 
-  - `'.*(firefox|chromium).*'`  
+  - `'.*(firefox|chromium).*'`\
     Matches any package name containing the strings `firefox` or
     `chromium`.
 
@@ -66,7 +66,7 @@ This section lists the options that are common to all operations. These
 options are allowed for every subcommand, though they may not always
 have an effect.
 
-  - `--file` / `-f` *path*  
+  - `--file` / `-f` *path*\
     Specifies the Nix expression (designated below as the *active Nix
     expression*) used by the `--install`, `--upgrade`, and `--query
     --available` operations to obtain derivations. The default is
@@ -77,13 +77,13 @@ have an effect.
     unpacked to a temporary location. The tarball must include a single
     top-level directory containing at least a file named `default.nix`.
 
-  - `--profile` / `-p` *path*  
+  - `--profile` / `-p` *path*\
     Specifies the profile to be used by those operations that operate on
     a profile (designated below as the *active profile*). A profile is a
     sequence of user environments called *generations*, one of which is
     the *current generation*.
 
-  - `--dry-run`  
+  - `--dry-run`\
     For the `--install`, `--upgrade`, `--uninstall`,
     `--switch-generation`, `--delete-generations` and `--rollback`
     operations, this flag will cause `nix-env` to print what *would* be
@@ -93,7 +93,7 @@ have an effect.
     [substituted](../glossary.md) (i.e., downloaded) and which paths
     will be built from source (because no substitute is available).
 
-  - `--system-filter` *system*  
+  - `--system-filter` *system*\
     By default, operations such as `--query
                     --available` show derivations matching any platform. This option
     allows you to use derivations for the specified platform *system*.
@@ -102,7 +102,7 @@ have an effect.
 
 # Files
 
-  - `~/.nix-defexpr`  
+  - `~/.nix-defexpr`\
     The source for the default Nix expressions used by the
     `--install`, `--upgrade`, and `--query --available` operations to
     obtain derivations. The `--file` option may be used to override
@@ -140,7 +140,7 @@ have an effect.
     The command `nix-channel` places symlinks to the downloaded Nix
     expressions from each subscribed channel in this directory.
 
-  - `~/.nix-profile`  
+  - `~/.nix-profile`\
     A symbolic link to the user's current profile. By default, this
     symlink points to `prefix/var/nix/profiles/default`. The `PATH`
     environment variable should include `~/.nix-profile/bin` for the
@@ -217,13 +217,13 @@ a number of possible ways:
 
 ## Flags
 
-  - `--prebuilt-only` / `-b`  
+  - `--prebuilt-only` / `-b`\
     Use only derivations for which a substitute is registered, i.e.,
     there is a pre-built binary available that can be downloaded in lieu
     of building the derivation. Thus, no packages will be built from
     source.
 
-  - `--preserve-installed`; `-P`  
+  - `--preserve-installed`; `-P`\
     Do not remove derivations with a name matching one of the
     derivations being installed. Usually, trying to have two versions of
     the same package installed in the same generation of a profile will
@@ -231,7 +231,7 @@ a number of possible ways:
     clashes between the two versions. However, this is not the case for
     all packages.
 
-  - `--remove-all`; `-r`  
+  - `--remove-all`; `-r`\
     Remove all previously installed packages first. This is equivalent
     to running `nix-env -e '.*'` first, except that everything happens
     in a single transaction.
@@ -346,24 +346,24 @@ version is installed.
 
 ## Flags
 
-  - `--lt`  
+  - `--lt`\
     Only upgrade a derivation to newer versions. This is the default.
 
-  - `--leq`  
+  - `--leq`\
     In addition to upgrading to newer versions, also “upgrade” to
     derivations that have the same version. Version are not a unique
     identification of a derivation, so there may be many derivations
     that have the same version. This flag may be useful to force
     “synchronisation” between the installed and available derivations.
 
-  - `--eq`  
+  - `--eq`\
     *Only* “upgrade” to derivations that have the same version. This may
     not seem very useful, but it actually is, e.g., when there is a new
     release of Nixpkgs and you want to replace installed applications
     with the same versions built against newer dependencies (to reduce
     the number of dependencies floating around on your system).
 
-  - `--always`  
+  - `--always`\
     In addition to upgrading to newer versions, also “upgrade” to
     derivations that have the same or a lower version. I.e., derivations
     may actually be downgraded depending on what is available in the
@@ -578,11 +578,11 @@ The derivations are sorted by their `name` attributes.
 The following flags specify the set of things on which the query
 operates.
 
-  - `--installed`  
+  - `--installed`\
     The query operates on the store paths that are installed in the
     current generation of the active profile. This is the default.
 
-  - `--available`; `-a`  
+  - `--available`; `-a`\
     The query operates on the derivations that are available in the
     active Nix expression.
 
@@ -593,24 +593,24 @@ selected derivations. Multiple flags may be specified, in which case the
 information is shown in the order given here. Note that the name of the
 derivation is shown unless `--no-name` is specified.
 
-  - `--xml`  
+  - `--xml`\
     Print the result in an XML representation suitable for automatic
     processing by other tools. The root element is called `items`, which
     contains a `item` element for each available or installed
     derivation. The fields discussed below are all stored in attributes
     of the `item` elements.
 
-  - `--json`  
+  - `--json`\
     Print the result in a JSON representation suitable for automatic
     processing by other tools.
 
-  - `--prebuilt-only` / `-b`  
+  - `--prebuilt-only` / `-b`\
     Show only derivations for which a substitute is registered, i.e.,
     there is a pre-built binary available that can be downloaded in lieu
     of building the derivation. Thus, this shows all packages that
     probably can be installed quickly.
 
-  - `--status`; `-s`  
+  - `--status`; `-s`\
     Print the *status* of the derivation. The status consists of three
     characters. The first is `I` or `-`, indicating whether the
     derivation is currently installed in the current generation of the
@@ -621,49 +621,49 @@ derivation is shown unless `--no-name` is specified.
     derivation to be built. The third is `S` or `-`, indicating whether
     a substitute is available for the derivation.
 
-  - `--attr-path`; `-P`  
+  - `--attr-path`; `-P`\
     Print the *attribute path* of the derivation, which can be used to
     unambiguously select it using the `--attr` option available in
     commands that install derivations like `nix-env --install`. This
     option only works together with `--available`
 
-  - `--no-name`  
+  - `--no-name`\
     Suppress printing of the `name` attribute of each derivation.
 
-  - `--compare-versions` / `-c`  
+  - `--compare-versions` / `-c`\
     Compare installed versions to available versions, or vice versa (if
     `--available` is given). This is useful for quickly seeing whether
     upgrades for installed packages are available in a Nix expression. A
     column is added with the following meaning:
 
-      - `<` *version*  
+      - `<` *version*\
         A newer version of the package is available or installed.
 
-      - `=` *version*  
+      - `=` *version*\
         At most the same version of the package is available or
         installed.
 
-      - `>` *version*  
+      - `>` *version*\
         Only older versions of the package are available or installed.
 
-      - `- ?`  
+      - `- ?`\
         No version of the package is available or installed.
 
-  - `--system`  
+  - `--system`\
     Print the `system` attribute of the derivation.
 
-  - `--drv-path`  
+  - `--drv-path`\
     Print the path of the store derivation.
 
-  - `--out-path`  
+  - `--out-path`\
     Print the output path of the derivation.
 
-  - `--description`  
+  - `--description`\
     Print a short (one-line) description of the derivation, if
     available. The description is taken from the `meta.description`
     attribute of the derivation.
 
-  - `--meta`  
+  - `--meta`\
     Print all of the meta-attributes of the derivation. This option is
     only available with `--xml` or `--json`.
 
@@ -874,7 +874,7 @@ error: no generation older than the current (91) exists
 
 # Environment variables
 
-  - `NIX_PROFILE`  
+  - `NIX_PROFILE`\
     Location of the Nix profile. Defaults to the target of the symlink
     `~/.nix-profile`, if it exists, or `/nix/var/nix/profiles/default`
     otherwise.

doc/manual/src/command-ref/nix-hash.md

@@ -29,29 +29,29 @@ md5sum`.
 
 # Options
 
-  - `--flat`  
+  - `--flat`\
     Print the cryptographic hash of the contents of each regular file
     *path*. That is, do not compute the hash over the dump of *path*.
     The result is identical to that produced by the GNU commands
     `md5sum` and `sha1sum`.
 
-  - `--base32`  
+  - `--base32`\
     Print the hash in a base-32 representation rather than hexadecimal.
     This base-32 representation is more compact and can be used in Nix
     expressions (such as in calls to `fetchurl`).
 
-  - `--truncate`  
+  - `--truncate`\
     Truncate hashes longer than 160 bits (such as SHA-256) to 160 bits.
 
-  - `--type` *hashAlgo*  
+  - `--type` *hashAlgo*\
     Use the specified cryptographic hash algorithm, which can be one of
     `md5`, `sha1`, `sha256`, and `sha512`.
 
-  - `--to-base16`  
+  - `--to-base16`\
     Don’t hash anything, but convert the base-32 hash representation
     *hash* to hexadecimal.
 
-  - `--to-base32`  
+  - `--to-base32`\
     Don’t hash anything, but convert the hexadecimal hash representation
     *hash* to base-32.
 

doc/manual/src/command-ref/nix-instantiate.md

@@ -29,26 +29,26 @@ standard input.
 
 # Options
 
-  - `--add-root` *path*  
+  - `--add-root` *path*\
     See the [corresponding option](nix-store.md) in `nix-store`.
 
-  - `--parse`  
+  - `--parse`\
     Just parse the input files, and print their abstract syntax trees on
     standard output in ATerm format.
 
-  - `--eval`  
+  - `--eval`\
     Just parse and evaluate the input files, and print the resulting
     values on standard output. No instantiation of store derivations
     takes place.
 
-  - `--find-file`  
+  - `--find-file`\
     Look up the given files in Nix’s search path (as specified by the
     `NIX_PATH` environment variable). If found, print the corresponding
     absolute paths on standard output. For instance, if `NIX_PATH` is
     `nixpkgs=/home/alice/nixpkgs`, then `nix-instantiate --find-file
     nixpkgs/default.nix` will print `/home/alice/nixpkgs/default.nix`.
 
-  - `--strict`  
+  - `--strict`\
     When used with `--eval`, recursively evaluate list elements and
     attributes. Normally, such sub-expressions are left unevaluated
     (since the Nix expression language is lazy).
@@ -58,17 +58,17 @@ standard input.
     > This option can cause non-termination, because lazy data
     > structures can be infinitely large.
 
-  - `--json`  
+  - `--json`\
     When used with `--eval`, print the resulting value as an JSON
     representation of the abstract syntax tree rather than as an ATerm.
 
-  - `--xml`  
+  - `--xml`\
     When used with `--eval`, print the resulting value as an XML
     representation of the abstract syntax tree rather than as an ATerm.
     The schema is the same as that used by the [`toXML`
     built-in](../expressions/builtins.md).
 
-  - `--read-write-mode`  
+  - `--read-write-mode`\
     When used with `--eval`, perform evaluation in read/write mode so
     nix language features that require it will still work (at the cost
     of needing to do instantiation of every evaluated derivation). If

doc/manual/src/command-ref/nix-prefetch-url.md

@@ -37,22 +37,22 @@ Nix store is also printed.
 
 # Options
 
-  - `--type` *hashAlgo*  
+  - `--type` *hashAlgo*\
     Use the specified cryptographic hash algorithm, which can be one of
     `md5`, `sha1`, `sha256`, and `sha512`.
 
-  - `--print-path`  
+  - `--print-path`\
     Print the store path of the downloaded file on standard output.
 
-  - `--unpack`  
+  - `--unpack`\
     Unpack the archive (which must be a tarball or zip file) and add the
     result to the Nix store. The resulting hash can be used with
     functions such as Nixpkgs’s `fetchzip` or `fetchFromGitHub`.
 
-  - `--executable`  
+  - `--executable`\
     Set the executable bit on the downloaded file.
 
-  - `--name` *name*  
+  - `--name` *name*\
     Override the name of the file in the Nix store. By default, this is
     `hash-basename`, where *basename* is the last component of *url*.
     Overriding the name is necessary when *basename* contains characters

doc/manual/src/command-ref/nix-shell.md

@@ -54,7 +54,7 @@ All options not listed here are passed to `nix-store
 --realise`, except for `--arg` and `--attr` / `-A` which are passed to
 `nix-instantiate`.
 
-  - `--command` *cmd*  
+  - `--command` *cmd*\
     In the environment of the derivation, run the shell command *cmd*.
     This command is executed in an interactive shell. (Use `--run` to
     use a non-interactive shell instead.) However, a call to `exit` is
@@ -64,36 +64,34 @@ All options not listed here are passed to `nix-store
     drop you into the interactive shell. This can be useful for doing
     any additional initialisation.
 
-  - `--run` *cmd*  
+  - `--run` *cmd*\
     Like `--command`, but executes the command in a non-interactive
     shell. This means (among other things) that if you hit Ctrl-C while
     the command is running, the shell exits.
 
-  - `--exclude` *regexp*  
+  - `--exclude` *regexp*\
     Do not build any dependencies whose store path matches the regular
     expression *regexp*. This option may be specified multiple times.
 
-  - `--pure`  
+  - `--pure`\
     If this flag is specified, the environment is almost entirely
     cleared before the interactive shell is started, so you get an
     environment that more closely corresponds to the “real” Nix build. A
     few variables, in particular `HOME`, `USER` and `DISPLAY`, are
-    retained. Note that (depending on your Bash
-    installation) `/etc/bashrc` is still sourced, so any variables set
-    there will affect the interactive shell.
+    retained.
 
-  - `--packages` / `-p` *packages*…  
+  - `--packages` / `-p` *packages*…\
     Set up an environment in which the specified packages are present.
     The command line arguments are interpreted as attribute names inside
     the Nix Packages collection. Thus, `nix-shell -p libjpeg openjdk`
     will start a shell in which the packages denoted by the attribute
     names `libjpeg` and `openjdk` are present.
 
-  - `-i` *interpreter*  
+  - `-i` *interpreter*\
     The chained script interpreter to be invoked by `nix-shell`. Only
     applicable in `#!`-scripts (described below).
 
-  - `--keep` *name*  
+  - `--keep` *name*\
     When a `--pure` shell is started, keep the listed environment
     variables.
 
@@ -101,7 +99,7 @@ The following common options are supported:
 
 # Environment variables
 
-  - `NIX_BUILD_SHELL`  
+  - `NIX_BUILD_SHELL`\
     Shell used to start the interactive environment. Defaults to the
     `bash` found in `PATH`.
 
@@ -232,22 +230,23 @@ terraform apply
 > in a nix-shell shebang.
 
 Finally, using the merging of multiple nix-shell shebangs the following
-Haskell script uses a specific branch of Nixpkgs/NixOS (the 18.03 stable
+Haskell script uses a specific branch of Nixpkgs/NixOS (the 20.03 stable
 branch):
 
 ```haskell
 #! /usr/bin/env nix-shell
-#! nix-shell -i runghc -p "haskellPackages.ghcWithPackages (ps: [ps.HTTP ps.tagsoup])"
-#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-18.03.tar.gz
+#! nix-shell -i runghc -p "haskellPackages.ghcWithPackages (ps: [ps.download-curl ps.tagsoup])"
+#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/nixos-20.03.tar.gz
 
-import Network.HTTP
+import Network.Curl.Download
 import Text.HTML.TagSoup
+import Data.Either
+import Data.ByteString.Char8 (unpack)
 
 -- Fetch nixos.org and print all hrefs.
 main = do
-  resp <- Network.HTTP.simpleHTTP (getRequest "http://nixos.org/")
-  body <- getResponseBody resp
-  let tags = filter (isTagOpenName "a") $ parseTags body
+  resp <- openURI "https://nixos.org/"
+  let tags = filter (isTagOpenName "a") $ parseTags $ unpack $ fromRight undefined resp
   let tags' = map (fromAttrib "href") tags
   mapM_ putStrLn $ filter (/= "") tags'
 ```

doc/manual/src/command-ref/nix-store.md

@@ -22,7 +22,7 @@ This section lists the options that are common to all operations. These
 options are allowed for every subcommand, though they may not always
 have an effect.
 
-  - `--add-root` *path*  
+  - `--add-root` *path*\
     Causes the result of a realisation (`--realise` and
     `--force-realise`) to be registered as a root of the garbage
     collector. *path* will be created as a symlink to the resulting
@@ -79,22 +79,22 @@ paths. Realisation is a somewhat overloaded term:
     system). If the path is already valid, we are done immediately.
     Otherwise, the path and any missing paths in its closure may be
     produced through substitutes. If there are no (successful)
-    subsitutes, realisation fails.
+    substitutes, realisation fails.
 
 The output path of each derivation is printed on standard output. (For
 non-derivations argument, the argument itself is printed.)
 
 The following flags are available:
 
-  - `--dry-run`  
+  - `--dry-run`\
     Print on standard error a description of what packages would be
     built or downloaded, without actually performing the operation.
 
-  - `--ignore-unknown`  
+  - `--ignore-unknown`\
     If a non-derivation path does not have a substitute, then silently
     ignore it.
 
-  - `--check`  
+  - `--check`\
     This option allows you to check whether a derivation is
     deterministic. It rebuilds the specified derivation and checks
     whether the result is bitwise-identical with the existing outputs,
@@ -110,20 +110,20 @@ The following flags are available:
 
 Special exit codes:
 
-  - `100`  
+  - `100`\
     Generic build failure, the builder process returned with a non-zero
     exit code.
 
-  - `101`  
+  - `101`\
     Build timeout, the build was aborted because it did not complete
     within the specified `timeout`.
 
-  - `102`  
+  - `102`\
     Hash mismatch, the build output was rejected because it does not
     match the [`outputHash` attribute of the
     derivation](../expressions/advanced-attributes.md).
 
-  - `104`  
+  - `104`\
     Not deterministic, the build succeeded in check mode but the
     resulting output is not binary reproducable.
 
@@ -170,7 +170,7 @@ access to a restricted ssh user.
 
 The following flags are available:
 
-  - `--write`  
+  - `--write`\
     Allow the connected client to request the realization of
     derivations. In effect, this can be used to make the host act as a
     remote builder.
@@ -200,18 +200,18 @@ reachable via file system references from a set of “roots”, are deleted.
 
 The following suboperations may be specified:
 
-  - `--print-roots`  
+  - `--print-roots`\
     This operation prints on standard output the set of roots used by
     the garbage collector.
 
-  - `--print-live`  
+  - `--print-live`\
     This operation prints on standard output the set of “live” store
     paths, which are all the store paths reachable from the roots. Live
     paths should never be deleted, since that would break consistency —
     it would become possible that applications are installed that
     reference things that are no longer present in the store.
 
-  - `--print-dead`  
+  - `--print-dead`\
     This operation prints out on standard output the set of “dead” store
     paths, which is just the opposite of the set of live paths: any path
     in the store that is not live (with respect to the roots) is dead.
@@ -219,7 +219,7 @@ The following suboperations may be specified:
 By default, all unreachable paths are deleted. The following options
 control what gets deleted and in what order:
 
-  - `--max-freed` *bytes*  
+  - `--max-freed` *bytes*\
     Keep deleting paths until at least *bytes* bytes have been deleted,
     then stop. The argument *bytes* can be followed by the
     multiplicative suffix `K`, `M`, `G` or `T`, denoting KiB, MiB, GiB
@@ -300,22 +300,22 @@ symlink.
 
 ## Common query options
 
-  - `--use-output`; `-u`  
+  - `--use-output`; `-u`\
     For each argument to the query that is a store derivation, apply the
     query to the output path of the derivation instead.
 
-  - `--force-realise`; `-f`  
+  - `--force-realise`; `-f`\
     Realise each argument to the query first (see [`nix-store
     --realise`](#operation---realise)).
 
 ## Queries
 
-  - `--outputs`  
+  - `--outputs`\
     Prints out the [output paths](../glossary.md) of the store
     derivations *paths*. These are the paths that will be produced when
     the derivation is built.
 
-  - `--requisites`; `-R`  
+  - `--requisites`; `-R`\
     Prints out the [closure](../glossary.md) of the store path *paths*.
 
     This query has one option:
@@ -332,31 +332,31 @@ symlink.
     dependencies) is obtained by distributing the closure of a store
     derivation and specifying the option `--include-outputs`.
 
-  - `--references`  
+  - `--references`\
     Prints the set of [references](../glossary.md) of the store paths
     *paths*, that is, their immediate dependencies. (For *all*
     dependencies, use `--requisites`.)
 
-  - `--referrers`  
+  - `--referrers`\
     Prints the set of *referrers* of the store paths *paths*, that is,
     the store paths currently existing in the Nix store that refer to
     one of *paths*. Note that contrary to the references, the set of
     referrers is not constant; it can change as store paths are added or
     removed.
 
-  - `--referrers-closure`  
+  - `--referrers-closure`\
     Prints the closure of the set of store paths *paths* under the
     referrers relation; that is, all store paths that directly or
     indirectly refer to one of *paths*. These are all the path currently
     in the Nix store that are dependent on *paths*.
 
-  - `--deriver`; `-d`  
+  - `--deriver`; `-d`\
     Prints the [deriver](../glossary.md) of the store paths *paths*. If
     the path has no deriver (e.g., if it is a source file), or if the
     deriver is not known (e.g., in the case of a binary-only
     deployment), the string `unknown-deriver` is printed.
 
-  - `--graph`  
+  - `--graph`\
     Prints the references graph of the store paths *paths* in the format
     of the `dot` tool of AT\&T's [Graphviz
     package](http://www.graphviz.org/). This can be used to visualise
@@ -364,39 +364,39 @@ symlink.
     this to a store derivation. To obtain a runtime dependency graph,
     apply it to an output path.
 
-  - `--tree`  
+  - `--tree`\
     Prints the references graph of the store paths *paths* as a nested
     ASCII tree. References are ordered by descending closure size; this
     tends to flatten the tree, making it more readable. The query only
     recurses into a store path when it is first encountered; this
     prevents a blowup of the tree representation of the graph.
 
-  - `--graphml`  
+  - `--graphml`\
     Prints the references graph of the store paths *paths* in the
     [GraphML](http://graphml.graphdrawing.org/) file format. This can be
     used to visualise dependency graphs. To obtain a build-time
     dependency graph, apply this to a store derivation. To obtain a
     runtime dependency graph, apply it to an output path.
 
-  - `--binding` *name*; `-b` *name*  
+  - `--binding` *name*; `-b` *name*\
     Prints the value of the attribute *name* (i.e., environment
     variable) of the store derivations *paths*. It is an error for a
     derivation to not have the specified attribute.
 
-  - `--hash`  
+  - `--hash`\
     Prints the SHA-256 hash of the contents of the store paths *paths*
     (that is, the hash of the output of `nix-store --dump` on the given
     paths). Since the hash is stored in the Nix database, this is a fast
     operation.
 
-  - `--size`  
+  - `--size`\
     Prints the size in bytes of the contents of the store paths *paths*
     — to be precise, the size of the output of `nix-store --dump` on
     the given paths. Note that the actual disk space required by the
     store paths may be higher, especially on filesystems with large
     cluster sizes.
 
-  - `--roots`  
+  - `--roots`\
     Prints the garbage collector roots that point, directly or
     indirectly, at the store paths *paths*.
 
@@ -513,7 +513,7 @@ public url or broke since the download expression was written.
 
 This operation has the following options:
 
-  - `--recursive`  
+  - `--recursive`\
     Use recursive instead of flat hashing mode, used when adding
     directories to the store.
 
@@ -540,14 +540,14 @@ being modified by non-Nix tools, or of bugs in Nix itself.
 
 This operation has the following options:
 
-  - `--check-contents`  
+  - `--check-contents`\
     Checks that the contents of every valid store path has not been
     altered by computing a SHA-256 hash of the contents and comparing it
     with the hash stored in the Nix database at build time. Paths that
     have been modified are printed out. For large stores,
     `--check-contents` is obviously quite slow.
 
-  - `--repair`  
+  - `--repair`\
     If any valid path is missing from the store, or (if
     `--check-contents` is given) the contents of a valid path has been
     modified, then try to repair the path by redownloading it. See

doc/manual/src/command-ref/opt-common.md

@@ -2,56 +2,56 @@
 
 Most Nix commands accept the following command-line options:
 
-  - `--help`  
+  - `--help`\
     Prints out a summary of the command syntax and exits.
 
-  - `--version`  
+  - `--version`\
     Prints out the Nix version number on standard output and exits.
 
-  - `--verbose` / `-v`  
+  - `--verbose` / `-v`\
     Increases the level of verbosity of diagnostic messages printed on
     standard error. For each Nix operation, the information printed on
     standard output is well-defined; any diagnostic information is
     printed on standard error, never on standard output.
-    
+
     This option may be specified repeatedly. Currently, the following
     verbosity levels exist:
-    
-      - 0  
+
+      - 0\
         “Errors only”: only print messages explaining why the Nix
         invocation failed.
-    
-      - 1  
+
+      - 1\
         “Informational”: print *useful* messages about what Nix is
         doing. This is the default.
-    
-      - 2  
+
+      - 2\
         “Talkative”: print more informational messages.
-    
-      - 3  
+
+      - 3\
         “Chatty”: print even more informational messages.
-    
-      - 4  
+
+      - 4\
         “Debug”: print debug information.
-    
-      - 5  
+
+      - 5\
         “Vomit”: print vast amounts of debug information.
 
-  - `--quiet`  
+  - `--quiet`\
     Decreases the level of verbosity of diagnostic messages printed on
     standard error. This is the inverse option to `-v` / `--verbose`.
-    
+
     This option may be specified repeatedly. See the previous verbosity
     levels list.
 
-  - `--log-format` *format*  
+  - `--log-format` *format*\
     This option can be used to change the output of the log format, with
     *format* being one of:
-    
-      - raw  
+
+      - raw\
         This is the raw format, as outputted by nix-build.
-    
-      - internal-json  
+
+      - internal-json\
         Outputs the logs in a structured manner.
 
         > **Warning**
@@ -60,30 +60,30 @@ Most Nix commands accept the following command-line options:
         > the error-messages (namely of the `msg`-field) can change
         > between releases.
 
-      - bar  
+      - bar\
         Only display a progress bar during the builds.
-    
-      - bar-with-logs  
+
+      - bar-with-logs\
         Display the raw logs, with the progress bar at the bottom.
 
-  - `--no-build-output` / `-Q`  
+  - `--no-build-output` / `-Q`\
     By default, output written by builders to standard output and
     standard error is echoed to the Nix command's standard error. This
     option suppresses this behaviour. Note that the builder's standard
     output and error are always written to a log file in
     `prefix/nix/var/log/nix`.
 
-  - `--max-jobs` / `-j` *number*  
+  - `--max-jobs` / `-j` *number*\
     Sets the maximum number of build jobs that Nix will perform in
     parallel to the specified number. Specify `auto` to use the number
     of CPUs in the system. The default is specified by the `max-jobs`
     configuration setting, which itself defaults to `1`. A higher
     value is useful on SMP systems or to exploit I/O latency.
-    
+
     Setting it to `0` disallows building on the local machine, which is
     useful when you want builds to happen only on remote builders.
 
-  - `--cores`  
+  - `--cores`\
     Sets the value of the `NIX_BUILD_CORES` environment variable in
     the invocation of builders. Builders can use this variable at
     their discretion to control the maximum amount of parallelism. For
@@ -94,18 +94,18 @@ Most Nix commands accept the following command-line options:
     means that the builder should use all available CPU cores in the
     system.
 
-  - `--max-silent-time`  
+  - `--max-silent-time`\
     Sets the maximum number of seconds that a builder can go without
     producing any data on standard output or standard error. The
     default is specified by the `max-silent-time` configuration
     setting. `0` means no time-out.
 
-  - `--timeout`  
+  - `--timeout`\
     Sets the maximum number of seconds that a builder can run. The
     default is specified by the `timeout` configuration setting. `0`
     means no timeout.
 
-  - `--keep-going` / `-k`  
+  - `--keep-going` / `-k`\
     Keep going in case of failed builds, to the greatest extent
     possible. That is, if building an input of some derivation fails,
     Nix will still build the other inputs, but not the derivation
@@ -113,17 +113,17 @@ Most Nix commands accept the following command-line options:
     for builds of substitutes), possibly killing builds in progress (in
     case of parallel or distributed builds).
 
-  - `--keep-failed` / `-K`  
+  - `--keep-failed` / `-K`\
     Specifies that in case of a build failure, the temporary directory
     (usually in `/tmp`) in which the build takes place should not be
     deleted. The path of the build directory is printed as an
     informational message.
 
-  - `--fallback`  
+  - `--fallback`\
     Whenever Nix attempts to build a derivation for which substitutes
     are known for each output path, but realising the output paths
     through the substitutes fails, fall back on building the derivation.
-    
+
     The most common scenario in which this is useful is when we have
     registered substitutes in order to perform binary distribution from,
     say, a network repository. If the repository is down, the
@@ -134,21 +134,12 @@ Most Nix commands accept the following command-line options:
     failure in obtaining the substitutes to lead to a full build from
     source (with the related consumption of resources).
 
-  - `--no-build-hook`  
-    Disables the build hook mechanism. This allows to ignore remote
-    builders if they are setup on the machine.
-    
-    It's useful in cases where the bandwidth between the client and the
-    remote builder is too low. In that case it can take more time to
-    upload the sources to the remote builder and fetch back the result
-    than to do the computation locally.
-
-  - `--readonly-mode`  
+  - `--readonly-mode`\
     When this option is used, no attempt is made to open the Nix
     database. Most Nix operations do need database access, so those
     operations will fail.
 
-  - `--arg` *name* *value*  
+  - `--arg` *name* *value*\
     This option is accepted by `nix-env`, `nix-instantiate`,
     `nix-shell` and `nix-build`. When evaluating Nix expressions, the
     expression evaluator will automatically try to call functions that
@@ -160,7 +151,7 @@ Most Nix commands accept the following command-line options:
     override a default value). That is, if the evaluator encounters a
     function with an argument named *name*, it will call it with value
     *value*.
-    
+
     For instance, the top-level `default.nix` in Nixpkgs is actually a
     function:
 
@@ -170,7 +161,7 @@ Most Nix commands accept the following command-line options:
       ...
     }: ...
     ```
-    
+
     So if you call this Nix expression (e.g., when you do `nix-env -i
     pkgname`), the function will be called automatically using the
     value [`builtins.currentSystem`](../expressions/builtins.md) for
@@ -179,13 +170,13 @@ Most Nix commands accept the following command-line options:
     since the argument is a Nix string literal, you have to escape the
     quotes.)
 
-  - `--argstr` *name* *value*  
+  - `--argstr` *name* *value*\
     This option is like `--arg`, only the value is not a Nix
     expression but a string. So instead of `--arg system
     \"i686-linux\"` (the outer quotes are to keep the shell happy) you
     can say `--argstr system i686-linux`.
 
-  - `--attr` / `-A` *attrPath*  
+  - `--attr` / `-A` *attrPath*\
     Select an attribute from the top-level Nix expression being
     evaluated. (`nix-env`, `nix-instantiate`, `nix-build` and
     `nix-shell` only.) The *attribute path* *attrPath* is a sequence
@@ -194,34 +185,34 @@ Most Nix commands accept the following command-line options:
     would cause the expression `e.xorg.xorgserver` to be used. See
     [`nix-env --install`](nix-env.md#operation---install) for some
     concrete examples.
-    
+
     In addition to attribute names, you can also specify array indices.
     For instance, the attribute path `foo.3.bar` selects the `bar`
     attribute of the fourth element of the array in the `foo` attribute
     of the top-level expression.
 
-  - `--expr` / `-E`  
+  - `--expr` / `-E`\
     Interpret the command line arguments as a list of Nix expressions to
     be parsed and evaluated, rather than as a list of file names of Nix
     expressions. (`nix-instantiate`, `nix-build` and `nix-shell` only.)
-    
+
     For `nix-shell`, this option is commonly used to give you a shell in
     which you can build the packages returned by the expression. If you
     want to get a shell which contain the *built* packages ready for
     use, give your expression to the `nix-shell -p` convenience flag
     instead.
 
-  - `-I` *path*  
+  - `-I` *path*\
     Add a path to the Nix expression search path. This option may be
     given multiple times. See the `NIX_PATH` environment variable for
     information on the semantics of the Nix search path. Paths added
     through `-I` take precedence over `NIX_PATH`.
 
-  - `--option` *name* *value*  
+  - `--option` *name* *value*\
     Set the Nix configuration option *name* to *value*. This overrides
     settings in the Nix configuration file (see nix.conf5).
 
-  - `--repair`  
+  - `--repair`\
     Fix corrupted or missing store paths by redownloading or rebuilding
     them. Note that this is slow because it requires computing a
     cryptographic hash of the contents of every path in the closure of

doc/manual/src/expressions/advanced-attributes.md

@@ -2,14 +2,14 @@
 
 Derivations can declare some infrequently used optional attributes.
 
-  - `allowedReferences`  
+  - `allowedReferences`\
     The optional attribute `allowedReferences` specifies a list of legal
     references (dependencies) of the output of the builder. For example,
-    
+
     ```nix
     allowedReferences = [];
     ```
-    
+
     enforces that the output of a derivation cannot have any runtime
     dependencies on its inputs. To allow an output to have a runtime
     dependency on itself, use `"out"` as a list item. This is used in
@@ -17,45 +17,45 @@ Derivations can declare some infrequently used optional attributes.
     booting Linux don’t have accidental dependencies on other paths in
     the Nix store.
 
-  - `allowedRequisites`  
+  - `allowedRequisites`\
     This attribute is similar to `allowedReferences`, but it specifies
     the legal requisites of the whole closure, so all the dependencies
     recursively. For example,
-    
+
     ```nix
     allowedRequisites = [ foobar ];
     ```
-    
+
     enforces that the output of a derivation cannot have any other
     runtime dependency than `foobar`, and in addition it enforces that
     `foobar` itself doesn't introduce any other dependency itself.
 
-  - `disallowedReferences`  
+  - `disallowedReferences`\
     The optional attribute `disallowedReferences` specifies a list of
     illegal references (dependencies) of the output of the builder. For
     example,
-    
+
     ```nix
     disallowedReferences = [ foo ];
     ```
-    
+
     enforces that the output of a derivation cannot have a direct
     runtime dependencies on the derivation `foo`.
 
-  - `disallowedRequisites`  
+  - `disallowedRequisites`\
     This attribute is similar to `disallowedReferences`, but it
     specifies illegal requisites for the whole closure, so all the
     dependencies recursively. For example,
-    
+
     ```nix
     disallowedRequisites = [ foobar ];
     ```
-    
+
     enforces that the output of a derivation cannot have any runtime
     dependency on `foobar` or any other derivation depending recursively
     on `foobar`.
 
-  - `exportReferencesGraph`  
+  - `exportReferencesGraph`\
     This attribute allows builders access to the references graph of
     their inputs. The attribute is a list of inputs in the Nix store
     whose references graph the builder needs to know. The value of
@@ -65,17 +65,17 @@ Derivations can declare some infrequently used optional attributes.
     files have the format used by `nix-store --register-validity`
     (with the deriver fields left empty). For example, when the
     following derivation is built:
-    
+
     ```nix
     derivation {
       ...
       exportReferencesGraph = [ "libfoo-graph" libfoo ];
     };
     ```
-    
+
     the references graph of `libfoo` is placed in the file
     `libfoo-graph` in the temporary build directory.
-    
+
     `exportReferencesGraph` is useful for builders that want to do
     something with the closure of a store path. Examples include the
     builders in NixOS that generate the initial ramdisk for booting
@@ -84,66 +84,66 @@ Derivations can declare some infrequently used optional attributes.
     with a Nix store containing the closure of a bootable NixOS
     configuration).
 
-  - `impureEnvVars`  
+  - `impureEnvVars`\
     This attribute allows you to specify a list of environment variables
     that should be passed from the environment of the calling user to
     the builder. Usually, the environment is cleared completely when the
     builder is executed, but with this attribute you can allow specific
     environment variables to be passed unmodified. For example,
     `fetchurl` in Nixpkgs has the line
-    
+
     ```nix
     impureEnvVars = [ "http_proxy" "https_proxy" ... ];
     ```
-    
+
     to make it use the proxy server configuration specified by the user
     in the environment variables `http_proxy` and friends.
-    
+
     This attribute is only allowed in *fixed-output derivations* (see
     below), where impurities such as these are okay since (the hash
     of) the output is known in advance. It is ignored for all other
     derivations.
-    
+
     > **Warning**
-    > 
+    >
     > `impureEnvVars` implementation takes environment variables from
     > the current builder process. When a daemon is building its
     > environmental variables are used. Without the daemon, the
     > environmental variables come from the environment of the
     > `nix-build`.
 
-  - `outputHash`; `outputHashAlgo`; `outputHashMode`  
+  - `outputHash`; `outputHashAlgo`; `outputHashMode`\
     These attributes declare that the derivation is a so-called
     *fixed-output derivation*, which means that a cryptographic hash of
     the output is already known in advance. When the build of a
     fixed-output derivation finishes, Nix computes the cryptographic
     hash of the output and compares it to the hash declared with these
     attributes. If there is a mismatch, the build fails.
-    
+
     The rationale for fixed-output derivations is derivations such as
     those produced by the `fetchurl` function. This function downloads a
     file from a given URL. To ensure that the downloaded file has not
     been modified, the caller must also specify a cryptographic hash of
     the file. For example,
-    
+
     ```nix
     fetchurl {
       url = "http://ftp.gnu.org/pub/gnu/hello/hello-2.1.1.tar.gz";
       sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465";
     }
     ```
-    
+
     It sometimes happens that the URL of the file changes, e.g., because
     servers are reorganised or no longer available. We then must update
     the call to `fetchurl`, e.g.,
-    
+
     ```nix
     fetchurl {
       url = "ftp://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz";
       sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465";
     }
     ```
-    
+
     If a `fetchurl` derivation was treated like a normal derivation, the
     output paths of the derivation and *all derivations depending on it*
     would change. For instance, if we were to change the URL of the
@@ -151,16 +151,16 @@ Derivations can declare some infrequently used optional attributes.
     other packages depend) massive rebuilds would be needed. This is
     unfortunate for a change which we know cannot have a real effect as
     it propagates upwards through the dependency graph.
-    
+
     For fixed-output derivations, on the other hand, the name of the
     output path only depends on the `outputHash*` and `name` attributes,
     while all other attributes are ignored for the purpose of computing
     the output path. (The `name` attribute is included because it is
     part of the path.)
-    
+
     As an example, here is the (simplified) Nix expression for
     `fetchurl`:
-    
+
     ```nix
     { stdenv, curl }: # The curl program is used for downloading.
 
@@ -180,43 +180,51 @@ Derivations can declare some infrequently used optional attributes.
       inherit url;
     }
     ```
-    
+
     The `outputHashAlgo` attribute specifies the hash algorithm used to
     compute the hash. It can currently be `"sha1"`, `"sha256"` or
     `"sha512"`.
-    
+
     The `outputHashMode` attribute determines how the hash is computed.
     It must be one of the following two values:
-    
-      - `"flat"`  
+
+      - `"flat"`\
         The output must be a non-executable regular file. If it isn’t,
         the build fails. The hash is simply computed over the contents
         of that file (so it’s equal to what Unix commands like
         `sha256sum` or `sha1sum` produce).
-        
+
         This is the default.
-    
-      - `"recursive"`  
+
+      - `"recursive"`\
         The hash is computed over the NAR archive dump of the output
         (i.e., the result of [`nix-store
         --dump`](../command-ref/nix-store.md#operation---dump)). In
         this case, the output can be anything, including a directory
         tree.
-    
+
     The `outputHash` attribute, finally, must be a string containing
     the hash in either hexadecimal or base-32 notation. (See the
     [`nix-hash` command](../command-ref/nix-hash.md) for information
     about converting to and from base-32 notation.)
+    
+  - `__contentAddressed`
+    If this **experimental** attribute is set to true, then the derivation
+    outputs will be stored in a content-addressed location rather than the
+    traditional input-addressed one.
+    This only has an effect if the `ca-derivation` experimental feature is enabled.
+    
+    Setting this attribute also requires setting `outputHashMode` and `outputHashAlgo` like for *fixed-output derivations* (see above).
 
-  - `passAsFile`  
+  - `passAsFile`\
     A list of names of attributes that should be passed via files rather
     than environment variables. For example, if you have
-    
+
     ```nix
     passAsFile = ["big"];
     big = "a very long string";
     ```
-    
+
     then when the builder runs, the environment variable `bigPath`
     will contain the absolute path to a temporary file containing `a
     very long string`. That is, for any attribute *x* listed in
@@ -226,7 +234,7 @@ Derivations can declare some infrequently used optional attributes.
     builder, since most operating systems impose a limit on the size
     of the environment (typically, a few hundred kilobyte).
 
-  - `preferLocalBuild`  
+  - `preferLocalBuild`\
     If this attribute is set to `true` and [distributed building is
     enabled](../advanced-topics/distributed-builds.md), then, if
     possible, the derivaton will be built locally instead of forwarded
@@ -234,14 +242,14 @@ Derivations can declare some infrequently used optional attributes.
     where the cost of doing a download or remote build would exceed
     the cost of building locally.
 
-  - `allowSubstitutes`  
+  - `allowSubstitutes`\
     If this attribute is set to `false`, then Nix will always build this
     derivation; it will not try to substitute its outputs. This is
     useful for very trivial derivations (such as `writeText` in Nixpkgs)
     that are cheaper to build than to substitute from a binary cache.
-    
+
     > **Note**
-    > 
+    >
     > You need to have a builder configured which satisfies the
     > derivation’s `system` attribute, since the derivation cannot be
     > substituted. Thus it is usually a good idea to align `system` with

doc/manual/src/expressions/builtin-constants.md

@@ -2,7 +2,7 @@
 
 Here are the constants built into the Nix expression evaluator:
 
-  - `builtins`  
+  - `builtins`\
     The set `builtins` contains all the built-in functions and values.
     You can use `builtins` to test for the availability of features in
     the Nix installation, e.g.,
@@ -14,7 +14,7 @@ Here are the constants built into the Nix expression evaluator:
     This allows a Nix expression to fall back gracefully on older Nix
     installations that don’t have the desired built-in function.
 
-  - `builtins.currentSystem`  
+  - `builtins.currentSystem`\
     The built-in value `currentSystem` evaluates to the Nix platform
     identifier for the Nix installation on which the expression is being
     evaluated, such as `"i686-linux"` or `"x86_64-darwin"`.

doc/manual/src/expressions/builtins-prefix.md

@@ -9,7 +9,8 @@ scope. Instead, you can access them through the `builtins` built-in
 value, which is a set that contains all built-in functions and values.
 For instance, `derivation` is also available as `builtins.derivation`.
 
-  - `derivation` *attrs*; `builtins.derivation` *attrs*  
-
-    `derivation` is described in [its own section](derivations.md).
-
+<dl>
+  <dt><code>derivation <var>attrs</var></code>;
+      <code>builtins.derivation <var>attrs</var></code></dt>
+  <dd><p><var>derivation</var> in described in
+         <a href="derivations.md">its own section</a>.</p></dd>

doc/manual/src/expressions/builtins-suffix.md

@@ -0,0 +1 @@
+</dl>

doc/manual/src/expressions/language-values.md

@@ -139,6 +139,13 @@ Nix has the following basic data types:
     environment variable `NIX_PATH` will be searched for the given file
     or directory name.
 
+    Antiquotation is supported in any paths except those in angle brackets.
+    `./${foo}-${bar}.nix` is a more convenient way of writing 
+    `./. + "/" + foo + "-" + bar + ".nix"` or `./. + "/${foo}-${bar}.nix"`. At
+    least one slash must appear *before* any antiquotations for this to be
+    recognized as a path. `a.${foo}/b.${bar}` is a syntactically valid division
+    operation. `./a.${foo}/b.${bar}` is a path.
+
   - *Booleans* with values `true` and `false`.
 
   - The null value, denoted as `null`.

doc/manual/src/glossary.md

@@ -1,48 +1,48 @@
 # Glossary
 
-  - derivation  
+  - derivation\
     A description of a build action. The result of a derivation is a
     store object. Derivations are typically specified in Nix expressions
     using the [`derivation` primitive](expressions/derivations.md). These are
     translated into low-level *store derivations* (implicitly by
     `nix-env` and `nix-build`, or explicitly by `nix-instantiate`).
 
-  - store  
+  - store\
     The location in the file system where store objects live. Typically
     `/nix/store`.
 
-  - store path  
+  - store path\
     The location in the file system of a store object, i.e., an
     immediate child of the Nix store directory.
 
-  - store object  
+  - store object\
     A file that is an immediate child of the Nix store directory. These
     can be regular files, but also entire directory trees. Store objects
     can be sources (objects copied from outside of the store),
     derivation outputs (objects produced by running a build action), or
     derivations (files describing a build action).
 
-  - substitute  
+  - substitute\
     A substitute is a command invocation stored in the Nix database that
     describes how to build a store object, bypassing the normal build
     mechanism (i.e., derivations). Typically, the substitute builds the
     store object by downloading a pre-built version of the store object
     from some server.
 
-  - purity  
+  - purity\
     The assumption that equal Nix derivations when run always produce
     the same output. This cannot be guaranteed in general (e.g., a
     builder can rely on external inputs such as the network or the
     system time) but the Nix model assumes it.
 
-  - Nix expression  
+  - Nix expression\
     A high-level description of software packages and compositions
     thereof. Deploying software using Nix entails writing Nix
     expressions for your packages. Nix expressions are translated to
     derivations that are stored in the Nix store. These derivations can
     then be built.
 
-  - reference  
+  - reference\
     A store path `P` is said to have a reference to a store path `Q` if
     the store object at `P` contains the path `Q` somewhere. The
     *references* of a store path are the set of store paths to which it
@@ -52,11 +52,11 @@
     output paths), whereas an output path only references other output
     paths.
 
-  - reachable  
+  - reachable\
     A store path `Q` is reachable from another store path `P` if `Q`
     is in the *closure* of the *references* relation.
 
-  - closure  
+  - closure\
     The closure of a store path is the set of store paths that are
     directly or indirectly “reachable” from that store path; that is,
     it’s the closure of the path under the *references* relation. For
@@ -71,29 +71,29 @@
     to path `Q`, then `Q` is in the closure of `P`. Further, if `Q`
     references `R` then `R` is also in the closure of `P`.
 
-  - output path  
+  - output path\
     A store path produced by a derivation.
 
-  - deriver  
+  - deriver\
     The deriver of an *output path* is the store
     derivation that built it.
 
-  - validity  
+  - validity\
     A store path is considered *valid* if it exists in the file system,
     is listed in the Nix database as being valid, and if all paths in
     its closure are also valid.
 
-  - user environment  
+  - user environment\
     An automatically generated store object that consists of a set of
     symlinks to “active” applications, i.e., other store paths. These
     are generated automatically by
     [`nix-env`](command-ref/nix-env.md). See *profiles*.
 
-  - profile  
+  - profile\
     A symlink to the current *user environment* of a user, e.g.,
     `/nix/var/nix/profiles/default`.
 
-  - NAR  
+  - NAR\
     A *N*ix *AR*chive. This is a serialisation of a path in the Nix
     store. It can contain regular files, directories and symbolic
     links.  NARs are generated and unpacked using `nix-store --dump`

doc/manual/src/installation/env-variables.md

@@ -40,7 +40,7 @@ export NIX_SSL_CERT_FILE=/etc/ssl/my-certificate-bundle.crt
 > **Note**
 > 
 > You must not add the export and then do the install, as the Nix
-> installer will detect the presense of Nix configuration, and abort.
+> installer will detect the presence of Nix configuration, and abort.
 
 ## `NIX_SSL_CERT_FILE` with macOS and the Nix daemon
 

doc/manual/src/installation/installing-binary.md

@@ -1,18 +1,26 @@
 # Installing a Binary Distribution
 
-If you are using Linux or macOS versions up to 10.14 (Mojave), the
-easiest way to install Nix is to run the following command:
+The easiest way to install Nix is to run the following command:
 
 ```console
 $ sh <(curl -L https://nixos.org/nix/install)
 ```
 
-If you're using macOS 10.15 (Catalina) or newer, consult [the macOS
-installation instructions](#macos-installation) before installing.
+This will run the installer interactively (causing it to explain what
+it is doing more explicitly), and perform the default "type" of install
+for your platform:
+- single-user on Linux
+- multi-user on macOS
 
-As of Nix 2.1.0, the Nix installer will always default to creating a
-single-user installation, however opting in to the multi-user
-installation is highly recommended.
+  > **Notes on read-only filesystem root in macOS 10.15 Catalina +**
+  > 
+  > - It took some time to support this cleanly. You may see posts,
+  >   examples, and tutorials using obsolete workarounds.
+  > - Supporting it cleanly made macOS installs too complex to qualify
+  >   as single-user, so this type is no longer supported on macOS.
+
+We recommend the multi-user install if it supports your platform and
+you can authenticate with `sudo`.
 
 # Single User Installation
 
@@ -50,9 +58,9 @@ $ rm -rf /nix
 The multi-user Nix installation creates system users, and a system
 service for the Nix daemon.
 
-  - Linux running systemd, with SELinux disabled
-
-  - macOS
+**Supported Systems**
+- Linux running systemd, with SELinux disabled
+- macOS
 
 You can instruct the installer to perform a multi-user installation on
 your system:
@@ -96,165 +104,28 @@ sudo rm /Library/LaunchDaemons/org.nixos.nix-daemon.plist
 There may also be references to Nix in `/etc/profile`, `/etc/bashrc`,
 and `/etc/zshrc` which you may remove.
 
-# macOS Installation
+# macOS Installation <a name="sect-macos-installation-change-store-prefix"></a><a name="sect-macos-installation-encrypted-volume"></a><a name="sect-macos-installation-symlink"></a><a name="sect-macos-installation-recommended-notes"></a>
+<!-- Note: anchors above to catch permalinks to old explanations -->
 
-Starting with macOS 10.15 (Catalina), the root filesystem is read-only.
-This means `/nix` can no longer live on your system volume, and that
-you'll need a workaround to install Nix.
+We believe we have ironed out how to cleanly support the read-only root
+on modern macOS. New installs will do this automatically, and you can
+also re-run a new installer to convert your existing setup.
 
-The recommended approach, which creates an unencrypted APFS volume for
-your Nix store and a "synthetic" empty directory to mount it over at
-`/nix`, is least likely to impair Nix or your system.
+This section previously detailed the situation, options, and trade-offs,
+but it now only outlines what the installer does. You don't need to know
+this to run the installer, but it may help if you run into trouble:
 
-> **Note**
-> 
-> With all separate-volume approaches, it's possible something on your
-> system (particularly daemons/services and restored apps) may need
-> access to your Nix store before the volume is mounted. Adding
-> additional encryption makes this more likely.
-
-If you're using a recent Mac with a [T2
-chip](https://www.apple.com/euro/mac/shared/docs/Apple_T2_Security_Chip_Overview.pdf),
-your drive will still be encrypted at rest (in which case "unencrypted"
-is a bit of a misnomer). To use this approach, just install Nix with:
-
-```console
-$ sh <(curl -L https://nixos.org/nix/install) --darwin-use-unencrypted-nix-store-volume
-```
-
-If you don't like the sound of this, you'll want to weigh the other
-approaches and tradeoffs detailed in this section.
-
-> **Note**
-> 
-> All of the known workarounds have drawbacks, but we hope better
-> solutions will be available in the future. Some that we have our eye
-> on are:
-> 
-> 1.  A true firmlink would enable the Nix store to live on the primary
->     data volume without the build problems caused by the symlink
->     approach. End users cannot currently create true firmlinks.
-> 
-> 2.  If the Nix store volume shared FileVault encryption with the
->     primary data volume (probably by using the same volume group and
->     role), FileVault encryption could be easily supported by the
->     installer without requiring manual setup by each user.
-
-## Change the Nix store path prefix
-
-Changing the default prefix for the Nix store is a simple approach which
-enables you to leave it on your root volume, where it can take full
-advantage of FileVault encryption if enabled. Unfortunately, this
-approach also opts your device out of some benefits that are enabled by
-using the same prefix across systems:
-
-  - Your system won't be able to take advantage of the binary cache
-    (unless someone is able to stand up and support duplicate caching
-    infrastructure), which means you'll spend more time waiting for
-    builds.
-
-  - It's harder to build and deploy packages to Linux systems.
-
-It would also possible (and often requested) to just apply this change
-ecosystem-wide, but it's an intrusive process that has side effects we
-want to avoid for now.
-
-## Use a separate encrypted volume
-
-If you like, you can also add encryption to the recommended approach
-taken by the installer. You can do this by pre-creating an encrypted
-volume before you run the installer--or you can run the installer and
-encrypt the volume it creates later.
-
-In either case, adding encryption to a second volume isn't quite as
-simple as enabling FileVault for your boot volume. Before you dive in,
-there are a few things to weigh:
-
-1.  The additional volume won't be encrypted with your existing
-    FileVault key, so you'll need another mechanism to decrypt the
-    volume.
-
-2.  You can store the password in Keychain to automatically decrypt the
-    volume on boot--but it'll have to wait on Keychain and may not mount
-    before your GUI apps restore. If any of your launchd agents or apps
-    depend on Nix-installed software (for example, if you use a
-    Nix-installed login shell), the restore may fail or break.
-    
-    On a case-by-case basis, you may be able to work around this problem
-    by using `wait4path` to block execution until your executable is
-    available.
-    
-    It's also possible to decrypt and mount the volume earlier with a
-    login hook--but this mechanism appears to be deprecated and its
-    future is unclear.
-
-3.  You can hard-code the password in the clear, so that your store
-    volume can be decrypted before Keychain is available.
-
-If you are comfortable navigating these tradeoffs, you can encrypt the
-volume with something along the lines of:
-
-```console
-$ diskutil apfs enableFileVault /nix -user disk
-```
-
-## Symlink the Nix store to a custom location
-
-Another simple approach is using `/etc/synthetic.conf` to symlink the
-Nix store to the data volume. This option also enables your store to
-share any configured FileVault encryption. Unfortunately, builds that
-resolve the symlink may leak the canonical path or even fail.
-
-Because of these downsides, we can't recommend this approach.
-
-## Notes on the recommended approach
-
-This section goes into a little more detail on the recommended approach.
-You don't need to understand it to run the installer, but it can serve
-as a helpful reference if you run into trouble.
-
-1.  In order to compose user-writable locations into the new read-only
-    system root, Apple introduced a new concept called `firmlinks`,
-    which it describes as a "bi-directional wormhole" between two
-    filesystems. You can see the current firmlinks in
-    `/usr/share/firmlinks`. Unfortunately, firmlinks aren't (currently?)
-    user-configurable.
-    
-    For special cases like NFS mount points or package manager roots,
-    [synthetic.conf(5)](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man5/synthetic.conf.5.html)
-    supports limited user-controlled file-creation (of symlinks, and
-    synthetic empty directories) at `/`. To create a synthetic empty
-    directory for mounting at `/nix`, add the following line to
-    `/etc/synthetic.conf` (create it if necessary):
-    
-        nix
-
-2.  This configuration is applied at boot time, but you can use
-    `apfs.util` to trigger creation (not deletion) of new entries
-    without a reboot:
-    
-    ```console
-    $ /System/Library/Filesystems/apfs.fs/Contents/Resources/apfs.util -B
-    ```
-
-3.  Create the new APFS volume with diskutil:
-    
-    ```console
-    $ sudo diskutil apfs addVolume diskX APFS 'Nix Store' -mountpoint /nix
-    ```
-
-4.  Using `vifs`, add the new mount to `/etc/fstab`. If it doesn't
-    already have other entries, it should look something like:
-    
-        #
-        # Warning - this file should only be modified with vifs(8)
-        #
-        # Failure to do so is unsupported and may be destructive.
-        #
-        LABEL=Nix\040Store /nix apfs rw,nobrowse
-    
-    The nobrowse setting will keep Spotlight from indexing this volume,
-    and keep it from showing up on your desktop.
+- create a new APFS volume for your Nix store
+- update `/etc/synthetic.conf` to direct macOS to create a "synthetic"
+  empty root directory to mount your volume
+- specify mount options for the volume in `/etc/fstab`
+- if you have FileVault enabled
+    - generate an encryption password
+    - put it in your system Keychain
+    - use it to encrypt the volume
+- create a system LaunchDaemon to mount this volume early enough in the
+  boot process to avoid problems loading or restoring any programs that
+  need access to your Nix store
 
 # Installing a pinned Nix version from a URL
 

doc/manual/src/installation/prerequisites-source.md

@@ -26,15 +26,6 @@
     available for download from the official repository
     <https://github.com/google/brotli>.
 
-  - The bzip2 compressor program and the `libbz2` library. Thus you must
-    have bzip2 installed, including development headers and libraries.
-    If your distribution does not provide these, you can obtain bzip2
-    from
-    <https://sourceware.org/bzip2/>.
-
-  - `liblzma`, which is provided by XZ Utils. If your distribution does
-    not provide this, you can get it from <https://tukaani.org/xz/>.
-
   - cURL and its library. If your distribution does not provide it, you
     can get it from <https://curl.haxx.se/>.
 

doc/manual/src/package-management/s3-substituter.md

@@ -7,17 +7,17 @@ cache mechanism that Nix usually uses to fetch prebuilt binaries from
 
 The following options can be specified as URL parameters to the S3 URL:
 
-  - `profile`  
+  - `profile`\
     The name of the AWS configuration profile to use. By default Nix
     will use the `default` profile.
 
-  - `region`  
+  - `region`\
     The region of the S3 bucket. `us–east-1` by default.
     
     If your bucket is not in `us–east-1`, you should always explicitly
     specify the region parameter.
 
-  - `endpoint`  
+  - `endpoint`\
     The URL to your S3-compatible service, for when not using Amazon S3.
     Do not specify this value if you're using Amazon S3.
     
@@ -26,7 +26,7 @@ The following options can be specified as URL parameters to the S3 URL:
     > This endpoint must support HTTPS and will use path-based
     > addressing instead of virtual host based addressing.
 
-  - `scheme`  
+  - `scheme`\
     The scheme used for S3 requests, `https` (default) or `http`. This
     option allows you to disable HTTPS for binary caches which don't
     support it.

doc/manual/src/release-notes/rl-2.4.md

@@ -0,0 +1,525 @@
+# Release 2.4 (2021-11-01)
+
+This is the first release in more than two years and is the result of
+more than 2800 commits from 195 contributors since release 2.3.
+
+## Highlights
+
+* Nix's **error messages** have been improved a lot. For instance,
+  evaluation errors now point out the location of the error:
+
+  ```
+  $ nix build
+  error: undefined variable 'bzip3'
+
+         at /nix/store/449lv242z0zsgwv95a8124xi11sp419f-source/flake.nix:88:13:
+
+             87|           [ curl
+             88|             bzip3 xz brotli editline
+               |             ^
+             89|             openssl sqlite
+  ```
+
+* The **`nix` command** has seen a lot of work and is now almost at
+  feature parity with the old command-line interface (the `nix-*`
+  commands). It aims to be [more modern, consistent and pleasant to
+  use](../contributing/cli-guideline.md) than the old CLI. It is still
+  marked as experimental but its interface should not change much
+  anymore in future releases.
+
+* **Flakes** are a new format to package Nix-based projects in a more
+  discoverable, composable, consistent and reproducible way. A flake
+  is just a repository or tarball containing a file named `flake.nix`
+  that specifies dependencies on other flakes and returns any Nix
+  assets such as packages, Nixpkgs overlays, NixOS modules or CI
+  tests. The new `nix` CLI is primarily based around flakes; for
+  example, a command like `nix run nixpkgs#hello` runs the `hello`
+  application from the `nixpkgs` flake.
+
+  Flakes are currently marked as experimental. For an introduction,
+  see [this blog
+  post](https://www.tweag.io/blog/2020-05-25-flakes/). For detailed
+  information about flake syntax and semantics, see the [`nix flake`
+  manual page](../command-ref/new-cli/nix3-flake.md).
+
+* Nix's store can now be **content-addressed**, meaning that the hash
+  component of a store path is the hash of the path's
+  contents. Previously Nix could only build **input-addressed** store
+  paths, where the hash is computed from the derivation dependency
+  graph. Content-addressing allows deduplication, early cutoff in
+  build systems, and unprivileged closure copying. This is still [an
+  experimental
+  feature](https://discourse.nixos.org/t/content-addressed-nix-call-for-testers/12881).
+
+* The Nix manual has been converted into Markdown, making it easier to
+  contribute. In addition, every `nix` subcommand now has a manual
+  page, documenting every option.
+
+* A new setting that allows **experimental features** to be enabled
+  selectively. This allows us to merge unstable features into Nix more
+  quickly and do more frequent releases.
+
+## Other features
+
+* There are many new `nix` subcommands:
+
+  - `nix develop` is intended to replace `nix-shell`. It has a number
+    of new features:
+
+    * It automatically sets the output environment variables (such as
+      `$out`) to writable locations (such as `./outputs/out`).
+
+    * It can store the environment in a profile. This is useful for
+      offline work.
+
+    * It can run specific phases directly. For instance, `nix develop
+      --build` runs `buildPhase`.
+
+    - It allows dependencies in the Nix store to be "redirected" to
+      arbitrary directories using the `--redirect` flag. This is
+      useful if you want to hack on a package *and* some of its
+      dependencies at the same time.
+
+  - `nix print-dev-env` prints the environment variables and bash
+    functions defined by a derivation. This is useful for users of
+    other shells than bash (especially with `--json`).
+
+  - `nix shell` was previously named `nix run` and is intended to
+    replace `nix-shell -p`, but without the `stdenv` overhead. It
+    simply starts a shell where some packages have been added to
+    `$PATH`.
+
+  - `nix run` (not to be confused with the old subcommand that has
+    been renamed to `nix shell`) runs an "app", a flake output that
+    specifies a command to run, or an eponymous program from a
+    package. For example, `nix run nixpkgs#hello` runs the `hello`
+    program from the `hello` package in `nixpkgs`.
+
+  - `nix flake` is the container for flake-related operations, such as
+    creating a new flake, querying the contents of a flake or updating
+    flake lock files.
+
+  - `nix registry` allows you to query and update the flake registry,
+    which maps identifiers such as `nixpkgs` to concrete flake URLs.
+
+  - `nix profile` is intended to replace `nix-env`. Its main advantage
+    is that it keeps track of the provenance of installed packages
+    (e.g. exactly which flake version a package came from). It also
+    has some helpful subcommands:
+
+    * `nix profile history` shows what packages were added, upgraded
+      or removed between each version of a profile.
+
+    * `nix profile diff-closures` shows the changes between the
+      closures of each version of a profile. This allows you to
+      discover the addition or removal of dependencies or size
+      changes.
+
+    **Warning**: after a profile has been updated using `nix profile`,
+    it is no longer usable with `nix-env`.
+
+  - `nix store diff-closures` shows the differences between the
+    closures of two store paths in terms of the versions and sizes of
+    dependencies in the closures.
+
+  - `nix store make-content-addressable` rewrites an arbitrary closure
+    to make it content-addressed. Such paths can be copied into other
+    stores without requiring signatures.
+
+  - `nix bundle` uses the [`nix-bundle`
+    program](https://github.com/matthewbauer/nix-bundle) to convert a
+    closure into a self-extracting executable.
+
+  - Various other replacements for the old CLI, e.g. `nix store gc`,
+    `nix store delete`, `nix store repair`, `nix nar dump-path`, `nix
+    store prefetch-file`, `nix store prefetch-tarball`, `nix key` and
+    `nix daemon`.
+
+* Nix now has an **evaluation cache** for flake outputs. For example,
+  a second invocation of the command `nix run nixpkgs#firefox` will
+  not need to evaluate the `firefox` attribute because it's already in
+  the evaluation cache. This is made possible by the hermetic
+  evaluation model of flakes.
+
+* The new `--offline` flag disables substituters and causes all
+  locally cached tarballs and repositories to be considered
+  up-to-date.
+
+* The new `--refresh` flag causes all locally cached tarballs and
+  repositories to be considered out-of-date.
+
+* Many `nix` subcommands now have a `--json` option to produce
+  machine-readable output.
+
+* `nix repl` has a new `:doc` command to show documentation about
+  builtin functions (e.g. `:doc builtins.map`).
+
+* Binary cache stores now have an option `index-debug-info` to create
+  an index of DWARF debuginfo files for use by
+  [`dwarffs`](https://github.com/edolstra/dwarffs).
+
+* To support flakes, Nix now has an extensible mechanism for fetching
+  source trees. Currently it has the following backends:
+
+  * Git repositories
+
+  * Mercurial repositories
+
+  * GitHub and GitLab repositories (an optimisation for faster
+    fetching than Git)
+
+  * Tarballs
+
+  * Arbitrary directories
+
+  The fetcher infrastructure is exposed via flake input specifications
+  and via the `fetchTree` built-in.
+
+* **Languages changes**: the only new language feature is that you can
+  now have antiquotations in paths, e.g. `./${foo}` instead of `./. +
+  foo`.
+
+* **New built-in functions**:
+
+  - `builtins.fetchTree` allows fetching a source tree using any
+    backends supported by the fetcher infrastructure. It subsumes the
+    functionality of existing built-ins like `fetchGit`,
+    `fetchMercurial` and `fetchTarball`.
+
+  - `builtins.getFlake` fetches a flake and returns its output
+    attributes. This function should not be used inside flakes! Use
+    flake inputs instead.
+
+  - `builtins.floor` and `builtins.ceil` round a floating-point number
+    down and up, respectively.
+
+* Experimental support for recursive Nix. This means that Nix
+  derivations can now call Nix to build other derivations. This is not
+  in a stable state yet and not well
+  [documented](https://github.com/NixOS/nix/commit/c4d7c76b641d82b2696fef73ce0ac160043c18da).
+
+* The new experimental feature `no-url-literals` disables URL
+  literals. This helps to implement [RFC
+  45](https://github.com/NixOS/rfcs/pull/45).
+
+* Nix now uses `libarchive` to decompress and unpack tarballs and zip
+  files, so `tar` is no longer required.
+
+* The priority of substituters can now be overridden using the
+  `priority` substituter setting (e.g. `--substituters
+  'http://cache.nixos.org?priority=100 daemon?priority=10'`).
+
+* `nix edit` now supports non-derivation attributes, e.g. `nix edit
+  .#nixosConfigurations.bla`.
+
+* The `nix` command now provides command line completion for `bash`,
+  `zsh` and `fish`. Since the support for getting completions is built
+  into `nix`, it's easy to add support for other shells.
+
+* The new `--log-format` flag selects what Nix's output looks like. It
+  defaults to a terse progress indicator. There is a new
+  `internal-json` output format for use by other programs.
+
+* `nix eval` has a new `--apply` flag that applies a function to the
+  evaluation result.
+
+* `nix eval` has a new `--write-to` flag that allows it to write a
+  nested attribute set of string leaves to a corresponding directory
+  tree.
+
+* Memory improvements: many operations that add paths to the store or
+  copy paths between stores now run in constant memory.
+
+* Many `nix` commands now support the flag `--derivation` to operate
+  on a `.drv` file itself instead of its outputs.
+
+* There is a new store called `dummy://` that does not support
+  building or adding paths. This is useful if you want to use the Nix
+  evaluator but don't have a Nix store.
+
+* The `ssh-ng://` store now allows substituting paths on the remote,
+  as `ssh://` already did.
+
+* When auto-calling a function with an ellipsis, all arguments are now
+  passed.
+
+* New `nix-shell` features:
+
+  - It preserves the `PS1` environment variable if
+    `NIX_SHELL_PRESERVE_PROMPT` is set.
+
+  - With `-p`, it passes any `--arg`s as Nixpkgs arguments.
+
+  - Support for structured attributes.
+
+* `nix-prefetch-url` has a new `--executable` flag.
+
+* On `x86_64` systems, [`x86_64` microarchitecture
+  levels](https://lwn.net/Articles/844831/) are mapped to additional
+  system types (e.g. `x86_64-v1-linux`).
+
+* The new `--eval-store` flag allows you to use a different store for
+  evaluation than for building or storing the build result. This is
+  primarily useful when you want to query whether something exists in
+  a read-only store, such as a binary cache:
+
+  ```
+  # nix path-info --json --store https://cache.nixos.org \
+    --eval-store auto nixpkgs#hello
+  ```
+
+  (Here `auto` indicates the local store.)
+
+* The Nix daemon has a new low-latency mechanism for copying
+  closures. This is useful when building on remote stores such as
+  `ssh-ng://`.
+
+* Plugins can now register `nix` subcommands.
+
+## Incompatible changes
+
+* The `nix` command is now marked as an experimental feature. This
+  means that you need to add
+
+  > experimental-features = nix-command
+
+  to your `nix.conf` if you want to use it, or pass
+  `--extra-experimental-features nix-command` on the command line.
+
+* The `nix` command no longer has a syntax for referring to packages
+  in a channel. This means that the following no longer works:
+
+  > nix build nixpkgs.hello # Nix 2.3
+
+  Instead, you can either use the `#` syntax to select a package from
+  a flake, e.g.
+
+  > nix build nixpkgs#hello
+
+  Or, if you want to use the `nixpkgs` channel in the `NIX_PATH`
+  environment variable:
+
+  > nix build -f '<nixpkgs>' hello
+
+* The old `nix run` has been renamed to `nix shell`, while there is a
+  new `nix run` that runs a default command. So instead of
+
+  > nix run nixpkgs.hello -c hello # Nix 2.3
+
+  you should use
+
+  > nix shell nixpkgs#hello -c hello
+
+  or just
+
+  > nix run nixpkgs#hello
+
+  if the command you want to run has the same name as the package.
+
+* It is now an error to modify the `plugin-files` setting via a
+  command-line flag that appears after the first non-flag argument to
+  any command, including a subcommand to `nix`. For example,
+  `nix-instantiate default.nix --plugin-files ""` must now become
+  `nix-instantiate --plugin-files "" default.nix`.
+
+* We no longer release source tarballs. If you want to build from
+  source, please build from the tags in the Git repository.
+
+## Contributors
+
+This release has contributions from
+Adam Höse,
+Albert Safin,
+Alex Kovar,
+Alex Zero,
+Alexander Bantyev,
+Alexandre Esteves,
+Alyssa Ross,
+Anatole Lucet,
+Anders Kaseorg,
+Andreas Rammhold,
+Antoine Eiche,
+Antoine Martin,
+Arnout Engelen,
+Arthur Gautier,
+aszlig,
+Ben Burdette,
+Benjamin Hipple,
+Bernardo Meurer,
+Björn Gohla,
+Bjørn Forsman,
+Bob van der Linden,
+Brian Leung,
+Brian McKenna,
+Brian Wignall,
+Bruce Toll,
+Bryan Richter,
+Calle Rosenquist,
+Calvin Loncaric,
+Carlo Nucera,
+Carlos D'Agostino,
+Chaz Schlarp,
+Christian Höppner,
+Christian Kampka,
+Chua Hou,
+Chuck,
+Cole Helbling,
+Daiderd Jordan,
+Dan Callahan,
+Dani,
+Daniel Fitzpatrick,
+Danila Fedorin,
+Daniël de Kok,
+Danny Bautista,
+DavHau,
+David McFarland,
+Dima,
+Domen Kožar,
+Dominik Schrempf,
+Dominique Martinet,
+dramforever,
+Dustin DeWeese,
+edef,
+Eelco Dolstra,
+Emilio Karakey,
+Emily,
+Eric Culp,
+Ersin Akinci,
+Fabian Möller,
+Farid Zakaria,
+Federico Pellegrin,
+Finn Behrens,
+Florian Franzen,
+Félix Baylac-Jacqué,
+Gabriel Gonzalez,
+Geoff Reedy,
+Georges Dubus,
+Graham Christensen,
+Greg Hale,
+Greg Price,
+Gregor Kleen,
+Gregory Hale,
+Griffin Smith,
+Guillaume Bouchard,
+Harald van Dijk,
+illustris,
+Ivan Zvonimir Horvat,
+Jade,
+Jake Waksbaum,
+jakobrs,
+James Ottaway,
+Jan Tojnar,
+Janne Heß,
+Jaroslavas Pocepko,
+Jarrett Keifer,
+Jeremy Schlatter,
+Joachim Breitner,
+Joe Hermaszewski,
+Joe Pea,
+John Ericson,
+Jonathan Ringer,
+Josef Kemetmüller,
+Joseph Lucas,
+Jude Taylor,
+Julian Stecklina,
+Julien Tanguy,
+Jörg Thalheim,
+Kai Wohlfahrt,
+keke,
+Keshav Kini,
+Kevin Quick,
+Kevin Stock,
+Kjetil Orbekk,
+Krzysztof Gogolewski,
+kvtb,
+Lars Mühmel,
+Leonhard Markert,
+Lily Ballard,
+Linus Heckemann,
+Lorenzo Manacorda,
+Lucas Desgouilles,
+Lucas Franceschino,
+Lucas Hoffmann,
+Luke Granger-Brown,
+Madeline Haraj,
+Marwan Aljubeh,
+Mat Marini,
+Mateusz Piotrowski,
+Matthew Bauer,
+Matthew Kenigsberg,
+Mauricio Scheffer,
+Maximilian Bosch,
+Michael Adler,
+Michael Bishop,
+Michael Fellinger,
+Michael Forney,
+Michael Reilly,
+mlatus,
+Mykola Orliuk,
+Nathan van Doorn,
+Naïm Favier,
+ng0,
+Nick Van den Broeck,
+Nicolas Stig124 Formichella,
+Niels Egberts,
+Niklas Hambüchen,
+Nikola Knezevic,
+oxalica,
+p01arst0rm,
+Pamplemousse,
+Patrick Hilhorst,
+Paul Opiyo,
+Pavol Rusnak,
+Peter Kolloch,
+Philipp Bartsch,
+Philipp Middendorf,
+Piotr Szubiakowski,
+Profpatsch,
+Puck Meerburg,
+Ricardo M. Correia,
+Rickard Nilsson,
+Robert Hensing,
+Robin Gloster,
+Rodrigo,
+Rok Garbas,
+Ronnie Ebrin,
+Rovanion Luckey,
+Ryan Burns,
+Ryan Mulligan,
+Ryne Everett,
+Sam Doshi,
+Sam Lidder,
+Samir Talwar,
+Samuel Dionne-Riel,
+Sebastian Ullrich,
+Sergei Trofimovich,
+Sevan Janiyan,
+Shao Cheng,
+Shea Levy,
+Silvan Mosberger,
+Stefan Frijters,
+Stefan Jaax,
+sternenseemann,
+Steven Shaw,
+Stéphan Kochen,
+SuperSandro2000,
+Suraj Barkale,
+Taeer Bar-Yam,
+Thomas Churchman,
+Théophane Hufschmitt,
+Timothy DeHerrera,
+Timothy Klim,
+Tobias Möst,
+Tobias Pflug,
+Tom Bereknyei,
+Travis A. Everett,
+Ujjwal Jain,
+Vladimír Čunát,
+Wil Taylor,
+Will Dietz,
+Yaroslav Bolyukin,
+Yestin L. Harrison,
+YI,
+Yorick van Pelt,
+Yuriy Taraday and
+zimbatm.

flake.lock

@@ -1,22 +1,39 @@
 {
   "nodes": {
+    "lowdown-src": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1633514407,
+        "narHash": "sha256-Dw32tiMjdK9t3ETl5fzGrutQTzh2rufgZV4A/BbxuD4=",
+        "owner": "kristapsdz",
+        "repo": "lowdown",
+        "rev": "d2c2b44ff6c27b936ec27358a2653caaef8f73b8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "kristapsdz",
+        "repo": "lowdown",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1602702596,
-        "narHash": "sha256-fqJ4UgOb4ZUnCDIapDb4gCrtAah5Rnr2/At3IzMitig=",
+        "lastModified": 1632864508,
+        "narHash": "sha256-d127FIvGR41XbVRDPVvozUPQ/uRHbHwvfyKHwEt5xFM=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ad0d20345219790533ebe06571f82ed6b034db31",
+        "rev": "82891b5e2c2359d7e58d08849e4c89511ab94234",
         "type": "github"
       },
       "original": {
         "id": "nixpkgs",
-        "ref": "nixos-20.09-small",
+        "ref": "nixos-21.05-small",
         "type": "indirect"
       }
     },
     "root": {
       "inputs": {
+        "lowdown-src": "lowdown-src",
         "nixpkgs": "nixpkgs"
       }
     }

flake.nix

@@ -1,10 +1,10 @@
 {
   description = "The purely functional package manager";
 
-  inputs.nixpkgs.url = "nixpkgs/nixos-20.09-small";
-  #inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
+  inputs.nixpkgs.url = "nixpkgs/nixos-21.05-small";
+  inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
 
-  outputs = { self, nixpkgs }:
+  outputs = { self, nixpkgs, lowdown-src }:
 
     let
 
@@ -14,11 +14,13 @@
         then ""
         else "pre${builtins.substring 0 8 (self.lastModifiedDate or self.lastModified or "19700101")}_${self.shortRev or "dirty"}";
 
-      officialRelease = false;
+      officialRelease = true;
 
       linux64BitSystems = [ "x86_64-linux" "aarch64-linux" ];
       linuxSystems = linux64BitSystems ++ [ "i686-linux" ];
-      systems = linuxSystems ++ [ "x86_64-darwin" ];
+      systems = linuxSystems ++ [ "x86_64-darwin" "aarch64-darwin" ];
+
+      crossSystems = [ "armv6l-linux" "armv7l-linux" ];
 
       forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f system);
 
@@ -68,7 +70,7 @@
           [
             buildPackages.bison
             buildPackages.flex
-            (lib.getBin buildPackages.lowdown)
+            (lib.getBin buildPackages.lowdown-nix)
             buildPackages.mdbook
             buildPackages.autoconf-archive
             buildPackages.autoreconfHook
@@ -76,22 +78,23 @@
 
             # Tests
             buildPackages.git
-            buildPackages.mercurial
+            buildPackages.mercurial # FIXME: remove? only needed for tests
             buildPackages.jq
-          ];
+          ]
+          ++ lib.optionals stdenv.hostPlatform.isLinux [(buildPackages.util-linuxMinimal or buildPackages.utillinuxMinimal)];
 
         buildDeps =
           [ curl
-            bzip2 xz brotli zlib editline
+            bzip2 xz brotli editline
             openssl sqlite
             libarchive
             boost
-            nlohmann_json
-            lowdown
+            lowdown-nix
             gmock
           ]
-          ++ lib.optionals stdenv.isLinux [libseccomp utillinuxMinimal]
-          ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium;
+          ++ lib.optionals stdenv.isLinux [libseccomp]
+          ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium
+          ++ lib.optional stdenv.hostPlatform.isx86_64 libcpuid;
 
         awsDeps = lib.optional (stdenv.isLinux || stdenv.isDarwin)
           (aws-sdk-cpp.override {
@@ -100,7 +103,13 @@
           });
 
         propagatedDeps =
-          [ (boehmgc.override { enableLargeConfig = true; })
+          [ ((boehmgc.override {
+              enableLargeConfig = true;
+            }).overrideAttrs(o: {
+              patches = (o.patches or []) ++ [
+                ./boehmgc-coroutine-sp-fallback.diff
+              ];
+            }))
           ];
 
         perlDeps =
@@ -109,12 +118,153 @@
           ];
       };
 
+    installScriptFor = systems:
+      with nixpkgsFor.x86_64-linux;
+        runCommand "installer-script"
+          { buildInputs = [ nix ];
+          }
+          ''
+            mkdir -p $out/nix-support
+
+            # Converts /nix/store/50p3qk8k...-nix-2.4pre20201102_550e11f/bin/nix to 50p3qk8k.../bin/nix.
+            tarballPath() {
+              # Remove the store prefix
+              local path=''${1#${builtins.storeDir}/}
+              # Get the path relative to the derivation root
+              local rest=''${path#*/}
+              # Get the derivation hash
+              local drvHash=''${path%%-*}
+              echo "$drvHash/$rest"
+            }
+
+            substitute ${./scripts/install.in} $out/install \
+              ${pkgs.lib.concatMapStrings
+                (system: let
+                    tarball = if builtins.elem system crossSystems then self.hydraJobs.binaryTarballCross.x86_64-linux.${system} else self.hydraJobs.binaryTarball.${system};
+                  in '' \
+                  --replace '@tarballHash_${system}@' $(nix --experimental-features nix-command hash-file --base16 --type sha256 ${tarball}/*.tar.xz) \
+                  --replace '@tarballPath_${system}@' $(tarballPath ${tarball}/*.tar.xz) \
+                  ''
+                )
+                systems
+              } --replace '@nixVersion@' ${version}
+
+            echo "file installer $out/install" >> $out/nix-support/hydra-build-products
+          '';
+
+      testNixVersions = pkgs: client: daemon: with commonDeps pkgs; with pkgs.lib; pkgs.stdenv.mkDerivation {
+        NIX_DAEMON_PACKAGE = daemon;
+        NIX_CLIENT_PACKAGE = client;
+        name =
+          "nix-tests"
+          + optionalString
+            (versionAtLeast daemon.version "2.4pre20211005" &&
+             versionAtLeast client.version "2.4pre20211005")
+            "-${client.version}-against-${daemon.version}";
+        inherit version;
+
+        src = self;
+
+        VERSION_SUFFIX = versionSuffix;
+
+        nativeBuildInputs = nativeBuildDeps;
+        buildInputs = buildDeps ++ awsDeps;
+        propagatedBuildInputs = propagatedDeps;
+
+        enableParallelBuilding = true;
+
+        dontBuild = true;
+        doInstallCheck = true;
+
+        installPhase = ''
+          mkdir -p $out
+        '';
+
+        installCheckPhase = "make installcheck -j$NIX_BUILD_CORES -l$NIX_BUILD_CORES";
+      };
+
+      binaryTarball = buildPackages: nix: pkgs: let
+        inherit (pkgs) cacert;
+        installerClosureInfo = buildPackages.closureInfo { rootPaths = [ nix cacert ]; };
+      in
+
+      buildPackages.runCommand "nix-binary-tarball-${version}"
+        { #nativeBuildInputs = lib.optional (system != "aarch64-linux") shellcheck;
+          meta.description = "Distribution-independent Nix bootstrap binaries for ${pkgs.system}";
+        }
+        ''
+          cp ${installerClosureInfo}/registration $TMPDIR/reginfo
+          cp ${./scripts/create-darwin-volume.sh} $TMPDIR/create-darwin-volume.sh
+          substitute ${./scripts/install-nix-from-closure.sh} $TMPDIR/install \
+            --subst-var-by nix ${nix} \
+            --subst-var-by cacert ${cacert}
+
+          substitute ${./scripts/install-darwin-multi-user.sh} $TMPDIR/install-darwin-multi-user.sh \
+            --subst-var-by nix ${nix} \
+            --subst-var-by cacert ${cacert}
+          substitute ${./scripts/install-systemd-multi-user.sh} $TMPDIR/install-systemd-multi-user.sh \
+            --subst-var-by nix ${nix} \
+            --subst-var-by cacert ${cacert}
+          substitute ${./scripts/install-multi-user.sh} $TMPDIR/install-multi-user \
+            --subst-var-by nix ${nix} \
+            --subst-var-by cacert ${cacert}
+
+          if type -p shellcheck; then
+            # SC1090: Don't worry about not being able to find
+            #         $nix/etc/profile.d/nix.sh
+            shellcheck --exclude SC1090 $TMPDIR/install
+            shellcheck $TMPDIR/create-darwin-volume.sh
+            shellcheck $TMPDIR/install-darwin-multi-user.sh
+            shellcheck $TMPDIR/install-systemd-multi-user.sh
+
+            # SC1091: Don't panic about not being able to source
+            #         /etc/profile
+            # SC2002: Ignore "useless cat" "error", when loading
+            #         .reginfo, as the cat is a much cleaner
+            #         implementation, even though it is "useless"
+            # SC2116: Allow ROOT_HOME=$(echo ~root) for resolving
+            #         root's home directory
+            shellcheck --external-sources \
+              --exclude SC1091,SC2002,SC2116 $TMPDIR/install-multi-user
+          fi
+
+          chmod +x $TMPDIR/install
+          chmod +x $TMPDIR/create-darwin-volume.sh
+          chmod +x $TMPDIR/install-darwin-multi-user.sh
+          chmod +x $TMPDIR/install-systemd-multi-user.sh
+          chmod +x $TMPDIR/install-multi-user
+          dir=nix-${version}-${pkgs.system}
+          fn=$out/$dir.tar.xz
+          mkdir -p $out/nix-support
+          echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
+          tar cvfJ $fn \
+            --owner=0 --group=0 --mode=u+rw,uga+r \
+            --absolute-names \
+            --hard-dereference \
+            --transform "s,$TMPDIR/install,$dir/install," \
+            --transform "s,$TMPDIR/create-darwin-volume.sh,$dir/create-darwin-volume.sh," \
+            --transform "s,$TMPDIR/reginfo,$dir/.reginfo," \
+            --transform "s,$NIX_STORE,$dir/store,S" \
+            $TMPDIR/install \
+            $TMPDIR/create-darwin-volume.sh \
+            $TMPDIR/install-darwin-multi-user.sh \
+            $TMPDIR/install-systemd-multi-user.sh \
+            $TMPDIR/install-multi-user \
+            $TMPDIR/reginfo \
+            $(cat ${installerClosureInfo}/store-paths)
+        '';
+
     in {
 
       # A Nixpkgs overlay that overrides the 'nix' and
       # 'nix.perl-bindings' packages.
       overlay = final: prev: {
 
+        nixStable = prev.nix;
+
+        # Forward from the previous stage as we don’t want it to pick the lowdown override
+        nixUnstable = prev.nixUnstable;
+
         nix = with final; with commonDeps pkgs; stdenv.mkDerivation {
           name = "nix-${version}";
           inherit version;
@@ -164,6 +314,8 @@
 
           separateDebugInfo = true;
 
+          strictDeps = true;
+
           passthru.perl-bindings = with final; stdenv.mkDerivation {
             name = "nix-perl-${version}";
 
@@ -182,9 +334,9 @@
                 xz
                 pkgs.perl
                 boost
-                nlohmann_json
               ]
-              ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium;
+              ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium
+              ++ lib.optional stdenv.isDarwin darwin.apple_sdk.frameworks.Security;
 
             configureFlags = ''
               --with-dbi=${perlPackages.DBI}/${pkgs.perl.libPrefix}
@@ -198,22 +350,17 @@
 
         };
 
-        lowdown = with final; stdenv.mkDerivation rec {
-          name = "lowdown-0.8.0";
+        lowdown-nix = with final; stdenv.mkDerivation rec {
+          name = "lowdown-0.9.0";
 
-          src = fetchurl {
-            url = "https://kristaps.bsd.lv/lowdown/snapshots/${name}.tar.gz";
-            hash = "sha512-U9WeGoInT9vrawwa57t6u9dEdRge4/P+0wLxmQyOL9nhzOEUU2FRz2Be9H0dCjYE7p2v3vCXIYk40M+jjULATw==";
-          };
-
-          #src = lowdown-src;
+          src = lowdown-src;
 
           outputs = [ "out" "bin" "dev" ];
 
-          nativeBuildInputs = [ which ];
+          nativeBuildInputs = [ buildPackages.which ];
 
-          configurePhase =
-            ''
+          configurePhase = ''
+              ${if (stdenv.isDarwin && stdenv.isAarch64) then "echo \"HAVE_SANDBOX_INIT=false\" > configure.local" else ""}
               ./configure \
                 PREFIX=${placeholder "dev"} \
                 BINDIR=${placeholder "bin"}/bin
@@ -229,124 +376,33 @@
 
         buildStatic = nixpkgs.lib.genAttrs linux64BitSystems (system: self.packages.${system}.nix-static);
 
+        buildCross = nixpkgs.lib.genAttrs crossSystems (crossSystem:
+          nixpkgs.lib.genAttrs ["x86_64-linux"] (system: self.packages.${system}."nix-${crossSystem}"));
+
         # Perl bindings for various platforms.
         perlBindings = nixpkgs.lib.genAttrs systems (system: self.packages.${system}.nix.perl-bindings);
 
         # Binary tarball for various platforms, containing a Nix store
         # with the closure of 'nix' package, and the second half of
         # the installation script.
-        binaryTarball = nixpkgs.lib.genAttrs systems (system:
+        binaryTarball = nixpkgs.lib.genAttrs systems (system: binaryTarball nixpkgsFor.${system} nixpkgsFor.${system}.nix nixpkgsFor.${system});
 
-          with nixpkgsFor.${system};
-
-          let
-            installerClosureInfo = closureInfo { rootPaths = [ nix cacert ]; };
-          in
-
-          runCommand "nix-binary-tarball-${version}"
-            { #nativeBuildInputs = lib.optional (system != "aarch64-linux") shellcheck;
-              meta.description = "Distribution-independent Nix bootstrap binaries for ${system}";
-            }
-            ''
-              cp ${installerClosureInfo}/registration $TMPDIR/reginfo
-              cp ${./scripts/create-darwin-volume.sh} $TMPDIR/create-darwin-volume.sh
-              substitute ${./scripts/install-nix-from-closure.sh} $TMPDIR/install \
-                --subst-var-by nix ${nix} \
-                --subst-var-by cacert ${cacert}
-
-              substitute ${./scripts/install-darwin-multi-user.sh} $TMPDIR/install-darwin-multi-user.sh \
-                --subst-var-by nix ${nix} \
-                --subst-var-by cacert ${cacert}
-              substitute ${./scripts/install-systemd-multi-user.sh} $TMPDIR/install-systemd-multi-user.sh \
-                --subst-var-by nix ${nix} \
-                --subst-var-by cacert ${cacert}
-              substitute ${./scripts/install-multi-user.sh} $TMPDIR/install-multi-user \
-                --subst-var-by nix ${nix} \
-                --subst-var-by cacert ${cacert}
-
-              if type -p shellcheck; then
-                # SC1090: Don't worry about not being able to find
-                #         $nix/etc/profile.d/nix.sh
-                shellcheck --exclude SC1090 $TMPDIR/install
-                shellcheck $TMPDIR/create-darwin-volume.sh
-                shellcheck $TMPDIR/install-darwin-multi-user.sh
-                shellcheck $TMPDIR/install-systemd-multi-user.sh
-
-                # SC1091: Don't panic about not being able to source
-                #         /etc/profile
-                # SC2002: Ignore "useless cat" "error", when loading
-                #         .reginfo, as the cat is a much cleaner
-                #         implementation, even though it is "useless"
-                # SC2116: Allow ROOT_HOME=$(echo ~root) for resolving
-                #         root's home directory
-                shellcheck --external-sources \
-                  --exclude SC1091,SC2002,SC2116 $TMPDIR/install-multi-user
-              fi
-
-              chmod +x $TMPDIR/install
-              chmod +x $TMPDIR/create-darwin-volume.sh
-              chmod +x $TMPDIR/install-darwin-multi-user.sh
-              chmod +x $TMPDIR/install-systemd-multi-user.sh
-              chmod +x $TMPDIR/install-multi-user
-              dir=nix-${version}-${system}
-              fn=$out/$dir.tar.xz
-              mkdir -p $out/nix-support
-              echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
-              tar cvfJ $fn \
-                --owner=0 --group=0 --mode=u+rw,uga+r \
-                --absolute-names \
-                --hard-dereference \
-                --transform "s,$TMPDIR/install,$dir/install," \
-                --transform "s,$TMPDIR/create-darwin-volume.sh,$dir/create-darwin-volume.sh," \
-                --transform "s,$TMPDIR/reginfo,$dir/.reginfo," \
-                --transform "s,$NIX_STORE,$dir/store,S" \
-                $TMPDIR/install \
-                $TMPDIR/create-darwin-volume.sh \
-                $TMPDIR/install-darwin-multi-user.sh \
-                $TMPDIR/install-systemd-multi-user.sh \
-                $TMPDIR/install-multi-user \
-                $TMPDIR/reginfo \
-                $(cat ${installerClosureInfo}/store-paths)
-            '');
+        binaryTarballCross = nixpkgs.lib.genAttrs ["x86_64-linux"] (system: builtins.listToAttrs (map (crossSystem: {
+          name = crossSystem;
+          value = let
+            nixpkgsCross = import nixpkgs {
+              inherit system crossSystem;
+              overlays = [ self.overlay ];
+            };
+          in binaryTarball nixpkgsFor.${system} self.packages.${system}."nix-${crossSystem}" nixpkgsCross;
+        }) crossSystems));
 
         # The first half of the installation script. This is uploaded
         # to https://nixos.org/nix/install. It downloads the binary
         # tarball for the user's system and calls the second half of the
         # installation script.
-        installerScript =
-          with nixpkgsFor.x86_64-linux;
-          runCommand "installer-script"
-            { buildInputs = [ nix ];
-            }
-            ''
-              mkdir -p $out/nix-support
-
-              # Converts /nix/store/50p3qk8kka9dl6wyq40vydq945k0j3kv-nix-2.4pre20201102_550e11f/bin/nix
-              # To 50p3qk8kka9dl6wyq40vydq945k0j3kv/bin/nix
-              tarballPath() {
-                # Remove the store prefix
-                local path=''${1#${builtins.storeDir}/}
-                # Get the path relative to the derivation root
-                local rest=''${path#*/}
-                # Get the derivation hash
-                local drvHash=''${path%%-*}
-                echo "$drvHash/$rest"
-              }
-
-              substitute ${./scripts/install.in} $out/install \
-                ${pkgs.lib.concatMapStrings
-                  (system:
-                    '' \
-                    --replace '@tarballHash_${system}@' $(nix --experimental-features nix-command hash-file --base16 --type sha256 ${self.hydraJobs.binaryTarball.${system}}/*.tar.xz) \
-                    --replace '@tarballPath_${system}@' $(tarballPath ${self.hydraJobs.binaryTarball.${system}}/*.tar.xz) \
-                    ''
-                  )
-                  [ "x86_64-linux" "i686-linux" "x86_64-darwin" "aarch64-linux" ]
-                } \
-                --replace '@nixVersion@' ${version}
-
-              echo "file installer $out/install" >> $out/nix-support/hydra-build-products
-            '';
+        installerScript = installScriptFor [ "x86_64-linux" "i686-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" "armv6l-linux" "armv7l-linux" ];
+        installerScriptForGHA = installScriptFor [ "x86_64-linux" "x86_64-darwin" "armv6l-linux" "armv7l-linux"];
 
         # Line coverage analysis.
         coverage =
@@ -431,11 +487,24 @@
       checks = forAllSystems (system: {
         binaryTarball = self.hydraJobs.binaryTarball.${system};
         perlBindings = self.hydraJobs.perlBindings.${system};
+        installTests =
+          let pkgs = nixpkgsFor.${system}; in
+          pkgs.runCommand "install-tests" {
+            againstSelf = testNixVersions pkgs pkgs.nix pkgs.pkgs.nix;
+            againstCurrentUnstable =
+              # FIXME: temporarily disable this on macOS because of #3605.
+              if system == "x86_64-linux"
+              then testNixVersions pkgs pkgs.nix pkgs.nixUnstable
+              else null;
+            # Disabled because the latest stable version doesn't handle
+            # `NIX_DAEMON_SOCKET_PATH` which is required for the tests to work
+            # againstLatestStable = testNixVersions pkgs pkgs.nix pkgs.nixStable;
+          } "touch $out";
       });
 
       packages = forAllSystems (system: {
         inherit (nixpkgsFor.${system}) nix;
-      } // nixpkgs.lib.optionalAttrs (builtins.elem system linux64BitSystems) {
+      } // (nixpkgs.lib.optionalAttrs (builtins.elem system linux64BitSystems) {
         nix-static = let
           nixpkgs = nixpkgsFor.${system}.pkgsStatic;
         in with commonDeps nixpkgs; nixpkgs.stdenv.mkDerivation {
@@ -471,8 +540,51 @@
           installCheckFlags = "sysconfdir=$(out)/etc";
 
           stripAllList = ["bin"];
+
+          strictDeps = true;
+
+          hardeningDisable = [ "pie" ];
         };
-      });
+      } // builtins.listToAttrs (map (crossSystem: {
+        name = "nix-${crossSystem}";
+        value = let
+          nixpkgsCross = import nixpkgs {
+            inherit system crossSystem;
+            overlays = [ self.overlay ];
+          };
+        in with commonDeps nixpkgsCross; nixpkgsCross.stdenv.mkDerivation {
+          name = "nix-${version}";
+
+          src = self;
+
+          VERSION_SUFFIX = versionSuffix;
+
+          outputs = [ "out" "dev" "doc" ];
+
+          nativeBuildInputs = nativeBuildDeps;
+          buildInputs = buildDeps ++ propagatedDeps;
+
+          configureFlags = [ "--sysconfdir=/etc" "--disable-doc-gen" ];
+
+          enableParallelBuilding = true;
+
+          makeFlags = "profiledir=$(out)/etc/profile.d";
+
+          doCheck = true;
+
+          installFlags = "sysconfdir=$(out)/etc";
+
+          postInstall = ''
+            mkdir -p $doc/nix-support
+            echo "doc manual $doc/share/doc/nix/manual" >> $doc/nix-support/hydra-build-products
+            mkdir -p $out/nix-support
+            echo "file binary-dist $out/bin/nix" >> $out/nix-support/hydra-build-products
+          '';
+
+          doInstallCheck = true;
+          installCheckFlags = "sysconfdir=$(out)/etc";
+        };
+      }) crossSystems)));
 
       defaultPackage = forAllSystems (system: self.packages.${system}.nix);
 

maintainers/upload-release.pl

@@ -83,12 +83,12 @@ sub downloadFile {
 
     if (!-e $tmpFile) {
         print STDERR "downloading $srcFile to $tmpFile...\n";
-        system("NIX_REMOTE=https://cache.nixos.org/ nix cat-store '$srcFile' > '$tmpFile'") == 0
+        system("NIX_REMOTE=https://cache.nixos.org/ nix store cat '$srcFile' > '$tmpFile'") == 0
             or die "unable to fetch $srcFile\n";
     }
 
     my $sha256_expected = $buildInfo->{buildproducts}->{$productNr}->{sha256hash} or die;
-    my $sha256_actual = `nix hash-file --base16 --type sha256 '$tmpFile'`;
+    my $sha256_actual = `nix hash file --base16 --type sha256 '$tmpFile'`;
     chomp $sha256_actual;
     if ($sha256_expected ne $sha256_actual) {
         print STDERR "file $tmpFile is corrupt, got $sha256_actual, expected $sha256_expected\n";
@@ -110,6 +110,9 @@ downloadFile("binaryTarball.i686-linux", "1");
 downloadFile("binaryTarball.x86_64-linux", "1");
 downloadFile("binaryTarball.aarch64-linux", "1");
 downloadFile("binaryTarball.x86_64-darwin", "1");
+downloadFile("binaryTarball.aarch64-darwin", "1");
+downloadFile("binaryTarballCross.x86_64-linux.armv6l-linux", "1");
+downloadFile("binaryTarballCross.x86_64-linux.armv7l-linux", "1");
 downloadFile("installerScript", "1");
 
 for my $fn (glob "$tmpDir/*") {
@@ -133,20 +136,8 @@ for my $fn (glob "$tmpDir/*") {
 
 exit if $version =~ /pre/;
 
-# Update Nixpkgs in a very hacky way.
+# Update nix-fallback-paths.nix.
 system("cd $nixpkgsDir && git pull") == 0 or die;
-my $oldName = `nix-instantiate --eval $nixpkgsDir -A nix.name`; chomp $oldName;
-my $oldHash = `nix-instantiate --eval $nixpkgsDir -A nix.src.outputHash`; chomp $oldHash;
-print STDERR "old stable version in Nixpkgs = $oldName / $oldHash\n";
-
-my $fn = "$nixpkgsDir/pkgs/tools/package-management/nix/default.nix";
-my $oldFile = read_file($fn);
-$oldFile =~ s/$oldName/"$releaseName"/g;
-$oldFile =~ s/$oldHash/"$tarballHash"/g;
-write_file($fn, $oldFile);
-
-$oldName =~ s/nix-//g;
-$oldName =~ s/"//g;
 
 sub getStorePath {
     my ($jobName) = @_;
@@ -165,9 +156,10 @@ write_file("$nixpkgsDir/nixos/modules/installer/tools/nix-fallback-paths.nix",
            "  i686-linux = \"" . getStorePath("build.i686-linux") . "\";\n" .
            "  aarch64-linux = \"" . getStorePath("build.aarch64-linux") . "\";\n" .
            "  x86_64-darwin = \"" . getStorePath("build.x86_64-darwin") . "\";\n" .
+           "  aarch64-darwin = \"" . getStorePath("build.aarch64-darwin") . "\";\n" .
            "}\n");
 
-system("cd $nixpkgsDir && git commit -a -m 'nix: $oldName -> $version'") == 0 or die;
+system("cd $nixpkgsDir && git commit -a -m 'nix-fallback-paths.nix: Update to $version'") == 0 or die;
 
 # Update the "latest" symlink.
 $channelsBucket->add_key(

misc/fish/completion.fish

@@ -0,0 +1,37 @@
+function _nix_complete
+  # Get the current command up to a cursor.
+  # - Behaves correctly even with pipes and nested in commands like env.
+  # - TODO: Returns the command verbatim (does not interpolate variables).
+  #   That might not be optimal for arguments like -f.
+  set -l nix_args (commandline --current-process --tokenize --cut-at-cursor)
+  # --cut-at-cursor with --tokenize removes the current token so we need to add it separately.
+  # https://github.com/fish-shell/fish-shell/issues/7375
+  # Can be an empty string.
+  set -l current_token (commandline --current-token --cut-at-cursor)
+
+  # Nix wants the index of the argv item to complete but the $nix_args variable
+  # also contains the program name (argv[0]) so we would need to subtract 1.
+  # But the variable also misses the current token so it cancels out.
+  set -l nix_arg_to_complete (count $nix_args)
+
+  env NIX_GET_COMPLETIONS=$nix_arg_to_complete $nix_args $current_token
+end
+
+function _nix_accepts_files
+  set -l response (_nix_complete)
+  # First line is either filenames or no-filenames.
+  test $response[1] = 'filenames'
+end
+
+function _nix
+  set -l response (_nix_complete)
+  # Skip the first line since it handled by _nix_accepts_files.
+  # Tail lines each contain a command followed by a tab character and, optionally, a description.
+  # This is also the format fish expects.
+  string collect -- $response[2..-1]
+end
+
+# Disable file path completion if paths do not belong in the current context.
+complete --command nix --condition 'not _nix_accepts_files' --no-files
+
+complete --command nix --arguments '(_nix)'

misc/fish/local.mk

@@ -0,0 +1 @@
+$(eval $(call install-file-as, $(d)/completion.fish, $(datarootdir)/fish/vendor_completions.d/nix.fish, 0644))

misc/launchd/local.mk

@@ -1,4 +1,4 @@
-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
 
   $(eval $(call install-data-in, $(d)/org.nixos.nix-daemon.plist, $(prefix)/Library/LaunchDaemons))
 

misc/launchd/org.nixos.nix-daemon.plist.in

@@ -19,7 +19,7 @@
     <array>
       <string>/bin/sh</string>
       <string>-c</string>
-      <string>/bin/wait4path /nix/var/nix/profiles/default/bin/nix-daemon &amp;&amp; /nix/var/nix/profiles/default/bin/nix-daemon</string>
+      <string>/bin/wait4path /nix/var/nix/profiles/default/bin/nix-daemon &amp;&amp; exec /nix/var/nix/profiles/default/bin/nix-daemon</string>
     </array>
     <key>StandardErrorPath</key>
     <string>/var/log/nix-daemon.log</string>

misc/systemd/local.mk

@@ -1,4 +1,4 @@
-ifeq ($(OS), Linux)
+ifdef HOST_LINUX
 
   $(foreach n, nix-daemon.socket nix-daemon.service, $(eval $(call install-file-in, $(d)/$(n), $(prefix)/lib/systemd/system, 0644)))
 

misc/upstart/local.mk

@@ -1,4 +1,4 @@
-ifeq ($(OS), Linux)
+ifdef HOST_LINUX
 
   $(foreach n, nix-daemon.conf, $(eval $(call install-file-in, $(d)/$(n), $(sysconfdir)/init, 0644)))
 

misc/zsh/completion.zsh

@@ -1,3 +1,5 @@
+#compdef nix
+
 function _nix() {
   local ifs_bk="$IFS"
   local input=("${(Q)words[@]}")
@@ -18,4 +20,4 @@ function _nix() {
   _describe 'nix' suggestions
 }
 
-compdef _nix nix
+_nix "$@"

misc/zsh/local.mk

@@ -0,0 +1 @@
+$(eval $(call install-file-as, $(d)/completion.zsh, $(datarootdir)/zsh/site-functions/_nix, 0644))

mk/jars.mk

@@ -1,36 +0,0 @@
-define build-jar
-
-  $(1)_NAME ?= $(1)
-
-  _d := $$(strip $$($(1)_DIR))
-
-  $(1)_PATH := $$(_d)/$$($(1)_NAME).jar
-
-  $(1)_TMPDIR := $$(_d)/.$$($(1)_NAME).jar.tmp
-
-  _jars := $$(foreach jar, $$($(1)_JARS), $$($$(jar)_PATH))
-
-  $$($(1)_PATH): $$($(1)_SOURCES) $$(_jars) $$($(1)_EXTRA_DEPS)| $$($(1)_ORDER_AFTER)
-	@rm -rf $$($(1)_TMPDIR)
-	@mkdir -p $$($(1)_TMPDIR)
-	$$(trace-javac) javac $(GLOBAL_JAVACFLAGS) $$($(1)_JAVACFLAGS) -d $$($(1)_TMPDIR) \
-	  $$(foreach fn, $$($(1)_SOURCES), '$$(fn)') \
-	  -cp "$$(subst $$(space),,$$(foreach jar,$$($(1)_JARS),$$($$(jar)_PATH):))$$$$CLASSPATH"
-	@echo -e '$$(subst $$(newline),\n,$$($(1)_MANIFEST))' > $$($(1)_PATH).manifest
-	$$(trace-jar) jar cfm $$($(1)_PATH) $$($(1)_PATH).manifest -C $$($(1)_TMPDIR) .
-	@rm $$($(1)_PATH).manifest
-	@rm -rf $$($(1)_TMPDIR)
-
-  $(1)_INSTALL_DIR ?= $$(jardir)
-
-  $(1)_INSTALL_PATH := $$($(1)_INSTALL_DIR)/$$($(1)_NAME).jar
-
-  $$(eval $$(call install-file-as, $$($(1)_PATH), $$($(1)_INSTALL_PATH), 0644))
-
-  install: $$($(1)_INSTALL_PATH)
-
-  jars-list += $$($(1)_PATH)
-
-  clean-files += $$($(1)_PATH)
-
-endef

mk/lib.mk

@@ -10,8 +10,25 @@ bin-scripts :=
 noinst-scripts :=
 man-pages :=
 install-tests :=
-OS = $(shell uname -s)
 
+ifdef HOST_OS
+  HOST_KERNEL = $(firstword $(subst -, ,$(HOST_OS)))
+  ifeq ($(HOST_KERNEL), cygwin)
+    HOST_CYGWIN = 1
+  endif
+  ifeq ($(patsubst darwin%,,$(HOST_KERNEL)),)
+    HOST_DARWIN = 1
+  endif
+  ifeq ($(patsubst freebsd%,,$(HOST_KERNEL)),)
+    HOST_FREEBSD = 1
+  endif
+  ifeq ($(HOST_KERNEL), linux)
+    HOST_LINUX = 1
+  endif
+  ifeq ($(patsubst solaris%,,$(HOST_KERNEL)),)
+    HOST_SOLARIS = 1
+  endif
+endif
 
 # Hack to define a literal space.
 space :=
@@ -31,7 +48,6 @@ libdir ?= $(prefix)/lib
 bindir ?= $(prefix)/bin
 libexecdir ?= $(prefix)/libexec
 datadir ?= $(prefix)/share
-jardir ?= $(datadir)/java
 localstatedir ?= $(prefix)/var
 sysconfdir ?= $(prefix)/etc
 mandir ?= $(prefix)/share/man
@@ -51,16 +67,16 @@ endif
 BUILD_SHARED_LIBS ?= 1
 
 ifeq ($(BUILD_SHARED_LIBS), 1)
-  ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+  ifdef HOST_CYGWIN
     GLOBAL_CFLAGS += -U__STRICT_ANSI__ -D_GNU_SOURCE
     GLOBAL_CXXFLAGS += -U__STRICT_ANSI__ -D_GNU_SOURCE
   else
     GLOBAL_CFLAGS += -fPIC
     GLOBAL_CXXFLAGS += -fPIC
   endif
-  ifneq ($(OS), Darwin)
-   ifneq ($(OS), SunOS)
-    ifneq ($(OS), FreeBSD)
+  ifndef HOST_DARWIN
+   ifndef HOST_SOLARIS
+    ifndef HOST_FREEBSD
      GLOBAL_LDFLAGS += -Wl,--no-copy-dt-needed-entries
     endif
    endif
@@ -74,7 +90,6 @@ BUILD_DEBUG ?= 1
 ifeq ($(BUILD_DEBUG), 1)
   GLOBAL_CFLAGS += -g
   GLOBAL_CXXFLAGS += -g
-  GLOBAL_JAVACFLAGS += -g
 endif
 
 
@@ -84,7 +99,6 @@ include mk/clean.mk
 include mk/install.mk
 include mk/libraries.mk
 include mk/programs.mk
-include mk/jars.mk
 include mk/patterns.mk
 include mk/templates.mk
 include mk/tests.mk
@@ -102,7 +116,6 @@ $(foreach mf, $(makefiles), $(eval $(call include-sub-makefile, $(mf))))
 # Instantiate stuff.
 $(foreach lib, $(libraries), $(eval $(call build-library,$(lib))))
 $(foreach prog, $(programs), $(eval $(call build-program,$(prog))))
-$(foreach jar, $(jars), $(eval $(call build-jar,$(jar))))
 $(foreach script, $(bin-scripts), $(eval $(call install-program-in,$(script),$(bindir))))
 $(foreach script, $(bin-scripts), $(eval programs-list += $(script)))
 $(foreach script, $(noinst-scripts), $(eval programs-list += $(script)))
@@ -113,7 +126,7 @@ $(foreach file, $(man-pages), $(eval $(call install-data-in, $(file), $(mandir)/
 
 .PHONY: default all man help
 
-all: $(programs-list) $(libs-list) $(jars-list) $(man-pages)
+all: $(programs-list) $(libs-list) $(man-pages)
 
 man: $(man-pages)
 
@@ -137,12 +150,6 @@ ifdef libs-list
 	@echo "The following libraries can be built:"
 	@echo ""
 	@for i in $(libs-list); do echo "  $$i"; done
-endif
-ifdef jars-list
-	@echo ""
-	@echo "The following JARs can be built:"
-	@echo ""
-	@for i in $(jars-list); do echo "  $$i"; done
 endif
 	@echo ""
 	@echo "The following variables control the build:"
@@ -153,4 +160,5 @@ endif
 	@echo "  CFLAGS: Flags for the C compiler"
 	@echo "  CXX ($(CXX)): C++ compiler to be used"
 	@echo "  CXXFLAGS: Flags for the C++ compiler"
+	@echo "  CPPFLAGS: C preprocessor flags, used for both CC and CXX"
 	@$(print-var-help)

mk/libraries.mk

@@ -1,9 +1,9 @@
 libs-list :=
 
-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
   SO_EXT = dylib
 else
-  ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+  ifdef HOST_CYGWIN
     SO_EXT = dll
   else
     SO_EXT = so
@@ -59,7 +59,7 @@ define build-library
   $(1)_OBJS := $$(addprefix $(buildprefix), $$(addsuffix .o, $$(basename $$(_srcs))))
   _libs := $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_PATH))
 
-  ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+  ifdef HOST_CYGWIN
     $(1)_INSTALL_DIR ?= $$(bindir)
   else
     $(1)_INSTALL_DIR ?= $$(libdir)
@@ -73,18 +73,18 @@ define build-library
   ifeq ($(BUILD_SHARED_LIBS), 1)
 
     ifdef $(1)_ALLOW_UNDEFINED
-      ifeq ($(OS), Darwin)
+      ifdef HOST_DARWIN
         $(1)_LDFLAGS += -undefined suppress -flat_namespace
       endif
     else
-      ifneq ($(OS), Darwin)
-        ifneq (CYGWIN,$(findstring CYGWIN,$(OS)))
+      ifndef HOST_DARWIN
+        ifndef HOST_CYGWIN
           $(1)_LDFLAGS += -Wl,-z,defs
         endif
       endif
     endif
 
-    ifneq ($(OS), Darwin)
+    ifndef HOST_DARWIN
       $(1)_LDFLAGS += -Wl,-soname=$$($(1)_NAME).$(SO_EXT)
     endif
 
@@ -93,7 +93,7 @@ define build-library
     $$($(1)_PATH): $$($(1)_OBJS) $$(_libs) | $$(_d)/
 	$$(trace-ld) $(CXX) -o $$(abspath $$@) -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$($(1)_LDFLAGS_UNINSTALLED)
 
-    ifneq ($(OS), Darwin)
+    ifndef HOST_DARWIN
       $(1)_LDFLAGS_USE += -Wl,-rpath,$$(abspath $$(_d))
     endif
     $(1)_LDFLAGS_USE += -L$$(_d) -l$$(patsubst lib%,%,$$(strip $$($(1)_NAME)))
@@ -108,7 +108,7 @@ define build-library
 	$$(trace-ld) $(CXX) -o $$@ -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED))
 
     $(1)_LDFLAGS_USE_INSTALLED += -L$$(DESTDIR)$$($(1)_INSTALL_DIR) -l$$(patsubst lib%,%,$$(strip $$($(1)_NAME)))
-    ifneq ($(OS), Darwin)
+    ifndef HOST_DARWIN
       ifeq ($(SET_RPATH_TO_LIBS), 1)
         $(1)_LDFLAGS_USE_INSTALLED += -Wl,-rpath,$$($(1)_INSTALL_DIR)
       else
@@ -125,8 +125,8 @@ define build-library
     $(1)_PATH := $$(_d)/$$($(1)_NAME).a
 
     $$($(1)_PATH): $$($(1)_OBJS) | $$(_d)/
-	$(trace-ld) $(LD) -Ur -o $$(_d)/$$($(1)_NAME).o $$?
-	$(trace-ar) $(AR) crs $$@ $$(_d)/$$($(1)_NAME).o
+	$$(trace-ld) $(LD) -Ur -o $$(_d)/$$($(1)_NAME).o $$?
+	$$(trace-ar) $(AR) crs $$@ $$(_d)/$$($(1)_NAME).o
 
     $(1)_LDFLAGS_USE += $$($(1)_PATH) $$($(1)_LDFLAGS)
 

mk/patterns.mk

@@ -1,11 +1,11 @@
 $(buildprefix)%.o: %.cc
 	@mkdir -p "$(dir $@)"
-	$(trace-cxx) $(CXX) -o $@ -c $< $(GLOBAL_CXXFLAGS_PCH) $(GLOBAL_CXXFLAGS) $(CXXFLAGS) $($@_CXXFLAGS) -MMD -MF $(call filename-to-dep, $@) -MP
+	$(trace-cxx) $(CXX) -o $@ -c $< $(CPPFLAGS) $(GLOBAL_CXXFLAGS_PCH) $(GLOBAL_CXXFLAGS) $(CXXFLAGS) $($@_CXXFLAGS) -MMD -MF $(call filename-to-dep, $@) -MP
 
 $(buildprefix)%.o: %.cpp
 	@mkdir -p "$(dir $@)"
-	$(trace-cxx) $(CXX) -o $@ -c $< $(GLOBAL_CXXFLAGS_PCH) $(GLOBAL_CXXFLAGS) $(CXXFLAGS) $($@_CXXFLAGS) -MMD -MF $(call filename-to-dep, $@) -MP
+	$(trace-cxx) $(CXX) -o $@ -c $< $(CPPFLAGS) $(GLOBAL_CXXFLAGS_PCH) $(GLOBAL_CXXFLAGS) $(CXXFLAGS) $($@_CXXFLAGS) -MMD -MF $(call filename-to-dep, $@) -MP
 
 $(buildprefix)%.o: %.c
 	@mkdir -p "$(dir $@)"
-	$(trace-cc) $(CC) -o $@ -c $< $(GLOBAL_CFLAGS) $(CFLAGS) $($@_CFLAGS) -MMD -MF $(call filename-to-dep, $@) -MP
+	$(trace-cc) $(CC) -o $@ -c $< $(CPPFLAGS) $(GLOBAL_CFLAGS) $(CFLAGS) $($@_CFLAGS) -MMD -MF $(call filename-to-dep, $@) -MP

mk/run_test.sh

@@ -14,7 +14,7 @@ if [ -t 1 ]; then
     yellow=""
     normal=""
 fi
-(cd $(dirname $1) && env ${TESTS_ENVIRONMENT} init.sh 2>/dev/null > /dev/null)
+(cd tests && env ${TESTS_ENVIRONMENT} init.sh 2>/dev/null > /dev/null)
 log="$(cd $(dirname $1) && env ${TESTS_ENVIRONMENT} $(basename $1) 2>&1)"
 status=$?
 if [ $status -eq 0 ]; then

mk/tests.mk

@@ -8,8 +8,12 @@ define run-install-test
 
   .PHONY: $1.test
   $1.test: $1 $(test-deps)
-	@env TEST_NAME=$(notdir $(basename $1)) TESTS_ENVIRONMENT="$(tests-environment)" mk/run_test.sh $1 < /dev/null
+	@env TEST_NAME=$(basename $1) TESTS_ENVIRONMENT="$(tests-environment)" mk/run_test.sh $1 < /dev/null
 
 endef
 
 .PHONY: check installcheck
+
+print-top-help += \
+  echo "  check: Run unit tests"; \
+  echo "  installcheck: Run functional tests";

mk/tracing.mk

@@ -8,8 +8,6 @@ ifeq ($(V), 0)
   trace-ld      = @echo "  LD    " $@;
   trace-ar      = @echo "  AR    " $@;
   trace-install = @echo "  INST  " $@;
-  trace-javac   = @echo "  JAVAC " $@;
-  trace-jar     = @echo "  JAR   " $@;
   trace-mkdir   = @echo "  MKDIR " $@;
   trace-test    = @echo "  TEST  " $@;
 

nix-rust/local.mk

@@ -8,10 +8,15 @@ endif
 
 libnixrust_PATH := $(d)/target/$(RUST_DIR)/libnixrust.$(SO_EXT)
 libnixrust_INSTALL_PATH := $(libdir)/libnixrust.$(SO_EXT)
-libnixrust_LDFLAGS_USE := -L$(d)/target/$(RUST_DIR) -lnixrust -ldl
-libnixrust_LDFLAGS_USE_INSTALLED := -L$(libdir) -lnixrust -ldl
+libnixrust_LDFLAGS_USE := -L$(d)/target/$(RUST_DIR) -lnixrust
+libnixrust_LDFLAGS_USE_INSTALLED := -L$(libdir) -lnixrust
 
-ifeq ($(OS), Darwin)
+ifdef HOST_LINUX
+libnixrust_LDFLAGS_USE += -ldl
+libnixrust_LDFLAGS_USE_INSTALLED += -ldl
+endif
+
+ifdef HOST_DARWIN
 libnixrust_BUILD_FLAGS = NIX_LDFLAGS="-undefined dynamic_lookup"
 else
 libnixrust_LDFLAGS_USE += -Wl,-rpath,$(abspath $(d)/target/$(RUST_DIR))
@@ -26,7 +31,7 @@ $(libnixrust_PATH): $(call rwildcard, $(d)/src, *.rs) $(d)/Cargo.toml
 
 $(libnixrust_INSTALL_PATH): $(libnixrust_PATH)
 	$(target-gen) cp $^ $@
-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
 	install_name_tool -id $@ $@
 endif
 
@@ -35,7 +40,7 @@ clean: clean-rust
 clean-rust:
 	$(suppress) rm -rfv nix-rust/target
 
-ifneq ($(OS), Darwin)
+ifndef HOST_DARWIN
 check: rust-tests
 
 rust-tests:

perl/Makefile

@@ -1,6 +1,6 @@
 makefiles = local.mk
 
-GLOBAL_CXXFLAGS += -g -Wall -std=c++17
+GLOBAL_CXXFLAGS += -g -Wall -std=c++17 -I ../src
 
 -include Makefile.config
 

perl/Makefile.config.in

@@ -1,3 +1,4 @@
+HOST_OS = @host_os@
 CC = @CC@
 CFLAGS = @CFLAGS@
 CXX = @CXX@

perl/configure.ac

@@ -7,6 +7,8 @@ CXXFLAGS=
 AC_PROG_CC
 AC_PROG_CXX
 
+AC_CANONICAL_HOST
+
 # Use 64-bit file system calls so that we can support files > 2 GiB.
 AC_SYS_LARGEFILE
 

perl/lib/Nix/Store.pm

@@ -22,6 +22,7 @@ our @EXPORT = qw(
     derivationFromPath
     addTempRoot
     getBinDir getStoreDir
+    queryRawRealisation
 );
 
 our $VERSION = '0.15';

perl/lib/Nix/Store.xs

@@ -15,6 +15,7 @@
 #include "crypto.hh"
 
 #include <sodium.h>
+#include <nlohmann/json.hpp>
 
 
 using namespace nix;
@@ -120,6 +121,18 @@ SV * queryPathInfo(char * path, int base32)
             croak("%s", e.what());
         }
 
+SV * queryRawRealisation(char * outputId)
+    PPCODE:
+      try {
+        auto realisation = store()->queryRealisation(DrvOutput::parse(outputId));
+        if (realisation)
+            XPUSHs(sv_2mortal(newSVpv(realisation->toJSON().dump().c_str(), 0)));
+        else
+            XPUSHs(sv_2mortal(newSVpv("", 0)));
+      } catch (Error & e) {
+        croak("%s", e.what());
+      }
+
 
 SV * queryPathFromHashPart(char * hashPart)
     PPCODE:

perl/local.mk

@@ -28,7 +28,7 @@ Store_CXXFLAGS = \
 
 Store_LDFLAGS := $(SODIUM_LIBS) $(NIX_LIBS)
 
-ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+ifdef HOST_CYGWIN
   archlib = $(shell perl -E 'use Config; print $$Config{archlib};')
   libperl = $(shell perl -E 'use Config; print $$Config{libperl};')
   Store_LDFLAGS += $(shell find ${archlib} -name ${libperl})

scripts/bigsur-nixbld-user-migration.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+
+((NEW_NIX_FIRST_BUILD_UID=301))
+
+id_available(){
+	dscl . list /Users UniqueID | grep -E '\b'$1'\b' >/dev/null
+}
+
+change_nixbld_names_and_ids(){
+	local name uid next_id
+	((next_id=NEW_NIX_FIRST_BUILD_UID))
+	echo "Attempting to migrate nixbld users."
+	echo "Each user should change from nixbld# to _nixbld#"
+	echo "and their IDs relocated to $next_id+"
+	while read -r name uid; do
+		echo "   Checking $name (uid: $uid)"
+		# iterate for a clean ID
+		while id_available "$next_id"; do
+			((next_id++))
+			if ((next_id >= 400)); then
+				echo "We've hit UID 400 without placing all of your users :("
+				echo "You should use the commands in this script as a starting"
+				echo "point to review your UID-space and manually move the"
+				echo "remaining users (or delete them, if you don't need them)."
+				exit 1
+			fi
+		done
+
+		if [[ $name == _* ]]; then
+			echo "      It looks like $name has already been renamed--skipping."
+		else
+			# first 3 are cleanup, it's OK if they aren't here
+			sudo dscl . delete /Users/$name dsAttrTypeNative:_writers_passwd &>/dev/null || true
+			sudo dscl . change /Users/$name NFSHomeDirectory "/private/var/empty 1" "/var/empty" &>/dev/null || true
+			# remove existing user from group
+			sudo dseditgroup -o edit -t user -d $name nixbld || true
+			sudo dscl . change /Users/$name UniqueID $uid $next_id
+			sudo dscl . change /Users/$name RecordName $name _$name
+			# add renamed user to group
+			sudo dseditgroup -o edit -t user -a _$name nixbld
+			echo "      $name migrated to _$name (uid: $next_id)"
+		fi
+	done < <(dscl . list /Users UniqueID | grep nixbld | sort -n -k2)
+}
+
+change_nixbld_names_and_ids

scripts/create-darwin-volume.sh

@@ -1,33 +1,262 @@
-#!/bin/sh
-set -e
+#!/usr/bin/env bash
+set -eu
+set -o pipefail
 
-root_disk() {
-    diskutil info -plist /
-}
+# I'm a little agnostic on the choices, but supporting a wide
+# slate of uses for now, including:
+# - import-only: `. create-darwin-volume.sh no-main[ ...]`
+# - legacy: `./create-darwin-volume.sh` or `. create-darwin-volume.sh`
+#   (both will run main())
+# - external alt-routine: `./create-darwin-volume.sh no-main func[ ...]`
+if [ "${1-}" = "no-main" ]; then
+    shift
+    readonly _CREATE_VOLUME_NO_MAIN=1
+else
+    readonly _CREATE_VOLUME_NO_MAIN=0
+    # declare some things we expect to inherit from install-multi-user
+    # I don't love this (because it's a bit of a kludge).
+    #
+    # CAUTION: (Dec 19 2020)
+    # This is a stopgap. It doesn't cover the full slate of
+    # identifiers we inherit--just those necessary to:
+    # - avoid breaking direct invocations of this script (here/now)
+    # - avoid hard-to-reverse structural changes before the call to rm
+    #   single-user support is verified
+    #
+    # In the near-mid term, I (personally) think we should:
+    # - decide to deprecate the direct call and add a notice
+    # - fold all of this into install-darwin-multi-user.sh
+    # - intentionally remove the old direct-invocation form (kill the
+    #   routine, replace this script w/ deprecation notice and a note
+    #   on the remove-after date)
+    #
+    readonly NIX_ROOT="${NIX_ROOT:-/nix}"
 
-# i.e., "disk1"
+    _sudo() {
+        shift # throw away the 'explanation'
+        /usr/bin/sudo "$@"
+    }
+    failure() {
+        if [ "$*" = "" ]; then
+            cat
+        else
+            echo "$@"
+        fi
+        exit 1
+    }
+    task() {
+        echo "$@"
+    }
+fi
+
+# usually "disk1"
 root_disk_identifier() {
-    diskutil info -plist / | xmllint --xpath "/plist/dict/key[text()='ParentWholeDisk']/following-sibling::string[1]/text()" -
+    # For performance (~10ms vs 280ms) I'm parsing 'diskX' from stat output
+    # (~diskXsY)--but I'm retaining the more-semantic approach since
+    # it documents intent better.
+    # /usr/sbin/diskutil info -plist / | xmllint --xpath "/plist/dict/key[text()='ParentWholeDisk']/following-sibling::string[1]/text()" -
+    #
+    local special_device
+    special_device="$(/usr/bin/stat -f "%Sd" /)"
+    echo "${special_device%s[0-9]*}"
 }
 
-find_nix_volume() {
-    diskutil apfs list -plist "$1" | xmllint --xpath "(/plist/dict/array/dict/key[text()='Volumes']/following-sibling::array/dict/key[text()='Name']/following-sibling::string[starts-with(translate(text(),'N','n'),'nix')]/text())[1]" - 2>/dev/null || true
+# make it easy to play w/ 'Case-sensitive APFS'
+readonly NIX_VOLUME_FS="${NIX_VOLUME_FS:-APFS}"
+readonly NIX_VOLUME_LABEL="${NIX_VOLUME_LABEL:-Nix Store}"
+# Strongly assuming we'll make a volume on the device / is on
+# But you can override NIX_VOLUME_USE_DISK to create it on some other device
+readonly NIX_VOLUME_USE_DISK="${NIX_VOLUME_USE_DISK:-$(root_disk_identifier)}"
+NIX_VOLUME_USE_SPECIAL="${NIX_VOLUME_USE_SPECIAL:-}"
+NIX_VOLUME_USE_UUID="${NIX_VOLUME_USE_UUID:-}"
+readonly NIX_VOLUME_MOUNTD_DEST="${NIX_VOLUME_MOUNTD_DEST:-/Library/LaunchDaemons/org.nixos.darwin-store.plist}"
+
+if /usr/bin/fdesetup isactive >/dev/null; then
+    test_filevault_in_use() { return 0; }
+    # no readonly; we may modify if user refuses from cure_volume
+    NIX_VOLUME_DO_ENCRYPT="${NIX_VOLUME_DO_ENCRYPT:-1}"
+else
+    test_filevault_in_use() { return 1; }
+    NIX_VOLUME_DO_ENCRYPT="${NIX_VOLUME_DO_ENCRYPT:-0}"
+fi
+
+should_encrypt_volume() {
+    test_filevault_in_use && (( NIX_VOLUME_DO_ENCRYPT == 1 ))
+}
+
+substep() {
+    printf "   %s\n" "" "- $1" "" "${@:2}"
+}
+
+
+volumes_labeled() {
+    local label="$1"
+    xsltproc --novalid --stringparam label "$label" - <(/usr/sbin/ioreg -ra -c "AppleAPFSVolume") <<'EOF'
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+  <xsl:output method="text"/>
+  <xsl:template match="/">
+    <xsl:apply-templates select="/plist/array/dict/key[text()='IORegistryEntryName']/following-sibling::*[1][text()=$label]/.."/>
+  </xsl:template>
+  <xsl:template match="dict">
+    <xsl:apply-templates match="string" select="key[text()='BSD Name']/following-sibling::*[1]"/>
+    <xsl:text>=</xsl:text>
+    <xsl:apply-templates match="string" select="key[text()='UUID']/following-sibling::*[1]"/>
+    <xsl:text>&#xA;</xsl:text>
+  </xsl:template>
+</xsl:stylesheet>
+EOF
+    # I cut label out of the extracted values, but here it is for reference:
+    # <xsl:apply-templates match="string" select="key[text()='IORegistryEntryName']/following-sibling::*[1]"/>
+    # <xsl:text>=</xsl:text>
+}
+
+right_disk() {
+    local volume_special="$1" # (i.e., disk1s7)
+    [[ "$volume_special" == "$NIX_VOLUME_USE_DISK"s* ]]
+}
+
+right_volume() {
+    local volume_special="$1" # (i.e., disk1s7)
+    # if set, it must match; otherwise ensure it's on the right disk
+    if [ -z "$NIX_VOLUME_USE_SPECIAL" ]; then
+        if right_disk "$volume_special"; then
+            NIX_VOLUME_USE_SPECIAL="$volume_special" # latch on
+            return 0
+        else
+            return 1
+        fi
+    else
+        [ "$volume_special" = "$NIX_VOLUME_USE_SPECIAL" ]
+    fi
+}
+
+right_uuid() {
+    local volume_uuid="$1"
+    # if set, it must match; otherwise allow
+    if [ -z "$NIX_VOLUME_USE_UUID" ]; then
+        NIX_VOLUME_USE_UUID="$volume_uuid" # latch on
+        return 0
+    else
+        [ "$volume_uuid" = "$NIX_VOLUME_USE_UUID" ]
+    fi
+}
+
+cure_volumes() {
+    local found volume special uuid
+    # loop just in case they have more than one volume
+    # (nothing stops you from doing this)
+    for volume in $(volumes_labeled "$NIX_VOLUME_LABEL"); do
+        # CAUTION: this could (maybe) be a more normal read
+        # loop like:
+        #   while IFS== read -r special uuid; do
+        #       # ...
+        #   done <<<"$(volumes_labeled "$NIX_VOLUME_LABEL")"
+        #
+        # I did it with for to skirt a problem with the obvious
+        # pattern replacing stdin and causing user prompts
+        # inside (which also use read and access stdin) to skip
+        #
+        # If there's an existing encrypted volume we can't find
+        # in keychain, the user never gets prompted to delete
+        # the volume, and the install fails.
+        #
+        # If you change this, a human needs to test a very
+        # specific scenario: you already have an encrypted
+        # Nix Store volume, and have deleted its credential
+        # from keychain. Ensure the script asks you if it can
+        # delete the volume, and then prompts for your sudo
+        # password to confirm.
+        #
+        # shellcheck disable=SC1097
+        IFS== read -r special uuid <<< "$volume"
+        # take the first one that's on the right disk
+        if [ -z "${found:-}" ]; then
+            if right_volume "$special" && right_uuid "$uuid"; then
+                cure_volume "$special" "$uuid"
+                found="${special} (${uuid})"
+            else
+                warning <<EOF
+Ignoring ${special} (${uuid}) because I am looking for:
+disk=${NIX_VOLUME_USE_DISK} special=${NIX_VOLUME_USE_SPECIAL:-${NIX_VOLUME_USE_DISK}sX} uuid=${NIX_VOLUME_USE_UUID:-any}
+EOF
+                # TODO: give chance to delete if ! headless?
+            fi
+        else
+            warning <<EOF
+Ignoring ${special} (${uuid}), already found target: $found
+EOF
+            # TODO reminder? I feel like I want one
+            # idiom that reminds some warnings, or warns
+            # some reminders?
+            # TODO: if ! headless, chance to delete?
+        fi
+    done
+    if [ -z "${found:-}" ]; then
+        readonly NIX_VOLUME_USE_SPECIAL NIX_VOLUME_USE_UUID
+    fi
+}
+
+volume_encrypted() {
+    local volume_special="$1" # (i.e., disk1s7)
+    # Trying to match the first line of output; known first lines:
+    # No cryptographic users for <special>
+    # Cryptographic user for <special> (1 found)
+    # Cryptographic users for <special> (2 found)
+    /usr/sbin/diskutil apfs listCryptoUsers -plist "$volume_special" | /usr/bin/grep -q APFSCryptoUserUUID
 }
 
 test_fstab() {
-    grep -q "/nix apfs rw" /etc/fstab 2>/dev/null
+    /usr/bin/grep -q "$NIX_ROOT apfs rw" /etc/fstab 2>/dev/null
 }
 
-test_nix_symlink() {
-    [ -L "/nix" ] || grep -q "^nix." /etc/synthetic.conf 2>/dev/null
+test_nix_root_is_symlink() {
+    [ -L "$NIX_ROOT" ]
 }
 
-test_synthetic_conf() {
-    grep -q "^nix$" /etc/synthetic.conf 2>/dev/null
+test_synthetic_conf_either(){
+    /usr/bin/grep -qE "^${NIX_ROOT:1}($|\t.{3,}$)" /etc/synthetic.conf 2>/dev/null
+}
+
+test_synthetic_conf_mountable() {
+    /usr/bin/grep -q "^${NIX_ROOT:1}$" /etc/synthetic.conf 2>/dev/null
+}
+
+test_synthetic_conf_symlinked() {
+    /usr/bin/grep -qE "^${NIX_ROOT:1}\t.{3,}$" /etc/synthetic.conf 2>/dev/null
+}
+
+test_nix_volume_mountd_installed() {
+    test -e "$NIX_VOLUME_MOUNTD_DEST"
+}
+
+# current volume password
+test_keychain_by_uuid() {
+    local volume_uuid="$1"
+    # Note: doesn't need sudo just to check; doesn't output pw
+    security find-generic-password -s "$volume_uuid" &>/dev/null
+}
+
+get_volume_pass() {
+    local volume_uuid="$1"
+    _sudo \
+        "to confirm keychain has a password that unlocks this volume" \
+        security find-generic-password -s "$volume_uuid" -w
+}
+
+verify_volume_pass() {
+    local volume_special="$1" # (i.e., disk1s7)
+    local volume_uuid="$2"
+    /usr/sbin/diskutil apfs unlockVolume "$volume_special" -verify -stdinpassphrase -user "$volume_uuid"
+}
+
+volume_pass_works() {
+    local volume_special="$1" # (i.e., disk1s7)
+    local volume_uuid="$2"
+    get_volume_pass "$volume_uuid" | verify_volume_pass "$volume_special" "$volume_uuid"
 }
 
 # Create the paths defined in synthetic.conf, saving us a reboot.
-create_synthetic_objects(){
+create_synthetic_objects() {
     # Big Sur takes away the -B flag we were using and replaces it
     # with a -t flag that appears to do the same thing (but they
     # don't behave exactly the same way in terms of return values).
@@ -41,129 +270,575 @@ create_synthetic_objects(){
 }
 
 test_nix() {
-    test -d "/nix"
+    test -d "$NIX_ROOT"
 }
 
-test_t2_chip_present(){
-    # Use xartutil to see if system has a t2 chip.
-    #
-    # This isn't well-documented on its own; until it is,
-    # let's keep track of knowledge/assumptions.
-    #
-    # Warnings:
-    # - Don't search "xart" if porn will cause you trouble :)
-    # - Other xartutil flags do dangerous things. Don't run them
-    #   naively. If you must, search "xartutil" first.
-    #
-    # Assumptions:
-    # - the "xART session seeds recovery utility"
-    #   appears to interact with xartstorageremoted
-    # - `sudo xartutil --list` lists xART sessions
-    #   and their seeds and exits 0 if successful. If
-    #   not, it exits 1 and prints an error such as:
-    #   xartutil: ERROR: No supported link to the SEP present
-    # - xART sessions/seeds are present when a T2 chip is
-    #   (and not, otherwise)
-    # - the presence of a T2 chip means a newly-created
-    #   volume on the primary drive will be
-    #   encrypted at rest
-    # - all together: `sudo xartutil --list`
-    #   should exit 0 if a new Nix Store volume will
-    #   be encrypted at rest, and exit 1 if not.
-    sudo xartutil --list >/dev/null 2>/dev/null
+test_voldaemon() {
+    test -f "$NIX_VOLUME_MOUNTD_DEST"
 }
 
-test_filevault_in_use() {
-    fdesetup isactive >/dev/null
+generate_mount_command() {
+    local cmd_type="$1" # encrypted|unencrypted
+    local volume_uuid mountpoint cmd=()
+    printf -v volume_uuid "%q" "$2"
+    printf -v mountpoint "%q" "$NIX_ROOT"
+
+    case "$cmd_type" in
+        encrypted)
+            cmd=(/bin/sh -c "/usr/bin/security find-generic-password -s '$volume_uuid' -w | /usr/sbin/diskutil apfs unlockVolume '$volume_uuid' -mountpoint '$mountpoint' -stdinpassphrase");;
+        unencrypted)
+            cmd=(/usr/sbin/diskutil mount -mountPoint "$mountpoint" "$volume_uuid");;
+        *)
+            failure "Invalid first arg $cmd_type to generate_mount_command";;
+    esac
+
+    printf "    <string>%s</string>\n" "${cmd[@]}"
 }
 
-# use after error msg for conditions we don't understand
-suggest_report_error(){
-    # ex "error: something sad happened :(" >&2
-    echo "       please report this @ https://github.com/nixos/nix/issues" >&2
+generate_mount_daemon() {
+    local cmd_type="$1" # encrypted|unencrypted
+    local volume_uuid="$2"
+    cat <<EOF
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+  <key>RunAtLoad</key>
+  <true/>
+  <key>Label</key>
+  <string>org.nixos.darwin-store</string>
+  <key>ProgramArguments</key>
+  <array>
+$(generate_mount_command "$cmd_type" "$volume_uuid")
+  </array>
+</dict>
+</plist>
+EOF
 }
 
-main() {
-    (
-        echo ""
-        echo "     ------------------------------------------------------------------ "
-        echo "    | This installer will create a volume for the nix store and        |"
-        echo "    | configure it to mount at /nix.  Follow these steps to uninstall. |"
-        echo "     ------------------------------------------------------------------ "
-        echo ""
-        echo "  1. Remove the entry from fstab using 'sudo vifs'"
-        echo "  2. Destroy the data volume using 'diskutil apfs deleteVolume'"
-        echo "  3. Remove the 'nix' line from /etc/synthetic.conf or the file"
-        echo ""
-    ) >&2
+_eat_bootout_err() {
+    /usr/bin/grep -v "Boot-out failed: 36: Operation now in progress"
+}
 
-    if test_nix_symlink; then
-        echo "error: /nix is a symlink, please remove it and make sure it's not in synthetic.conf (in which case a reboot is required)" >&2
-        echo "  /nix -> $(readlink "/nix")" >&2
-        exit 2
+# TODO: remove with --uninstall?
+uninstall_launch_daemon_directions() {
+    local daemon_label="$1" # i.e., org.nixos.blah-blah
+    local daemon_plist="$2" # abspath
+    substep "Uninstall LaunchDaemon $daemon_label" \
+      "  sudo launchctl bootout system/$daemon_label" \
+      "  sudo rm $daemon_plist"
+}
+
+uninstall_launch_daemon_prompt() {
+    local daemon_label="$1" # i.e., org.nixos.blah-blah
+    local daemon_plist="$2" # abspath
+    local reason_for_daemon="$3"
+    cat <<EOF
+
+The installer adds a LaunchDaemon to $reason_for_daemon: $daemon_label
+EOF
+    if ui_confirm "Can I remove it?"; then
+        _sudo "to terminate the daemon" \
+            launchctl bootout "system/$daemon_label" 2> >(_eat_bootout_err >&2) || true
+            # this can "fail" with a message like:
+            # Boot-out failed: 36: Operation now in progress
+        _sudo "to remove the daemon definition" rm "$daemon_plist"
+    fi
+}
+
+nix_volume_mountd_uninstall_directions() {
+    uninstall_launch_daemon_directions "org.nixos.darwin-store" \
+        "$NIX_VOLUME_MOUNTD_DEST"
+}
+
+nix_volume_mountd_uninstall_prompt() {
+    uninstall_launch_daemon_prompt "org.nixos.darwin-store" \
+        "$NIX_VOLUME_MOUNTD_DEST" \
+        "mount your Nix volume"
+}
+
+# TODO: move nix_daemon to install-darwin-multi-user if/when uninstall_launch_daemon_prompt moves up to install-multi-user
+nix_daemon_uninstall_prompt() {
+    uninstall_launch_daemon_prompt "org.nixos.nix-daemon" \
+        "$NIX_DAEMON_DEST" \
+        "run the nix-daemon"
+}
+
+# TODO: remove with --uninstall?
+nix_daemon_uninstall_directions() {
+    uninstall_launch_daemon_directions "org.nixos.nix-daemon" \
+        "$NIX_DAEMON_DEST"
+}
+
+
+# TODO: remove with --uninstall?
+synthetic_conf_uninstall_directions() {
+    # :1 to strip leading slash
+    substep "Remove ${NIX_ROOT:1} from /etc/synthetic.conf" \
+        "  If nix is the only entry: sudo rm /etc/synthetic.conf" \
+        "  Otherwise: sudo /usr/bin/sed -i '' -e '/^${NIX_ROOT:1}$/d' /etc/synthetic.conf"
+}
+
+synthetic_conf_uninstall_prompt() {
+    cat <<EOF
+
+During install, I add '${NIX_ROOT:1}' to /etc/synthetic.conf, which instructs
+macOS to create an empty root directory for mounting the Nix volume.
+EOF
+    # make the edit to a copy
+    /usr/bin/grep -vE "^${NIX_ROOT:1}($|\t.{3,}$)" /etc/synthetic.conf > "$SCRATCH/synthetic.conf.edit"
+
+    if test_synthetic_conf_symlinked; then
+        warning <<EOF
+
+/etc/synthetic.conf already contains a line instructing your system
+to make '${NIX_ROOT}' as a symlink:
+    $(/usr/bin/grep -nE "^${NIX_ROOT:1}\t.{3,}$" /etc/synthetic.conf)
+
+This may mean your system has/had a non-standard Nix install.
+
+The volume-creation process in this installer is *not* compatible
+with a symlinked store, so I'll have to remove this instruction to
+continue.
+
+If you want/need to keep this instruction, answer 'n' to abort.
+
+EOF
     fi
 
-    if ! test_synthetic_conf; then
-        echo "Configuring /etc/synthetic.conf..." >&2
-        echo nix | sudo tee -a /etc/synthetic.conf
-        if ! test_synthetic_conf; then
-            echo "error: failed to configure synthetic.conf;" >&2
-            suggest_report_error
-            exit 1
+    # ask to rm if this left the file empty aside from comments, else edit
+    if /usr/bin/diff -q <(:) <(/usr/bin/grep -v "^#" "$SCRATCH/synthetic.conf.edit") &>/dev/null; then
+        if confirm_rm "/etc/synthetic.conf"; then
+            if test_nix_root_is_symlink; then
+                failure >&2 <<EOF
+I removed /etc/synthetic.conf, but $NIX_ROOT is already a symlink
+(-> $(readlink "$NIX_ROOT")). The system should remove it when you reboot.
+Once you've rebooted, run the installer again.
+EOF
+            fi
+            return 0
+        fi
+    else
+        if confirm_edit "$SCRATCH/synthetic.conf.edit" "/etc/synthetic.conf"; then
+            if test_nix_root_is_symlink; then
+                failure >&2 <<EOF
+I edited Nix out of /etc/synthetic.conf, but $NIX_ROOT is already a symlink
+(-> $(readlink "$NIX_ROOT")). The system should remove it when you reboot.
+Once you've rebooted, run the installer again.
+EOF
+            fi
+            return 0
         fi
     fi
+    # fallback instructions
+    echo "Manually remove nix from /etc/synthetic.conf"
+    return 1
+}
 
-    if ! test_nix; then
-        echo "Creating mountpoint for /nix..." >&2
-        create_synthetic_objects # the ones we defined in synthetic.conf
-        if ! test_nix; then
-            sudo mkdir -p /nix 2>/dev/null || true
+add_nix_vol_fstab_line() {
+    local uuid="$1"
+    # shellcheck disable=SC1003,SC2026
+    local escaped_mountpoint="${NIX_ROOT/ /'\\\'040}"
+    shift
+    EDITOR="/usr/bin/ex" _sudo "to add nix to fstab" "$@" <<EOF
+:a
+UUID=$uuid $escaped_mountpoint apfs rw,noauto,nobrowse,suid,owners
+.
+:x
+EOF
+    # TODO: preserving my notes on suid,owners above until resolved
+    # There *may* be some issue regarding volume ownership, see nix#3156
+    #
+    # It seems like the cheapest fix is adding "suid,owners" to fstab, but:
+    # - We don't have much info on this condition yet
+    # - I'm not certain if these cause other problems?
+    # - There's a "chown" component some people claim to need to fix this
+    #   that I don't understand yet
+    #   (Note however that I've had to add a chown step to handle
+    #   single->multi-user reinstalls, which may cover this)
+    #
+    # I'm not sure if it's safe to approach this way?
+    #
+    # I think I think the most-proper way to test for it is:
+    # diskutil info -plist "$NIX_VOLUME_LABEL" | xmllint --xpath "(/plist/dict/key[text()='GlobalPermissionsEnabled'])/following-sibling::*[1][name()='true']" -; echo $?
+    #
+    # There's also `sudo /usr/sbin/vsdbutil -c /path` (which is much faster, but is also
+    # deprecated and needs minor parsing).
+    #
+    # If no one finds a problem with doing so, I think the simplest approach
+    # is to just eagerly set this. I found a few imperative approaches:
+    # (diskutil enableOwnership, ~100ms), a cheap one (/usr/sbin/vsdbutil -a, ~40-50ms),
+    # a very cheap one (append the internal format to /var/db/volinfo.database).
+    #
+    # But vsdbutil's deprecation notice suggests using fstab, so I want to
+    # give that a whirl first.
+    #
+    # TODO: when this is workable, poke infinisil about reproducing the issue
+    # and confirming this fix?
+}
+
+delete_nix_vol_fstab_line() {
+    # TODO: I'm scaffolding this to handle the new nix volumes
+    # but it might be nice to generalize a smidge further to
+    # go ahead and set up a pattern for curing "old" things
+    # we no longer do?
+    EDITOR="/usr/bin/patch" _sudo "to cut nix from fstab" "$@" < <(/usr/bin/diff /etc/fstab <(/usr/bin/grep -v "$NIX_ROOT apfs rw" /etc/fstab))
+    # leaving some parts out of the grep; people may fiddle this a little?
+}
+
+# TODO: hope to remove with --uninstall
+fstab_uninstall_directions() {
+    substep "Remove ${NIX_ROOT} from /etc/fstab" \
+      "  If nix is the only entry: sudo rm /etc/fstab" \
+      "  Otherwise, run 'sudo /usr/sbin/vifs' to remove the nix line"
+}
+
+fstab_uninstall_prompt() {
+    cat <<EOF
+During install, I add '${NIX_ROOT}' to /etc/fstab so that macOS knows what
+mount options to use for the Nix volume.
+EOF
+    cp /etc/fstab "$SCRATCH/fstab.edit"
+    # technically doesn't need the _sudo path, but throwing away the
+    # output is probably better than mostly-duplicating the code...
+    delete_nix_vol_fstab_line patch "$SCRATCH/fstab.edit" &>/dev/null
+
+    # if the patch test edit, minus comment lines, is equal to empty (:)
+    if /usr/bin/diff -q <(:) <(/usr/bin/grep -v "^#" "$SCRATCH/fstab.edit") &>/dev/null; then
+        # this edit would leave it empty; propose deleting it
+        if confirm_rm "/etc/fstab"; then
+            return 0
+        else
+            echo "Remove nix from /etc/fstab (or remove the file)"
         fi
-        if ! test_nix; then
-            echo "error: failed to bootstrap /nix; if a reboot doesn't help," >&2
-            suggest_report_error
-            exit 1
+    else
+        echo "I might be able to help you make this edit. Here's the diff:"
+        if ! _diff "/etc/fstab" "$SCRATCH/fstab.edit" && ui_confirm "Does the change above look right?"; then
+            delete_nix_vol_fstab_line /usr/sbin/vifs
+        else
+            echo "Remove nix from /etc/fstab (or remove the file)"
         fi
     fi
+}
 
-    disk="$(root_disk_identifier)"
-    volume=$(find_nix_volume "$disk")
-    if [ -z "$volume" ]; then
-        echo "Creating a Nix Store volume..." >&2
+remove_volume() {
+    local volume_special="$1" # (i.e., disk1s7)
+    _sudo "to unmount the Nix volume" \
+        /usr/sbin/diskutil unmount force "$volume_special" || true # might not be mounted
+    _sudo "to delete the Nix volume" \
+        /usr/sbin/diskutil apfs deleteVolume "$volume_special"
+}
 
-        if test_filevault_in_use; then
-            # TODO: Not sure if it's in-scope now, but `diskutil apfs list`
-            # shows both filevault and encrypted at rest status, and it
-            # may be the more semantic way to test for this? It'll show
-            # `FileVault:                 No (Encrypted at rest)`
-            # `FileVault:                 No`
-            # `FileVault:                 Yes (Unlocked)`
-            # and so on.
-            if test_t2_chip_present; then
-                echo "warning: boot volume is FileVault-encrypted, but the Nix store volume" >&2
-                echo "         is only encrypted at rest." >&2
-                echo "         See https://nixos.org/nix/manual/#sect-macos-installation" >&2
+# aspiration: robust enough to both fix problems
+# *and* update older darwin volumes
+cure_volume() {
+    local volume_special="$1" # (i.e., disk1s7)
+    local volume_uuid="$2"
+    header "Found existing Nix volume"
+    row "  special" "$volume_special"
+    row "     uuid" "$volume_uuid"
+
+    if volume_encrypted "$volume_special"; then
+        row "encrypted" "yes"
+        if volume_pass_works "$volume_special" "$volume_uuid"; then
+            NIX_VOLUME_DO_ENCRYPT=0
+            ok "Found a working decryption password in keychain :)"
+            echo ""
+        else
+            # - this is a volume we made, and
+            #   - the user encrypted it on their own
+            #   - something deleted the credential
+            # - this is an old or BYO volume and the pw
+            #   just isn't somewhere we can find it.
+            #
+            # We're going to explain why we're freaking out
+            # and prompt them to either delete the volume
+            # (requiring a sudo auth), or abort to fix
+            warning <<EOF
+
+This volume is encrypted, but I don't see a password to decrypt it.
+The quick fix is to let me delete this volume and make you a new one.
+If that's okay, enter your (sudo) password to continue. If not, you
+can ensure the decryption password is in your system keychain with a
+"Where" (service) field set to this volume's UUID:
+  $volume_uuid
+EOF
+            if password_confirm "delete this volume"; then
+                remove_volume "$volume_special"
             else
-                echo "error: refusing to create Nix store volume because the boot volume is" >&2
-                echo "       FileVault encrypted, but encryption-at-rest is not available." >&2
-                echo "       Manually create a volume for the store and re-run this script." >&2
-                echo "       See https://nixos.org/nix/manual/#sect-macos-installation" >&2
-                exit 1
+                # TODO: this is a good design case for a warn-and
+                # remind idiom...
+                failure <<EOF
+Your Nix volume is encrypted, but I couldn't find its password. Either:
+- Delete or rename the volume out of the way
+- Ensure its decryption password is in the system keychain with a
+  "Where" (service) field set to this volume's UUID:
+    $volume_uuid
+EOF
+            fi
+        fi
+    elif test_filevault_in_use; then
+        row "encrypted" "no"
+        warning <<EOF
+FileVault is on, but your $NIX_VOLUME_LABEL volume isn't encrypted.
+EOF
+        # if we're interactive, give them a chance to
+        # encrypt the volume. If not, /shrug
+        if ! headless && (( NIX_VOLUME_DO_ENCRYPT == 1 )); then
+            if ui_confirm "Should I encrypt it and add the decryption key to your keychain?"; then
+                encrypt_volume "$volume_uuid" "$NIX_VOLUME_LABEL"
+                NIX_VOLUME_DO_ENCRYPT=0
+            else
+                NIX_VOLUME_DO_ENCRYPT=0
+                reminder "FileVault is on, but your $NIX_VOLUME_LABEL volume isn't encrypted."
             fi
         fi
-
-        sudo diskutil apfs addVolume "$disk" APFS 'Nix Store' -mountpoint /nix
-        volume="Nix Store"
     else
-        echo "Using existing '$volume' volume" >&2
-    fi
-
-    if ! test_fstab; then
-        echo "Configuring /etc/fstab..." >&2
-        label=$(echo "$volume" | sed 's/ /\\040/g')
-        # shellcheck disable=SC2209
-        printf "\$a\nLABEL=%s /nix apfs rw,nobrowse\n.\nwq\n" "$label" | EDITOR=ed sudo vifs
+        row "encrypted" "no"
     fi
 }
 
-main "$@"
+remove_volume_artifacts() {
+    if test_synthetic_conf_either; then
+        # NIX_ROOT is in synthetic.conf
+        if synthetic_conf_uninstall_prompt; then
+            # TODO: moot until we tackle uninstall, but when we're
+            # actually uninstalling, we should issue:
+            # reminder "macOS will clean up the empty mount-point directory at $NIX_ROOT on reboot."
+            :
+        fi
+    fi
+    if test_fstab; then
+        fstab_uninstall_prompt
+    fi
+
+    if test_nix_volume_mountd_installed; then
+        nix_volume_mountd_uninstall_prompt
+    fi
+}
+
+setup_synthetic_conf() {
+    if test_nix_root_is_symlink; then
+        if ! test_synthetic_conf_symlinked; then
+            failure >&2 <<EOF
+error: $NIX_ROOT is a symlink (-> $(readlink "$NIX_ROOT")).
+Please remove it. If nix is in /etc/synthetic.conf, remove it and reboot.
+EOF
+        fi
+    fi
+    if ! test_synthetic_conf_mountable; then
+        task "Configuring /etc/synthetic.conf to make a mount-point at $NIX_ROOT" >&2
+        # technically /etc/synthetic.d/nix is supported in Big Sur+
+        # but handling both takes even more code...
+        _sudo "to add Nix to /etc/synthetic.conf" \
+            /usr/bin/ex /etc/synthetic.conf <<EOF
+:a
+${NIX_ROOT:1}
+.
+:x
+EOF
+        if ! test_synthetic_conf_mountable; then
+            failure "error: failed to configure synthetic.conf" >&2
+        fi
+        create_synthetic_objects
+        if ! test_nix; then
+            failure >&2 <<EOF
+error: failed to bootstrap $NIX_ROOT
+If you enabled FileVault after booting, this is likely a known issue
+with macOS that you'll have to reboot to fix. If you didn't enable FV,
+though, please open an issue describing how the system that you see
+this error on was set up.
+EOF
+        fi
+    fi
+}
+
+setup_fstab() {
+    local volume_uuid="$1"
+    # fstab used to be responsible for mounting the volume. Now the last
+    # step adds a LaunchDaemon responsible for mounting. This is technically
+    # redundant for mounting, but diskutil appears to pick up mount options
+    # from fstab (and diskutil's support for specifying them directly is not
+    # consistent across versions/subcommands).
+    if ! test_fstab; then
+        task "Configuring /etc/fstab to specify volume mount options" >&2
+        add_nix_vol_fstab_line "$volume_uuid" /usr/sbin/vifs
+    fi
+}
+
+encrypt_volume() {
+    local volume_uuid="$1"
+    local volume_label="$2"
+    local password
+    # Note: mount/unmount are late additions to support the right order
+    # of operations for creating the volume and then baking its uuid into
+    # other artifacts; not as well-trod wrt to potential errors, race
+    # conditions, etc.
+
+    /usr/sbin/diskutil mount "$volume_label"
+
+    password="$(/usr/bin/xxd -l 32 -p -c 256 /dev/random)"
+    _sudo "to add your Nix volume's password to Keychain" \
+        /usr/bin/security -i <<EOF
+add-generic-password -a "$volume_label" -s "$volume_uuid" -l "$volume_label encryption password" -D "Encrypted volume password" -j "Added automatically by the Nix installer for use by $NIX_VOLUME_MOUNTD_DEST" -w "$password" -T /System/Library/CoreServices/APFSUserAgent -T /System/Library/CoreServices/CSUserAgent -T /usr/bin/security "/Library/Keychains/System.keychain"
+EOF
+    builtin printf "%s" "$password" | _sudo "to encrypt your Nix volume" \
+        /usr/sbin/diskutil apfs encryptVolume "$volume_label" -user disk -stdinpassphrase
+
+    /usr/sbin/diskutil unmount force "$volume_label"
+}
+
+create_volume() {
+    # Notes:
+    # 1) using `-nomount` instead of `-mountpoint "$NIX_ROOT"` to get
+    # its UUID and set mount opts in fstab before first mount
+    #
+    # 2) system is in some sense less secure than user keychain... (it's
+    # possible to read the password for decrypting the keychain) but
+    # the user keychain appears to be available too late. As far as I
+    # can tell, the file with this password (/var/db/SystemKey) is
+    # inside the FileVault envelope. If that isn't true, it may make
+    # sense to store the password inside the envelope?
+    #
+    # 3) At some point it would be ideal to have a small binary to serve
+    # as the daemon itself, and for it to replace /usr/bin/security here.
+    #
+    # 4) *UserAgent exemptions should let the system seamlessly supply the
+    # password if noauto is removed from fstab entry. This is intentional;
+    # the user will hopefully look for help if the volume stops mounting,
+    # rather than failing over into subtle race-condition problems.
+    #
+    # 5) If we ever get users griping about not having space to do
+    # anything useful with Nix, it is possibly to specify
+    # `-reserve 10g` or something, which will fail w/o that much
+    #
+    # 6) getting special w/ awk may be fragile, but doing it to:
+    #    - save time over running slow diskutil commands
+    #    - skirt risk we grab wrong volume if multiple match
+    _sudo "to create a new APFS volume '$NIX_VOLUME_LABEL' on $NIX_VOLUME_USE_DISK" \
+        /usr/sbin/diskutil apfs addVolume "$NIX_VOLUME_USE_DISK" "$NIX_VOLUME_FS" "$NIX_VOLUME_LABEL" -nomount | /usr/bin/awk '/Created new APFS Volume/ {print $5}'
+}
+
+volume_uuid_from_special() {
+    local volume_special="$1" # (i.e., disk1s7)
+    # For reasons I won't pretend to fathom, this returns 253 when it works
+    /System/Library/Filesystems/apfs.fs/Contents/Resources/apfs.util -k "$volume_special" || true
+}
+
+# this sometimes clears immediately, and AFAIK clears
+# within about 1s. diskutil info on an unmounted path
+# fails in around 50-100ms and a match takes about
+# 250-300ms. I suspect it's usually ~250-750ms
+await_volume() {
+    # caution: this could, in theory, get stuck
+    until /usr/sbin/diskutil info "$NIX_ROOT" &>/dev/null; do
+        :
+    done
+}
+
+setup_volume() {
+    local use_special use_uuid profile_packages
+    task "Creating a Nix volume" >&2
+
+    use_special="${NIX_VOLUME_USE_SPECIAL:-$(create_volume)}"
+
+    use_uuid=${NIX_VOLUME_USE_UUID:-$(volume_uuid_from_special "$use_special")}
+
+    setup_fstab "$use_uuid"
+
+    if should_encrypt_volume; then
+        encrypt_volume "$use_uuid" "$NIX_VOLUME_LABEL"
+        setup_volume_daemon "encrypted" "$use_uuid"
+    # TODO: might be able to save ~60ms by caching or setting
+    # this somewhere rather than re-checking here.
+    elif volume_encrypted "$use_special"; then
+        setup_volume_daemon "encrypted" "$use_uuid"
+    else
+        setup_volume_daemon "unencrypted" "$use_uuid"
+    fi
+
+    await_volume
+
+    if [ "$(/usr/sbin/diskutil info -plist "$NIX_ROOT" | xmllint --xpath "(/plist/dict/key[text()='GlobalPermissionsEnabled'])/following-sibling::*[1]" -)" = "<false/>" ]; then
+        _sudo "to set enableOwnership (enabling users to own files)" \
+            /usr/sbin/diskutil enableOwnership "$NIX_ROOT"
+    fi
+
+    # TODO: below is a vague kludge for now; I just don't know
+    # what if any safe action there is to take here. Also, the
+    # reminder isn't very helpful.
+    # I'm less sure where this belongs, but it also wants mounted, pre-install
+    if type -p nix-env; then
+        profile_packages="$(nix-env --query --installed)"
+        # TODO: can probably do below faster w/ read
+        # intentionally unquoted string to eat whitespace in wc output
+        # shellcheck disable=SC2046,SC2059
+        if ! [ $(printf "$profile_packages" | /usr/bin/wc -l) = "0" ]; then
+            reminder <<EOF
+Nix now supports only multi-user installs on Darwin/macOS, and your user's
+Nix profile has some packages in it. These packages may obscure those in the
+default profile, including the Nix this installer will add. You should
+review these packages:
+$profile_packages
+EOF
+        fi
+    fi
+
+}
+
+setup_volume_daemon() {
+    local cmd_type="$1" # encrypted|unencrypted
+    local volume_uuid="$2"
+    if ! test_voldaemon; then
+        task "Configuring LaunchDaemon to mount '$NIX_VOLUME_LABEL'" >&2
+        _sudo "to install the Nix volume mounter" /usr/bin/ex "$NIX_VOLUME_MOUNTD_DEST" <<EOF
+:a
+$(generate_mount_daemon "$cmd_type" "$volume_uuid")
+.
+:x
+EOF
+
+        # TODO: should probably alert the user if this is disabled?
+        _sudo "to launch the Nix volume mounter" \
+            launchctl bootstrap system "$NIX_VOLUME_MOUNTD_DEST" || true
+        # TODO: confirm whether kickstart is necessesary?
+        # I feel a little superstitous, but it can guard
+        # against multiple problems (doesn't start, old
+        # version still running for some reason...)
+        _sudo "to launch the Nix volume mounter" \
+            launchctl kickstart -k system/org.nixos.darwin-store
+    fi
+}
+
+setup_darwin_volume() {
+    setup_synthetic_conf
+    setup_volume
+}
+
+if [ "$_CREATE_VOLUME_NO_MAIN" = 1 ]; then
+    if [ -n "$*" ]; then
+        "$@" # expose functions in case we want multiple routines?
+    fi
+else
+    # no reason to pay for bash to process this
+    main() {
+        {
+            echo ""
+            echo "     ------------------------------------------------------------------ "
+            echo "    | This installer will create a volume for the nix store and        |"
+            echo "    | configure it to mount at $NIX_ROOT.  Follow these steps to uninstall. |"
+            echo "     ------------------------------------------------------------------ "
+            echo ""
+            echo "  1. Remove the entry from fstab using 'sudo /usr/sbin/vifs'"
+            echo "  2. Run 'sudo launchctl bootout system/org.nixos.darwin-store'"
+            echo "  3. Remove $NIX_VOLUME_MOUNTD_DEST"
+            echo "  4. Destroy the data volume using '/usr/sbin/diskutil apfs deleteVolume'"
+            echo "  5. Remove the 'nix' line from /etc/synthetic.conf (or the file)"
+            echo ""
+        } >&2
+
+        setup_darwin_volume
+    }
+
+    main "$@"
+fi

scripts/install-darwin-multi-user.sh

@@ -3,57 +3,110 @@
 set -eu
 set -o pipefail
 
-readonly PLIST_DEST=/Library/LaunchDaemons/org.nixos.nix-daemon.plist
+readonly NIX_DAEMON_DEST=/Library/LaunchDaemons/org.nixos.nix-daemon.plist
+# create by default; set 0 to DIY, use a symlink, etc.
+readonly NIX_VOLUME_CREATE=${NIX_VOLUME_CREATE:-1} # now default
+NIX_FIRST_BUILD_UID="301"
+NIX_BUILD_USER_NAME_TEMPLATE="_nixbld%d"
+
+# caution: may update times on / if not run as normal non-root user
+read_only_root() {
+    # this touch command ~should~ always produce an error
+    # as of this change I confirmed /usr/bin/touch emits:
+    # "touch: /: Operation not permitted" Monterey
+    # "touch: /: Read-only file system" Catalina+ and Big Sur
+    # "touch: /: Permission denied" Mojave
+    # (not matching prefix for compat w/ coreutils touch in case using
+    # an explicit path causes problems; its prefix differs)
+    case "$(/usr/bin/touch / 2>&1)" in
+        *"Read-only file system") # Catalina, Big Sur
+            return 0
+            ;;
+        *"Operation not permitted") # Monterey
+            return 0
+            ;;
+        *)
+            return 1
+            ;;
+    esac
+
+    # Avoiding the slow semantic way to get this information (~330ms vs ~8ms)
+    # unless using touch causes problems. Just in case, that approach is:
+    # diskutil info -plist / | <find the Writable or WritableVolume keys>, i.e.
+    # diskutil info -plist / | xmllint --xpath "name(/plist/dict/key[text()='Writable']/following-sibling::*[1])" -
+}
+
+if read_only_root && [ "$NIX_VOLUME_CREATE" = 1 ]; then
+    should_create_volume() { return 0; }
+else
+    should_create_volume() { return 1; }
+fi
+
+# shellcheck source=./create-darwin-volume.sh
+. "$EXTRACTED_NIX_PATH/create-darwin-volume.sh" "no-main"
 
 dsclattr() {
     /usr/bin/dscl . -read "$1" \
-        | awk "/$2/ { print \$2 }"
+        | /usr/bin/awk "/$2/ { print \$2 }"
 }
 
-poly_validate_assumptions() {
-    if [ "$(uname -s)" != "Darwin" ]; then
-        failure "This script is for use with macOS!"
+test_nix_daemon_installed() {
+  test -e "$NIX_DAEMON_DEST"
+}
+
+poly_cure_artifacts() {
+    if should_create_volume; then
+        task "Fixing any leftover Nix volume state"
+        cat <<EOF
+Before I try to install, I'll check for any existing Nix volume config
+and ask for your permission to remove it (so that the installer can
+start fresh). I'll also ask for permission to fix any issues I spot.
+EOF
+        cure_volumes
+        remove_volume_artifacts
     fi
 }
 
 poly_service_installed_check() {
-    [ -e "$PLIST_DEST" ]
+    if should_create_volume; then
+        test_nix_daemon_installed || test_nix_volume_mountd_installed
+    else
+        test_nix_daemon_installed
+    fi
 }
 
 poly_service_uninstall_directions() {
-        cat <<EOF
-$1. Delete $PLIST_DEST
-
-  sudo launchctl unload $PLIST_DEST
-  sudo rm $PLIST_DEST
-
-EOF
+    echo "$1. Remove macOS-specific components:"
+    if should_create_volume && test_nix_volume_mountd_installed; then
+        nix_volume_mountd_uninstall_directions
+    fi
+    if test_nix_daemon_installed; then
+        nix_daemon_uninstall_directions
+    fi
 }
 
 poly_service_setup_note() {
-    cat <<EOF
- - load and start a LaunchDaemon (at $PLIST_DEST) for nix-daemon
-
-EOF
+    if should_create_volume; then
+        echo " - create a Nix volume and a LaunchDaemon to mount it"
+    fi
+    echo " - create a LaunchDaemon (at $NIX_DAEMON_DEST) for nix-daemon"
+    echo ""
 }
 
-poly_extra_try_me_commands(){
-  :
-}
-poly_extra_setup_instructions(){
-  :
+poly_extra_try_me_commands() {
+    :
 }
 
 poly_configure_nix_daemon_service() {
+    task "Setting up the nix-daemon LaunchDaemon"
     _sudo "to set up the nix-daemon as a LaunchDaemon" \
-          cp -f "/nix/var/nix/profiles/default$PLIST_DEST" "$PLIST_DEST"
+          /bin/cp -f "/nix/var/nix/profiles/default$NIX_DAEMON_DEST" "$NIX_DAEMON_DEST"
 
     _sudo "to load the LaunchDaemon plist for nix-daemon" \
           launchctl load /Library/LaunchDaemons/org.nixos.nix-daemon.plist
 
     _sudo "to start the nix-daemon" \
-          launchctl start org.nixos.nix-daemon
-
+          launchctl kickstart -k system/org.nixos.nix-daemon
 }
 
 poly_group_exists() {
@@ -94,6 +147,8 @@ poly_user_home_get() {
 }
 
 poly_user_home_set() {
+    # This can trigger a permission prompt now:
+    # "Terminal" would like to administer your computer. Administration can include modifying passwords, networking, and system settings.
     _sudo "in order to give $1 a safe home directory" \
           /usr/bin/dscl . -create "/Users/$1" "NFSHomeDirectory" "$2"
 }
@@ -119,7 +174,7 @@ poly_user_shell_set() {
 poly_user_in_group_check() {
     username=$1
     group=$2
-    dseditgroup -o checkmember -m "$username" "$group" > /dev/null 2>&1
+    /usr/sbin/dseditgroup -o checkmember -m "$username" "$group" > /dev/null 2>&1
 }
 
 poly_user_in_group_set() {
@@ -149,3 +204,21 @@ poly_create_build_user() {
           /usr/bin/dscl . create "/Users/$username" \
           UniqueID "${uid}"
 }
+
+poly_prepare_to_install() {
+    if should_create_volume; then
+        header "Preparing a Nix volume"
+        # intentional indent below to match task indent
+        cat <<EOF
+    Nix traditionally stores its data in the root directory $NIX_ROOT, but
+    macOS now (starting in 10.15 Catalina) has a read-only root directory.
+    To support Nix, I will create a volume and configure macOS to mount it
+    at $NIX_ROOT.
+EOF
+        setup_darwin_volume
+    fi
+
+    if [ "$(diskutil info -plist /nix | xmllint --xpath "(/plist/dict/key[text()='GlobalPermissionsEnabled'])/following-sibling::*[1]" -)" = "<false/>" ]; then
+        failure "This script needs a /nix volume with global permissions! This may require running sudo diskutil enableOwnership /nix."
+    fi
+}

scripts/install-multi-user.sh

@@ -25,13 +25,15 @@ readonly RED='\033[31m'
 readonly NIX_USER_COUNT=${NIX_USER_COUNT:-32}
 readonly NIX_BUILD_GROUP_ID="30000"
 readonly NIX_BUILD_GROUP_NAME="nixbld"
-readonly NIX_FIRST_BUILD_UID="30001"
+# darwin installer needs to override these
+NIX_FIRST_BUILD_UID="30001"
+NIX_BUILD_USER_NAME_TEMPLATE="nixbld%d"
 # Please don't change this. We don't support it, because the
 # default shell profile that comes with Nix doesn't support it.
 readonly NIX_ROOT="/nix"
 readonly NIX_EXTRA_CONF=${NIX_EXTRA_CONF:-}
 
-readonly PROFILE_TARGETS=("/etc/bashrc" "/etc/profile.d/nix.sh" "/etc/zshenv")
+readonly PROFILE_TARGETS=("/etc/bashrc" "/etc/profile.d/nix.sh" "/etc/zshrc" "/etc/bash.bashrc" "/etc/zsh/zshrc")
 readonly PROFILE_BACKUP_SUFFIX=".backup-before-nix"
 readonly PROFILE_NIX_FILE="$NIX_ROOT/var/nix/profiles/default/etc/profile.d/nix-daemon.sh"
 
@@ -41,7 +43,7 @@ readonly NIX_INSTALLED_CACERT="@cacert@"
 #readonly NIX_INSTALLED_CACERT="/nix/store/7dxhzymvy330i28ii676fl1pqwcahv2f-nss-cacert-3.49.2"
 readonly EXTRACTED_NIX_PATH="$(dirname "$0")"
 
-readonly ROOT_HOME=$(echo ~root)
+readonly ROOT_HOME=~root
 
 if [ -t 0 ]; then
     readonly IS_HEADLESS='no'
@@ -57,14 +59,19 @@ headless() {
     fi
 }
 
-contactme() {
+contact_us() {
+    echo "You can open an issue at https://github.com/nixos/nix/issues"
+    echo ""
+    echo "Or feel free to contact the team:"
+    echo " - Matrix: #nix:nixos.org"
+    echo " - IRC: in #nixos on irc.libera.chat"
+    echo " - twitter: @nixos_org"
+    echo " - forum: https://discourse.nixos.org"
+}
+get_help() {
     echo "We'd love to help if you need it."
     echo ""
-    echo "If you can, open an issue at https://github.com/nixos/nix/issues"
-    echo ""
-    echo "Or feel free to contact the team,"
-    echo " - on IRC #nixos on irc.freenode.net"
-    echo " - on twitter @nixos_org"
+    contact_us
 }
 
 uninstall_directions() {
@@ -100,11 +107,10 @@ $step. Delete the files Nix added to your system:
 and that is it.
 
 EOF
-
 }
 
 nix_user_for_core() {
-    printf "nixbld%d" "$1"
+    printf "$NIX_BUILD_USER_NAME_TEMPLATE" "$1"
 }
 
 nix_uid_for_core() {
@@ -168,7 +174,7 @@ failure() {
     header "oh no!"
     _textout "$RED" "$@"
     echo ""
-    _textout "$RED" "$(contactme)"
+    _textout "$RED" "$(get_help)"
     trap finish_cleanup EXIT
     exit 1
 }
@@ -199,6 +205,95 @@ ui_confirm() {
     return 1
 }
 
+printf -v _UNCHANGED_GRP_FMT "%b" $'\033[2m%='"$ESC" # "dim"
+# bold+invert+red and bold+invert+green just for the +/- below
+# red/green foreground for rest of the line
+printf -v _OLD_LINE_FMT "%b" $'\033[1;7;31m-'"$ESC ${RED}%L${ESC}"
+printf -v _NEW_LINE_FMT "%b" $'\033[1;7;32m+'"$ESC ${GREEN}%L${ESC}"
+
+_diff() {
+    # simple colorized diff comatible w/ pre `--color` versions
+    diff --unchanged-group-format="$_UNCHANGED_GRP_FMT" --old-line-format="$_OLD_LINE_FMT" --new-line-format="$_NEW_LINE_FMT" --unchanged-line-format="  %L" "$@"
+}
+
+confirm_rm() {
+    local path="$1"
+    if ui_confirm "Can I remove $path?"; then
+        _sudo "to remove $path" rm "$path"
+    fi
+}
+
+confirm_edit() {
+    local path="$1"
+    local edit_path="$2"
+    cat <<EOF
+
+Nix isn't the only thing in $path,
+but I think I know how to edit it out.
+Here's the diff:
+EOF
+
+    # could technically test the diff, but caller should do it
+    _diff "$path" "$edit_path"
+    if ui_confirm "Does the change above look right?"; then
+        _sudo "remove nix from $path" cp "$edit_path" "$path"
+    fi
+}
+
+_SERIOUS_BUSINESS="${RED}%s:${ESC} "
+password_confirm() {
+    local do_something_consequential="$1"
+    if ui_confirm "Can I $do_something_consequential?"; then
+        # shellcheck disable=SC2059
+        sudo -kv --prompt="$(printf "${_SERIOUS_BUSINESS}" "Enter your password to $do_something_consequential")"
+    else
+        return 1
+    fi
+}
+
+# Support accumulating reminders over the course of a run and showing
+# them at the end. An example where this helps: the installer changes
+# something, but it won't work without a reboot. If you tell the user
+# when you do it, they may miss it in the stream. The value of the
+# setting isn't enough to decide whether to message because you only
+# need to message if you *changed* it.
+
+# reminders stored in array delimited by empty entry; if ! headless,
+# user is asked to confirm after each delimiter.
+_reminders=()
+((_remind_num=1))
+
+remind() {
+    # (( arithmetic expression ))
+    if (( _remind_num > 1 )); then
+        header "Reminders"
+        for line in "${_reminders[@]}"; do
+            echo "$line"
+            if ! headless && [ "${#line}" = 0 ]; then
+                if read -r -p "Press enter/return to acknowledge."; then
+                    printf $'\033[A\33[2K\r'
+                fi
+            fi
+        done
+    fi
+}
+
+reminder() {
+    printf -v label "${BLUE}[ %d ]${ESC}" "$_remind_num"
+    _reminders+=("$label")
+    if [[ "$*" = "" ]]; then
+        while read -r line; do
+            _reminders+=("$line")
+        done
+    else
+        # this expands each arg to an array entry (and each entry will
+        # ultimately be a separate line in the output)
+        _reminders+=("$@")
+    fi
+    _reminders+=("")
+    ((_remind_num++))
+}
+
 __sudo() {
     local expl="$1"
     local cmd="$2"
@@ -219,18 +314,18 @@ _sudo() {
     local expl="$1"
     shift
     if ! headless; then
-        __sudo "$expl" "$*"
+        __sudo "$expl" "$*" >&2
     fi
     sudo "$@"
 }
 
 
-readonly SCRATCH=$(mktemp -d -t tmp.XXXXXXXXXX)
-function finish_cleanup {
+readonly SCRATCH=$(mktemp -d "${TMPDIR:-/tmp/}tmp.XXXXXXXXXX")
+finish_cleanup() {
     rm -rf "$SCRATCH"
 }
 
-function finish_fail {
+finish_fail() {
     finish_cleanup
 
     failure <<EOF
@@ -242,45 +337,46 @@ EOF
 }
 trap finish_fail EXIT
 
-channel_update_failed=0
-function finish_success {
-    finish_cleanup
-
+finish_success() {
     ok "Alright! We're done!"
-    if [ "x$channel_update_failed" = x1 ]; then
-        echo ""
-        echo "But fetching the nixpkgs channel failed. (Are you offline?)"
-        echo "To try again later, run \"sudo -i nix-channel --update nixpkgs\"."
-    fi
 
     cat <<EOF
-
-Before Nix will work in your existing shells, you'll need to close
-them and open them again. Other than that, you should be ready to go.
-
 Try it! Open a new terminal, and type:
 $(poly_extra_try_me_commands)
   $ nix-shell -p nix-info --run "nix-info -m"
-$(poly_extra_setup_instructions)
-Thank you for using this installer. If you have any feedback, don't
-hesitate:
 
-$(contactme)
+Thank you for using this installer. If you have any feedback or need
+help, don't hesitate:
+
+$(contact_us)
 EOF
-
+    remind
+    finish_cleanup
 }
 
+finish_uninstall_success() {
+    ok "Alright! Nix should be removed!"
+
+    cat <<EOF
+If you spot anything this uninstaller missed or have feedback,
+don't hesitate:
+
+$(contact_us)
+EOF
+    remind
+    finish_cleanup
+}
+
+remove_nix_artifacts() {
+    failure "Not implemented yet"
+}
+
+cure_artifacts() {
+    poly_cure_artifacts
+    # remove_nix_artifacts (LATER)
+}
 
 validate_starting_assumptions() {
-    poly_validate_assumptions
-
-    if [ $EUID -eq 0 ]; then
-        failure <<EOF
-Please do not run this script with root privileges. We will call sudo
-when we need to.
-EOF
-    fi
-
     if type nix-env 2> /dev/null >&2; then
         warning <<EOF
 Nix already appears to be installed. This installer may run into issues.
@@ -442,18 +538,46 @@ create_build_users() {
 
 create_directories() {
     # FIXME: remove all of this because it duplicates LocalStore::LocalStore().
+    task "Setting up the basic directory structure"
+    if [ -d "$NIX_ROOT" ]; then
+        # if /nix already exists, take ownership
+        #
+        # Caution: notes below are macOS-y
+        # This is a bit of a goldilocks zone for taking ownership
+        # if there are already files on the volume; the volume is
+        # now mounted, but we haven't added a bunch of new files
 
+        # this is probably a bit slow; I've been seeing 3.3-4s even
+        # when promptly installed over a fresh single-user install.
+        # In case anyone's aware of a shortcut.
+        # `|| true`: .Trashes errors w/o full disk perm
+
+        # rumor per #4488 that macOS 11.2 may not have
+        # sbin on path, and that's where chown is, but
+        # since this bit is cross-platform:
+        # - first try with `command -vp` to try and find
+        #   chown in the usual places
+        # - fall back on `command -v` which would find
+        #   any chown on path
+        # if we don't find one, the command is already
+        # hiding behind || true, and the general state
+        # should be one the user can repair once they
+        # figure out where chown is...
+        local get_chr_own="$(command -vp chown)"
+        if [[ -z "$get_chr_own" ]]; then
+            get_chr_own="$(command -v chown)"
+        fi
+        _sudo "to take root ownership of existing Nix store files" \
+              "$get_chr_own" -R "root:$NIX_BUILD_GROUP_NAME" "$NIX_ROOT" || true
+    fi
     _sudo "to make the basic directory structure of Nix (part 1)" \
-          mkdir -pv -m 0755 /nix /nix/var /nix/var/log /nix/var/log/nix /nix/var/log/nix/drvs /nix/var/nix{,/db,/gcroots,/profiles,/temproots,/userpool} /nix/var/nix/{gcroots,profiles}/per-user
+          install -dv -m 0755 /nix /nix/var /nix/var/log /nix/var/log/nix /nix/var/log/nix/drvs /nix/var/nix{,/db,/gcroots,/profiles,/temproots,/userpool} /nix/var/nix/{gcroots,profiles}/per-user
 
     _sudo "to make the basic directory structure of Nix (part 2)" \
-          mkdir -pv -m 1775 /nix/store
-
-    _sudo "to make the basic directory structure of Nix (part 3)" \
-          chgrp "$NIX_BUILD_GROUP_NAME" /nix/store
+          install -dv -g "$NIX_BUILD_GROUP_NAME" -m 1775 /nix/store
 
     _sudo "to place the default nix daemon configuration (part 1)" \
-          mkdir -pv -m 0555 /etc/nix
+          install -dv -m 0555 /etc/nix
 }
 
 place_channel_configuration() {
@@ -473,7 +597,7 @@ This installation tool will set up your computer with the Nix package
 manager. This will happen in a few stages:
 
 1. Make sure your computer doesn't already have Nix. If it does, I
-   will show you instructions on how to clean up your old one.
+   will show you instructions on how to clean up your old install.
 
 2. Show you what we are going to install and where. Then we will ask
    if you are ready to continue.
@@ -572,11 +696,15 @@ EOF
 }
 
 install_from_extracted_nix() {
+    task "Installing Nix"
     (
         cd "$EXTRACTED_NIX_PATH"
 
         _sudo "to copy the basic Nix files to the new store at $NIX_ROOT/store" \
-              rsync -rlpt --chmod=-w ./store/* "$NIX_ROOT/store/"
+              cp -RLp ./store/* "$NIX_ROOT/store/"
+
+        _sudo "to make the new store non-writable at $NIX_ROOT/store" \
+              chmod -R ugo-w "$NIX_ROOT/store/"
 
         if [ -d "$NIX_INSTALLED_NIX" ]; then
             echo "      Alright! We have our first nix at $NIX_INSTALLED_NIX"
@@ -587,9 +715,8 @@ $NIX_INSTALLED_NIX.
 EOF
         fi
 
-        cat ./.reginfo \
-            | _sudo "to load data for the first time in to the Nix Database" \
-                   "$NIX_INSTALLED_NIX/bin/nix-store" --load-db
+        _sudo "to load data for the first time in to the Nix Database" \
+              "$NIX_INSTALLED_NIX/bin/nix-store" --load-db < ./.reginfo
 
         echo "      Just finished getting the nix database ready."
     )
@@ -608,6 +735,7 @@ EOF
 }
 
 configure_shell_profile() {
+    task "Setting up shell profiles: ${PROFILE_TARGETS[*]}"
     for profile_target in "${PROFILE_TARGETS[@]}"; do
         if [ -e "$profile_target" ]; then
             _sudo "to back up your current $profile_target to $profile_target$PROFILE_BACKUP_SUFFIX" \
@@ -627,14 +755,27 @@ configure_shell_profile() {
                         tee -a "$profile_target"
         fi
     done
+    # TODO: should we suggest '. $PROFILE_NIX_FILE'? It would get them on
+    # their way less disruptively, but a counter-argument is that they won't
+    # immediately notice if something didn't get set up right?
+    reminder "Nix won't work in active shell sessions until you restart them."
+}
+
+cert_in_store() {
+    # in a subshell
+    # - change into the cert-file dir
+    # - get the phyiscal pwd
+    # and test if this path is in the Nix store
+    [[ "$(cd -- "$(dirname "$NIX_SSL_CERT_FILE")" && exec pwd -P)" == "$NIX_ROOT/store/"* ]]
 }
 
 setup_default_profile() {
-    _sudo "to installing a bootstrapping Nix in to the default Profile" \
+    task "Setting up the default profile"
+    _sudo "to install a bootstrapping Nix in to the default profile" \
           HOME="$ROOT_HOME" "$NIX_INSTALLED_NIX/bin/nix-env" -i "$NIX_INSTALLED_NIX"
 
-    if [ -z "${NIX_SSL_CERT_FILE:-}" ] || ! [ -f "${NIX_SSL_CERT_FILE:-}" ]; then
-        _sudo "to installing a bootstrapping SSL certificate just for Nix in to the default Profile" \
+    if [ -z "${NIX_SSL_CERT_FILE:-}" ] || ! [ -f "${NIX_SSL_CERT_FILE:-}" ] || cert_in_store; then
+        _sudo "to install a bootstrapping SSL certificate just for Nix in to the default profile" \
               HOME="$ROOT_HOME" "$NIX_INSTALLED_NIX/bin/nix-env" -i "$NIX_INSTALLED_CACERT"
         export NIX_SSL_CERT_FILE=/nix/var/nix/profiles/default/etc/ssl/certs/ca-bundle.crt
     fi
@@ -643,9 +784,13 @@ setup_default_profile() {
         # Have to explicitly pass NIX_SSL_CERT_FILE as part of the sudo call,
         # otherwise it will be lost in environments where sudo doesn't pass
         # all the environment variables by default.
-        _sudo "to update the default channel in the default profile" \
-            HOME="$ROOT_HOME" NIX_SSL_CERT_FILE="$NIX_SSL_CERT_FILE" "$NIX_INSTALLED_NIX/bin/nix-channel" --update nixpkgs \
-            || channel_update_failed=1
+        if ! _sudo "to update the default channel in the default profile" \
+            HOME="$ROOT_HOME" NIX_SSL_CERT_FILE="$NIX_SSL_CERT_FILE" "$NIX_INSTALLED_NIX/bin/nix-channel" --update nixpkgs; then
+            reminder <<EOF
+I had trouble fetching the nixpkgs channel (are you offline?)
+To try again later, run: sudo -i nix-channel --update nixpkgs
+EOF
+        fi
     fi
 }
 
@@ -660,6 +805,17 @@ EOF
 }
 
 main() {
+    # TODO: I've moved this out of validate_starting_assumptions so we
+    # can fail faster in this case. Sourcing install-darwin... now runs
+    # `touch /` to detect Read-only root, but it could update times on
+    # pre-Catalina macOS if run as root user.
+    if [ $EUID -eq 0 ]; then
+        failure <<EOF
+Please do not run this script with root privileges. We will call sudo
+when we need to.
+EOF
+    fi
+
     if [ "$(uname -s)" = "Darwin" ]; then
         # shellcheck source=./install-darwin-multi-user.sh
         . "$EXTRACTED_NIX_PATH/install-darwin-multi-user.sh"
@@ -673,17 +829,24 @@ main() {
     welcome_to_nix
     chat_about_sudo
 
+    cure_artifacts
+    # TODO: there's a tension between cure and validate. I moved the
+    # the sudo/root check out of validate to the head of this func.
+    # Cure is *intended* to subsume the validate-and-abort approach,
+    # so it may eventually obsolete it.
     validate_starting_assumptions
 
     setup_report
 
     if ! ui_confirm "Ready to continue?"; then
         ok "Alright, no changes have been made :)"
-        contactme
+        get_help
         trap finish_cleanup EXIT
         exit 1
     fi
 
+    poly_prepare_to_install
+
     create_build_group
     create_build_users
     create_directories
@@ -693,6 +856,7 @@ main() {
     configure_shell_profile
 
     set +eu
+    # shellcheck disable=SC1091
     . /etc/profile
     set -eu
 
@@ -704,5 +868,20 @@ main() {
     trap finish_success EXIT
 }
 
+# set an empty initial arg for bare invocations in case we need to
+# disambiguate someone directly invoking this later.
+if [ "${#@}" = 0 ]; then
+    set ""
+fi
 
-main
+# ACTION for override
+case "${1-}" in
+    # uninstall)
+    #     shift
+    #     uninstall "$@";;
+    # install == same as the no-arg condition for now (but, explicit)
+    ""|install)
+        main;;
+    *) # holding space for future options (like uninstall + install?)
+        failure "install-multi-user: invalid argument";;
+esac

scripts/install-nix-from-closure.sh

@@ -26,18 +26,9 @@ fi
 
 # macOS support for 10.12.6 or higher
 if [ "$(uname -s)" = "Darwin" ]; then
-    IFS='.' read macos_major macos_minor macos_patch << EOF
+    IFS='.' read -r macos_major macos_minor macos_patch << EOF
 $(sw_vers -productVersion)
 EOF
-    # TODO: this is a temporary speed-bump to keep people from naively installing Nix
-    # on macOS Big Sur (11.0+, 10.16+) until nixpkgs updates are ready for them.
-    # *Ideally* this is gone before next Nix release. If you're intentionally working on
-    # Nix + Big Sur, just comment out this block and be on your way :)
-    if [ "$macos_major" -gt 10 ] || { [ "$macos_major" -eq 10 ] && [ "$macos_minor" -gt 15 ]; }; then
-        echo "$0: nixpkgs isn't quite ready to support macOS $(sw_vers -productVersion) yet"
-        exit 1
-    fi
-
     if [ "$macos_major" -lt 10 ] || { [ "$macos_major" -eq 10 ] && [ "$macos_minor" -lt 12 ]; } || { [ "$macos_minor" -eq 12 ] && [ "$macos_patch" -lt 6 ]; }; then
         # patch may not be present; command substitution for simplicity
         echo "$0: macOS $(sw_vers -productVersion) is not supported, upgrade to 10.12.6 or higher"
@@ -46,21 +37,40 @@ EOF
 fi
 
 # Determine if we could use the multi-user installer or not
-if [ "$(uname -s)" = "Darwin" ]; then
-    echo "Note: a multi-user installation is possible. See https://nixos.org/nix/manual/#sect-multi-user-installation" >&2
-elif [ "$(uname -s)" = "Linux" ]; then
+if [ "$(uname -s)" = "Linux" ]; then
     echo "Note: a multi-user installation is possible. See https://nixos.org/nix/manual/#sect-multi-user-installation" >&2
 fi
 
-INSTALL_MODE=no-daemon
-CREATE_DARWIN_VOLUME=0
+case "$(uname -s)" in
+    "Darwin")
+        INSTALL_MODE=daemon;;
+    *)
+        INSTALL_MODE=no-daemon;;
+esac
+
+# space-separated string
+ACTIONS=
+
 # handle the command line flags
 while [ $# -gt 0 ]; do
     case $1 in
         --daemon)
-            INSTALL_MODE=daemon;;
+            INSTALL_MODE=daemon
+            ACTIONS="${ACTIONS}install "
+            ;;
         --no-daemon)
-            INSTALL_MODE=no-daemon;;
+            if [ "$(uname -s)" = "Darwin" ]; then
+                printf '\e[1;31mError: --no-daemon installs are no-longer supported on Darwin/macOS!\e[0m\n' >&2
+                exit 1
+            fi
+            INSTALL_MODE=no-daemon
+            # intentional tail space
+            ACTIONS="${ACTIONS}install "
+            ;;
+        # --uninstall)
+        #     # intentional tail space
+        #     ACTIONS="${ACTIONS}uninstall "
+        #     ;;
         --no-channel-add)
             export NIX_INSTALLER_NO_CHANNEL_ADD=1;;
         --daemon-user-count)
@@ -69,13 +79,18 @@ while [ $# -gt 0 ]; do
         --no-modify-profile)
             NIX_INSTALLER_NO_MODIFY_PROFILE=1;;
         --darwin-use-unencrypted-nix-store-volume)
-            CREATE_DARWIN_VOLUME=1;;
+            {
+                echo "Warning: the flag --darwin-use-unencrypted-nix-store-volume"
+                echo "         is no longer needed and will be removed in the future."
+                echo ""
+            } >&2;;
         --nix-extra-conf-file)
-            export NIX_EXTRA_CONF="$(cat $2)"
+            # shellcheck disable=SC2155
+            export NIX_EXTRA_CONF="$(cat "$2")"
             shift;;
         *)
-            (
-                echo "Nix Installer [--daemon|--no-daemon] [--daemon-user-count INT] [--no-channel-add] [--no-modify-profile] [--darwin-use-unencrypted-nix-store-volume] [--nix-extra-conf-file FILE]"
+            {
+                echo "Nix Installer [--daemon|--no-daemon] [--daemon-user-count INT] [--no-channel-add] [--no-modify-profile] [--nix-extra-conf-file FILE]"
 
                 echo "Choose installation method."
                 echo ""
@@ -91,55 +106,25 @@ while [ $# -gt 0 ]; do
                 echo ""
                 echo " --no-channel-add:    Don't add any channels. nixpkgs-unstable is installed by default."
                 echo ""
-                echo " --no-modify-profile: Skip channel installation. When not provided nixpkgs-unstable"
-                echo "                      is installed by default."
+                echo " --no-modify-profile: Don't modify the user profile to automatically load nix."
                 echo ""
                 echo " --daemon-user-count: Number of build users to create. Defaults to 32."
                 echo ""
-                echo " --nix-extra-conf-file: Path to nix.conf to prepend when installing /etc/nix.conf"
+                echo " --nix-extra-conf-file: Path to nix.conf to prepend when installing /etc/nix/nix.conf"
                 echo ""
                 if [ -n "${INVOKED_FROM_INSTALL_IN:-}" ]; then
                     echo " --tarball-url-prefix URL: Base URL to download the Nix tarball from."
                 fi
-            ) >&2
+            } >&2
 
-            # darwin and Catalina+
-            if [ "$(uname -s)" = "Darwin" ] && { [ "$macos_major" -gt 10 ] || { [ "$macos_major" -eq 10 ] && [ "$macos_minor" -gt 14 ]; }; }; then
-                (
-                    echo " --darwin-use-unencrypted-nix-store-volume: Create an APFS volume for the Nix"
-                    echo "              store and mount it at /nix. This is the recommended way to create"
-                    echo "              /nix with a read-only / on macOS >=10.15."
-                    echo "              See: https://nixos.org/nix/manual/#sect-macos-installation"
-                    echo ""
-                ) >&2
-            fi
             exit;;
     esac
     shift
 done
 
-if [ "$(uname -s)" = "Darwin" ]; then
-    if [ "$CREATE_DARWIN_VOLUME" = 1 ]; then
-        printf '\e[1;31mCreating volume and mountpoint /nix.\e[0m\n'
-        "$self/create-darwin-volume.sh"
-    fi
-
-    writable="$(diskutil info -plist / | xmllint --xpath "name(/plist/dict/key[text()='Writable']/following-sibling::*[1])" -)"
-    if ! [ -e $dest ] && [ "$writable" = "false" ]; then
-        (
-            echo ""
-            echo "Installing on macOS >=10.15 requires relocating the store to an apfs volume."
-            echo "Use sh <(curl -L https://nixos.org/nix/install) --darwin-use-unencrypted-nix-store-volume or run the preparation steps manually."
-            echo "See https://nixos.org/nix/manual/#sect-macos-installation"
-            echo ""
-        ) >&2
-        exit 1
-    fi
-fi
-
 if [ "$INSTALL_MODE" = "daemon" ]; then
     printf '\e[1;31mSwitching to the Multi-user Installer\e[0m\n'
-    exec "$self/install-multi-user"
+    exec "$self/install-multi-user" $ACTIONS # let ACTIONS split
     exit 0
 fi
 
@@ -194,6 +179,7 @@ if ! "$nix/bin/nix-store" --load-db < "$self/.reginfo"; then
     exit 1
 fi
 
+# shellcheck source=./nix-profile.sh.in
 . "$nix/etc/profile.d/nix.sh"
 
 if ! "$nix/bin/nix-env" -i "$nix"; then

scripts/install-systemd-multi-user.sh

@@ -41,10 +41,8 @@ handle_network_proxy() {
     fi
 }
 
-poly_validate_assumptions() {
-    if [ "$(uname -s)" != "Linux" ]; then
-        failure "This script is for use with Linux!"
-    fi
+poly_cure_artifacts() {
+    :
 }
 
 poly_service_installed_check() {
@@ -72,7 +70,7 @@ poly_service_setup_note() {
 EOF
 }
 
-poly_extra_try_me_commands(){
+poly_extra_try_me_commands() {
     if [ -e /run/systemd/system ]; then
         :
     else
@@ -81,19 +79,10 @@ poly_extra_try_me_commands(){
 EOF
     fi
 }
-poly_extra_setup_instructions(){
-    if [ -e /run/systemd/system ]; then
-        :
-    else
-        cat <<EOF
-Additionally, you may want to add nix-daemon to your init-system.
-
-EOF
-    fi
-}
 
 poly_configure_nix_daemon_service() {
     if [ -e /run/systemd/system ]; then
+        task "Setting up the nix-daemon systemd service"
         _sudo "to set up the nix-daemon service" \
               systemctl link "/nix/var/nix/profiles/default$SERVICE_SRC"
 
@@ -110,6 +99,8 @@ poly_configure_nix_daemon_service() {
 
         _sudo "to start the nix-daemon.service" \
               systemctl restart nix-daemon.service
+    else
+        reminder "I don't support your init system yet; you may want to add nix-daemon manually."
     fi
 }
 
@@ -207,3 +198,7 @@ poly_create_build_user() {
           --password "!" \
           "$username"
 }
+
+poly_prepare_to_install() {
+    :
+}

scripts/install.in

@@ -40,27 +40,31 @@ case "$(uname -s).$(uname -m)" in
         path=@tarballPath_aarch64-linux@
         system=aarch64-linux
         ;;
+    Linux.armv6l_linux)
+        hash=@tarballHash_armv6l-linux@
+        path=@tarballPath_armv6l-linux@
+        system=armv6l-linux
+        ;;
+    Linux.armv7l_linux)
+        hash=@tarballHash_armv7l-linux@
+        path=@tarballPath_armv7l-linux@
+        system=armv7l-linux
+        ;;
     Darwin.x86_64)
         hash=@tarballHash_x86_64-darwin@
         path=@tarballPath_x86_64-darwin@
         system=x86_64-darwin
         ;;
     Darwin.arm64|Darwin.aarch64)
-        # check for Rosetta 2 support
-        if ! [ -f /Library/Apple/System/Library/LaunchDaemons/com.apple.oahd.plist ]; then
-          oops "Rosetta 2 is not installed on this ARM64 macOS machine. Run softwareupdate --install-rosetta then restart installation"
-        fi
-
-        hash=@binaryTarball_x86_64-darwin@
-        path=@tarballPath_x86_64-darwin@
-        # eventually maybe: aarch64-darwin
-        system=x86_64-darwin
+        hash=@tarballHash_aarch64-darwin@
+        path=@tarballPath_aarch64-darwin@
+        system=aarch64-darwin
         ;;
     *) oops "sorry, there is no binary distribution of Nix for your platform";;
 esac
 
 # Use this command-line option to fetch the tarballs using nar-serve or Cachix
-if "${1:---tarball-url-prefix}"; then
+if [ "${1:-}" = "--tarball-url-prefix" ]; then
     if [ -z "${2:-}" ]; then
         oops "missing argument for --tarball-url-prefix"
     fi
@@ -72,14 +76,21 @@ fi
 
 tarball=$tmpDir/nix-@nixVersion@-$system.tar.xz
 
-require_util curl "download the binary tarball"
 require_util tar "unpack the binary tarball"
 if [ "$(uname -s)" != "Darwin" ]; then
     require_util xz "unpack the binary tarball"
 fi
 
+if command -v wget > /dev/null 2>&1; then
+    fetch() { wget "$1" -O "$2"; }
+elif command -v curl > /dev/null 2>&1; then
+    fetch() { curl -L "$1" -o "$2"; }
+else
+    oops "you don't have wget or curl installed, which I need to download the binary tarball"
+fi
+
 echo "downloading Nix @nixVersion@ binary tarball for $system from '$url' to '$tmpDir'..."
-curl -L "$url" -o "$tarball" || oops "failed to download '$url'"
+fetch "$url" "$tarball" || oops "failed to download '$url'"
 
 if command -v sha256sum > /dev/null 2>&1; then
     hash2="$(sha256sum -b "$tarball" | cut -c1-64)"

scripts/prepare-installer-for-github-actions

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+set -e
+
+script=$(nix-build -A outputs.hydraJobs.installerScriptForGHA --no-out-link)
+installerHash=$(echo $script | cut -b12-43 -)
+
+installerURL=https://$CACHIX_NAME.cachix.org/serve/$installerHash/install
+
+echo "::set-output name=installerURL::$installerURL"

src/build-remote/build-remote.cc

@@ -53,6 +53,9 @@ static int main_build_remote(int argc, char * * argv)
         unsetenv("DISPLAY");
         unsetenv("SSH_ASKPASS");
 
+        /* If we ever use the common args framework, make sure to
+           remove initPlugins below and initialize settings first.
+        */
         if (argc != 2)
             throw UsageError("called without required arguments");
 
@@ -127,11 +130,14 @@ static int main_build_remote(int argc, char * * argv)
                 for (auto & m : machines) {
                     debug("considering building on remote machine '%s'", m.storeUri);
 
-                    if (m.enabled && std::find(m.systemTypes.begin(),
-                            m.systemTypes.end(),
-                            neededSystem) != m.systemTypes.end() &&
+                    if (m.enabled
+                        && (neededSystem == "builtin"
+                            || std::find(m.systemTypes.begin(),
+                                m.systemTypes.end(),
+                                neededSystem) != m.systemTypes.end()) &&
                         m.allSupported(requiredFeatures) &&
-                        m.mandatoryMet(requiredFeatures)) {
+                        m.mandatoryMet(requiredFeatures))
+                    {
                         rightType = true;
                         AutoCloseFD free;
                         uint64_t load = 0;
@@ -248,7 +254,7 @@ connected:
         std::cerr << "# accept\n" << storeUri << "\n";
 
         auto inputs = readStrings<PathSet>(source);
-        auto outputs = readStrings<PathSet>(source);
+        auto wantedOutputs = readStrings<StringSet>(source);
 
         AutoCloseFD uploadLock = openLockFile(currentLoad + "/" + escapeUri(storeUri) + ".upload-lock", true);
 
@@ -267,29 +273,65 @@ connected:
 
         {
             Activity act(*logger, lvlTalkative, actUnknown, fmt("copying dependencies to '%s'", storeUri));
-            copyPaths(store, ref<Store>(sshStore), store->parseStorePathSet(inputs), NoRepair, NoCheckSigs, substitute);
+            copyPaths(*store, *sshStore, store->parseStorePathSet(inputs), NoRepair, NoCheckSigs, substitute);
         }
 
         uploadLock = -1;
 
         auto drv = store->readDerivation(*drvPath);
-        drv.inputSrcs = store->parseStorePathSet(inputs);
+        auto outputHashes = staticOutputHashes(*store, drv);
+
+        // Hijack the inputs paths of the derivation to include all the paths
+        // that come from the `inputDrvs` set.
+        // We don’t do that for the derivations whose `inputDrvs` is empty
+        // because
+        // 1. It’s not needed
+        // 2. Changing the `inputSrcs` set changes the associated output ids,
+        //  which break CA derivations
+        if (!drv.inputDrvs.empty())
+            drv.inputSrcs = store->parseStorePathSet(inputs);
 
         auto result = sshStore->buildDerivation(*drvPath, drv);
 
         if (!result.success())
             throw Error("build of '%s' on '%s' failed: %s", store->printStorePath(*drvPath), storeUri, result.errorMsg);
 
-        StorePathSet missing;
-        for (auto & path : outputs)
-            if (!store->isValidPath(store->parseStorePath(path))) missing.insert(store->parseStorePath(path));
+        std::set<Realisation> missingRealisations;
+        StorePathSet missingPaths;
+        if (settings.isExperimentalFeatureEnabled("ca-derivations") && !derivationHasKnownOutputPaths(drv.type())) {
+            for (auto & outputName : wantedOutputs) {
+                auto thisOutputHash = outputHashes.at(outputName);
+                auto thisOutputId = DrvOutput{ thisOutputHash, outputName };
+                if (!store->queryRealisation(thisOutputId)) {
+                    debug("missing output %s", outputName);
+                    assert(result.builtOutputs.count(thisOutputId));
+                    auto newRealisation = result.builtOutputs.at(thisOutputId);
+                    missingRealisations.insert(newRealisation);
+                    missingPaths.insert(newRealisation.outPath);
+                }
+            }
+        } else {
+            auto outputPaths = drv.outputsAndOptPaths(*store);
+            for (auto & [outputName, hopefullyOutputPath] : outputPaths) {
+                assert(hopefullyOutputPath.second);
+                if (!store->isValidPath(*hopefullyOutputPath.second))
+                    missingPaths.insert(*hopefullyOutputPath.second);
+            }
+        }
 
-        if (!missing.empty()) {
+        if (!missingPaths.empty()) {
             Activity act(*logger, lvlTalkative, actUnknown, fmt("copying outputs from '%s'", storeUri));
             if (auto localStore = store.dynamic_pointer_cast<LocalStore>())
-                for (auto & i : missing)
-                    localStore->locksHeld.insert(store->printStorePath(i)); /* FIXME: ugly */
-            copyPaths(ref<Store>(sshStore), store, missing, NoRepair, NoCheckSigs, NoSubstitute);
+                for (auto & path : missingPaths)
+                    localStore->locksHeld.insert(store->printStorePath(path)); /* FIXME: ugly */
+            copyPaths(*sshStore, *store, missingPaths, NoRepair, NoCheckSigs, NoSubstitute);
+        }
+        // XXX: Should be done as part of `copyPaths`
+        for (auto & realisation : missingRealisations) {
+            // Should hold, because if the feature isn't enabled the set
+            // of missing realisations should be empty
+            settings.requireExperimentalFeature("ca-derivations");
+            store->registerDrvOutput(realisation);
         }
 
         return 0;

src/libcmd/command.cc

@@ -54,7 +54,31 @@ void StoreCommand::run()
     run(getStore());
 }
 
-RealisedPathsCommand::RealisedPathsCommand(bool recursive)
+EvalCommand::EvalCommand()
+{
+}
+
+EvalCommand::~EvalCommand()
+{
+    if (evalState)
+        evalState->printStats();
+}
+
+ref<Store> EvalCommand::getEvalStore()
+{
+    if (!evalStore)
+        evalStore = evalStoreUrl ? openStore(*evalStoreUrl) : getStore();
+    return ref<Store>(evalStore);
+}
+
+ref<EvalState> EvalCommand::getEvalState()
+{
+    if (!evalState)
+        evalState = std::make_shared<EvalState>(searchPath, getEvalStore(), getStore());
+    return ref<EvalState>(evalState);
+}
+
+BuiltPathsCommand::BuiltPathsCommand(bool recursive)
     : recursive(recursive)
 {
     if (recursive)
@@ -81,47 +105,54 @@ RealisedPathsCommand::RealisedPathsCommand(bool recursive)
     });
 }
 
-void RealisedPathsCommand::run(ref<Store> store)
+void BuiltPathsCommand::run(ref<Store> store)
 {
-    std::vector<RealisedPath> paths;
+    BuiltPaths paths;
     if (all) {
         if (installables.size())
             throw UsageError("'--all' does not expect arguments");
         // XXX: Only uses opaque paths, ignores all the realisations
         for (auto & p : store->queryAllValidPaths())
-            paths.push_back(p);
+            paths.push_back(BuiltPath::Opaque{p});
     } else {
-        auto pathSet = toRealisedPaths(store, realiseMode, operateOn, installables);
+        paths = toBuiltPaths(getEvalStore(), store, realiseMode, operateOn, installables);
         if (recursive) {
-            auto roots = std::move(pathSet);
-            pathSet = {};
-            RealisedPath::closure(*store, roots, pathSet);
+            // XXX: This only computes the store path closure, ignoring
+            // intermediate realisations
+            StorePathSet pathsRoots, pathsClosure;
+            for (auto & root : paths) {
+                auto rootFromThis = root.outPaths();
+                pathsRoots.insert(rootFromThis.begin(), rootFromThis.end());
+            }
+            store->computeFSClosure(pathsRoots, pathsClosure);
+            for (auto & path : pathsClosure)
+                paths.push_back(BuiltPath::Opaque{path});
         }
-        for (auto & path : pathSet)
-            paths.push_back(path);
     }
 
     run(store, std::move(paths));
 }
 
 StorePathsCommand::StorePathsCommand(bool recursive)
-    : RealisedPathsCommand(recursive)
+    : BuiltPathsCommand(recursive)
 {
 }
 
-void StorePathsCommand::run(ref<Store> store, std::vector<RealisedPath> paths)
+void StorePathsCommand::run(ref<Store> store, BuiltPaths && paths)
 {
-    StorePaths storePaths;
-    for (auto & p : paths)
-        storePaths.push_back(p.path());
+    StorePathSet storePaths;
+    for (auto & builtPath : paths)
+        for (auto & p : builtPath.outPaths())
+            storePaths.insert(p);
 
-    run(store, std::move(storePaths));
+    auto sorted = store->topoSortPaths(storePaths);
+    std::reverse(sorted.begin(), sorted.end());
+
+    run(store, std::move(sorted));
 }
 
-void StorePathCommand::run(ref<Store> store)
+void StorePathCommand::run(ref<Store> store, std::vector<StorePath> && storePaths)
 {
-    auto storePaths = toStorePaths(store, Realise::Nothing, operateOn, installables);
-
     if (storePaths.size() != 1)
         throw UsageError("this command requires exactly one store path");
 
@@ -164,7 +195,7 @@ void MixProfile::updateProfile(const StorePath & storePath)
             profile2, storePath));
 }
 
-void MixProfile::updateProfile(const Buildables & buildables)
+void MixProfile::updateProfile(const BuiltPaths & buildables)
 {
     if (!profile) return;
 
@@ -172,22 +203,19 @@ void MixProfile::updateProfile(const Buildables & buildables)
 
     for (auto & buildable : buildables) {
         std::visit(overloaded {
-            [&](BuildableOpaque bo) {
+            [&](const BuiltPath::Opaque & bo) {
                 result.push_back(bo.path);
             },
-            [&](BuildableFromDrv bfd) {
+            [&](const BuiltPath::Built & bfd) {
                 for (auto & output : bfd.outputs) {
-                    /* Output path should be known because we just tried to
-                       build it. */
-                    assert(output.second);
-                    result.push_back(*output.second);
+                    result.push_back(output.second);
                 }
             },
-        }, buildable);
+        }, buildable.raw());
     }
 
     if (result.size() != 1)
-        throw Error("'--profile' requires that the arguments produce a single store path, but there are %d", result.size());
+        throw UsageError("'--profile' requires that the arguments produce a single store path, but there are %d", result.size());
 
     updateProfile(result[0]);
 }

src/libcmd/command.hh

@@ -45,8 +45,17 @@ private:
 
 struct EvalCommand : virtual StoreCommand, MixEvalArgs
 {
+    EvalCommand();
+
+    ~EvalCommand();
+
+    ref<Store> getEvalStore();
+
     ref<EvalState> getEvalState();
 
+private:
+    std::shared_ptr<Store> evalStore;
+
     std::shared_ptr<EvalState> evalState;
 };
 
@@ -99,6 +108,8 @@ enum class Realise {
        exists. */
     Derivation,
     /* Evaluate in dry-run mode. Postcondition: nothing. */
+    // FIXME: currently unused, but could be revived if we can
+    // evaluate derivations in-memory.
     Nothing
 };
 
@@ -141,7 +152,7 @@ private:
 };
 
 /* A command that operates on zero or more store paths. */
-struct RealisedPathsCommand : public InstallablesCommand
+struct BuiltPathsCommand : public InstallablesCommand
 {
 private:
 
@@ -154,36 +165,36 @@ protected:
 
 public:
 
-    RealisedPathsCommand(bool recursive = false);
+    BuiltPathsCommand(bool recursive = false);
 
     using StoreCommand::run;
 
-    virtual void run(ref<Store> store, std::vector<RealisedPath> paths) = 0;
+    virtual void run(ref<Store> store, BuiltPaths && paths) = 0;
 
     void run(ref<Store> store) override;
 
     bool useDefaultInstallables() override { return !all; }
 };
 
-struct StorePathsCommand : public RealisedPathsCommand
+struct StorePathsCommand : public BuiltPathsCommand
 {
     StorePathsCommand(bool recursive = false);
 
-    using RealisedPathsCommand::run;
+    using BuiltPathsCommand::run;
 
-    virtual void run(ref<Store> store, std::vector<StorePath> storePaths) = 0;
+    virtual void run(ref<Store> store, std::vector<StorePath> && storePaths) = 0;
 
-    void run(ref<Store> store, std::vector<RealisedPath> paths) override;
+    void run(ref<Store> store, BuiltPaths && paths) override;
 };
 
 /* A command that operates on exactly one store path. */
-struct StorePathCommand : public InstallablesCommand
+struct StorePathCommand : public StorePathsCommand
 {
-    using StoreCommand::run;
+    using StorePathsCommand::run;
 
     virtual void run(ref<Store> store, const StorePath & storePath) = 0;
 
-    void run(ref<Store> store) override;
+    void run(ref<Store> store, std::vector<StorePath> && storePaths) override;
 };
 
 /* A helper class for registering commands globally. */
@@ -214,26 +225,37 @@ static RegisterCommand registerCommand2(std::vector<std::string> && name)
     return RegisterCommand(std::move(name), [](){ return make_ref<T>(); });
 }
 
-Buildables build(ref<Store> store, Realise mode,
-    std::vector<std::shared_ptr<Installable>> installables, BuildMode bMode = bmNormal);
+BuiltPaths build(
+    ref<Store> evalStore,
+    ref<Store> store, Realise mode,
+    const std::vector<std::shared_ptr<Installable>> & installables,
+    BuildMode bMode = bmNormal);
 
-std::set<StorePath> toStorePaths(ref<Store> store,
-    Realise mode, OperateOn operateOn,
-    std::vector<std::shared_ptr<Installable>> installables);
-
-StorePath toStorePath(ref<Store> store,
-    Realise mode, OperateOn operateOn,
-    std::shared_ptr<Installable> installable);
-
-std::set<StorePath> toDerivations(ref<Store> store,
-    std::vector<std::shared_ptr<Installable>> installables,
-    bool useDeriver = false);
-
-std::set<RealisedPath> toRealisedPaths(
+std::set<StorePath> toStorePaths(
+    ref<Store> evalStore,
     ref<Store> store,
     Realise mode,
     OperateOn operateOn,
-    std::vector<std::shared_ptr<Installable>> installables);
+    const std::vector<std::shared_ptr<Installable>> & installables);
+
+StorePath toStorePath(
+    ref<Store> evalStore,
+    ref<Store> store,
+    Realise mode,
+    OperateOn operateOn,
+    std::shared_ptr<Installable> installable);
+
+std::set<StorePath> toDerivations(
+    ref<Store> store,
+    const std::vector<std::shared_ptr<Installable>> & installables,
+    bool useDeriver = false);
+
+BuiltPaths toBuiltPaths(
+    ref<Store> evalStore,
+    ref<Store> store,
+    Realise mode,
+    OperateOn operateOn,
+    const std::vector<std::shared_ptr<Installable>> & installables);
 
 /* Helper function to generate args that invoke $EDITOR on
    filename:lineno. */
@@ -250,7 +272,7 @@ struct MixProfile : virtual StoreCommand
 
     /* If 'profile' is set, make it point at the store path produced
        by 'buildables'. */
-    void updateProfile(const Buildables & buildables);
+    void updateProfile(const BuiltPaths & buildables);
 };
 
 struct MixDefaultProfile : MixProfile

src/libcmd/installables.cc

@@ -20,31 +20,6 @@
 
 namespace nix {
 
-nlohmann::json BuildableOpaque::toJSON(ref<Store> store) const {
-    nlohmann::json res;
-    res["path"] = store->printStorePath(path);
-    return res;
-}
-
-nlohmann::json BuildableFromDrv::toJSON(ref<Store> store) const {
-    nlohmann::json res;
-    res["drvPath"] = store->printStorePath(drvPath);
-    for (const auto& [output, path] : outputs) {
-        res["outputs"][output] = path ? store->printStorePath(*path) : "";
-    }
-    return res;
-}
-
-nlohmann::json buildablesToJSON(const Buildables & buildables, ref<Store> store) {
-    auto res = nlohmann::json::array();
-    for (const Buildable & buildable : buildables) {
-        std::visit([&res, store](const auto & buildable) {
-            res.push_back(buildable.toJSON(store));
-        }, buildable);
-    }
-    return res;
-}
-
 void completeFlakeInputPath(
     ref<EvalState> evalState,
     const FlakeRef & flakeRef,
@@ -83,9 +58,13 @@ MixFlakeOptions::MixFlakeOptions()
 
     addFlag({
         .longName = "no-registries",
-        .description = "Don't allow lookups in the flake registries.",
+        .description =
+          "Don't allow lookups in the flake registries. This option is deprecated; use `--no-use-registries`.",
         .category = category,
-        .handler = {&lockFlags.useRegistries, false}
+        .handler = {[&]() {
+            lockFlags.useRegistries = false;
+            warn("'--no-registries' is deprecated; use '--no-use-registries'");
+        }}
     });
 
     addFlag({
@@ -111,10 +90,11 @@ MixFlakeOptions::MixFlakeOptions()
 
     addFlag({
         .longName = "override-input",
-        .description = "Override a specific flake input (e.g. `dwarffs/nixpkgs`).",
+        .description = "Override a specific flake input (e.g. `dwarffs/nixpkgs`). This implies `--no-write-lock-file`.",
         .category = category,
         .labels = {"input-path", "flake-url"},
         .handler = {[&](std::string inputPath, std::string flakeRef) {
+            lockFlags.writeLockFile = false;
             lockFlags.inputOverrides.insert_or_assign(
                 flake::parseInputPath(inputPath),
                 parseFlakeRef(flakeRef, absPath(".")));
@@ -195,14 +175,50 @@ Strings SourceExprCommand::getDefaultFlakeAttrPathPrefixes()
 
 void SourceExprCommand::completeInstallable(std::string_view prefix)
 {
-    if (file) return; // FIXME
+    if (file) {
+        evalSettings.pureEval = false;
+        auto state = getEvalState();
+        Expr *e = state->parseExprFromFile(
+            resolveExprPath(state->checkSourcePath(lookupFileArg(*state, *file)))
+        );
 
-    completeFlakeRefWithFragment(
-        getEvalState(),
-        lockFlags,
-        getDefaultFlakeAttrPathPrefixes(),
-        getDefaultFlakeAttrPaths(),
-        prefix);
+        Value root;
+        state->eval(e, root);
+
+        auto autoArgs = getAutoArgs(*state);
+
+        std::string prefix_ = std::string(prefix);
+        auto sep = prefix_.rfind('.');
+        std::string searchWord;
+        if (sep != std::string::npos) {
+            searchWord = prefix_.substr(sep, std::string::npos);
+            prefix_ = prefix_.substr(0, sep);
+        } else {
+            searchWord = prefix_;
+            prefix_ = "";
+        }
+
+        Value &v1(*findAlongAttrPath(*state, prefix_, *autoArgs, root).first);
+        state->forceValue(v1);
+        Value v2;
+        state->autoCallFunction(*autoArgs, v1, v2);
+
+        if (v2.type() == nAttrs) {
+            for (auto & i : *v2.attrs) {
+                std::string name = i.name;
+                if (name.find(searchWord) == 0) {
+                    completions->add(i.name);
+                }
+            }
+        }
+    } else {
+        completeFlakeRefWithFragment(
+            getEvalState(),
+            lockFlags,
+            getDefaultFlakeAttrPathPrefixes(),
+            getDefaultFlakeAttrPaths(),
+            prefix);
+    }
 }
 
 void completeFlakeRefWithFragment(
@@ -273,13 +289,6 @@ void completeFlakeRefWithFragment(
     completeFlakeRef(evalState->store, prefix);
 }
 
-ref<EvalState> EvalCommand::getEvalState()
-{
-    if (!evalState)
-        evalState = std::make_shared<EvalState>(searchPath, getStore());
-    return ref<EvalState>(evalState);
-}
-
 void completeFlakeRef(ref<Store> store, std::string_view prefix)
 {
     if (prefix == "")
@@ -303,9 +312,9 @@ void completeFlakeRef(ref<Store> store, std::string_view prefix)
     }
 }
 
-Buildable Installable::toBuildable()
+DerivedPath Installable::toDerivedPath()
 {
-    auto buildables = toBuildables();
+    auto buildables = toDerivedPaths();
     if (buildables.size() != 1)
         throw Error("installable '%s' evaluates to %d derivations, where only one is expected", what(), buildables.size());
     return std::move(buildables[0]);
@@ -339,22 +348,19 @@ struct InstallableStorePath : Installable
 
     std::string what() override { return store->printStorePath(storePath); }
 
-    Buildables toBuildables() override
+    DerivedPaths toDerivedPaths() override
     {
         if (storePath.isDerivation()) {
-            std::map<std::string, std::optional<StorePath>> outputs;
             auto drv = store->readDerivation(storePath);
-            for (auto & [name, output] : drv.outputsAndOptPaths(*store))
-                outputs.emplace(name, output.second);
             return {
-                BuildableFromDrv {
+                DerivedPath::Built {
                     .drvPath = storePath,
-                    .outputs = std::move(outputs)
+                    .outputs = drv.outputNames(),
                 }
             };
         } else {
             return {
-                BuildableOpaque {
+                DerivedPath::Opaque {
                     .path = storePath,
                 }
             };
@@ -367,22 +373,24 @@ struct InstallableStorePath : Installable
     }
 };
 
-Buildables InstallableValue::toBuildables()
+DerivedPaths InstallableValue::toDerivedPaths()
 {
-    Buildables res;
+    DerivedPaths res;
 
-    std::map<StorePath, std::map<std::string, std::optional<StorePath>>> drvsToOutputs;
+    std::map<StorePath, std::set<std::string>> drvsToOutputs;
+    RealisedPath::Set drvsToCopy;
 
     // Group by derivation, helps with .all in particular
     for (auto & drv : toDerivations()) {
         auto outputName = drv.outputName;
         if (outputName == "")
             throw Error("derivation '%s' lacks an 'outputName' attribute", state->store->printStorePath(drv.drvPath));
-        drvsToOutputs[drv.drvPath].insert_or_assign(outputName, drv.outPath);
+        drvsToOutputs[drv.drvPath].insert(outputName);
+        drvsToCopy.insert(drv.drvPath);
     }
 
     for (auto & i : drvsToOutputs)
-        res.push_back(BuildableFromDrv { i.first, i.second });
+        res.push_back(DerivedPath::Built { i.first, i.second });
 
     return res;
 }
@@ -496,6 +504,23 @@ static std::string showAttrPaths(const std::vector<std::string> & paths)
     return s;
 }
 
+InstallableFlake::InstallableFlake(
+    SourceExprCommand * cmd,
+    ref<EvalState> state,
+    FlakeRef && flakeRef,
+    Strings && attrPaths,
+    Strings && prefixes,
+    const flake::LockFlags & lockFlags)
+    : InstallableValue(state),
+      flakeRef(flakeRef),
+      attrPaths(attrPaths),
+      prefixes(prefixes),
+      lockFlags(lockFlags)
+{
+    if (cmd && cmd->getAutoArgs(*state)->size())
+        throw UsageError("'--arg' and '--argstr' are incompatible with flakes");
+}
+
 std::tuple<std::string, FlakeRef, InstallableValue::DerivationInfo> InstallableFlake::toDerivation()
 {
     auto lockedFlake = getLockedFlake();
@@ -504,7 +529,11 @@ std::tuple<std::string, FlakeRef, InstallableValue::DerivationInfo> InstallableF
     auto root = cache->getRoot();
 
     for (auto & attrPath : getActualAttrPaths()) {
-        auto attr = root->findAlongAttrPath(parseAttrPath(*state, attrPath));
+        auto attr = root->findAlongAttrPath(
+            parseAttrPath(*state, attrPath),
+            true
+        );
+
         if (!attr) continue;
 
         if (!attr->isDerivation())
@@ -573,10 +602,10 @@ InstallableFlake::getCursors(EvalState & state)
 
 std::shared_ptr<flake::LockedFlake> InstallableFlake::getLockedFlake() const
 {
+    flake::LockFlags lockFlagsApplyConfig = lockFlags;
+    lockFlagsApplyConfig.applyNixConfig = true;
     if (!_lockedFlake) {
-        _lockedFlake = std::make_shared<flake::LockedFlake>(lockFlake(*state, flakeRef, lockFlags));
-        _lockedFlake->flake.config.apply();
-        // FIXME: send new config to the daemon.
+        _lockedFlake = std::make_shared<flake::LockedFlake>(lockFlake(*state, flakeRef, lockFlagsApplyConfig));
     }
     return _lockedFlake;
 }
@@ -625,17 +654,6 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
         for (auto & s : ss) {
             std::exception_ptr ex;
 
-            try {
-                auto [flakeRef, fragment] = parseFlakeRefWithFragment(s, absPath("."));
-                result.push_back(std::make_shared<InstallableFlake>(
-                        getEvalState(), std::move(flakeRef),
-                        fragment == "" ? getDefaultFlakeAttrPaths() : Strings{fragment},
-                        getDefaultFlakeAttrPathPrefixes(), lockFlags));
-                continue;
-            } catch (...) {
-                ex = std::current_exception();
-            }
-
             if (s.find('/') != std::string::npos) {
                 try {
                     result.push_back(std::make_shared<InstallableStorePath>(store, store->followLinksToStorePath(s)));
@@ -647,14 +665,21 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
                 }
             }
 
-            std::rethrow_exception(ex);
+            try {
+                auto [flakeRef, fragment] = parseFlakeRefWithFragment(s, absPath("."));
+                result.push_back(std::make_shared<InstallableFlake>(
+                        this,
+                        getEvalState(),
+                        std::move(flakeRef),
+                        fragment == "" ? getDefaultFlakeAttrPaths() : Strings{fragment},
+                        getDefaultFlakeAttrPathPrefixes(),
+                        lockFlags));
+                continue;
+            } catch (...) {
+                ex = std::current_exception();
+            }
 
-            /*
-            throw Error(
-                pathExists(s)
-                ? "path '%s' is not a flake or a store path"
-                : "don't know how to handle argument '%s'", s);
-            */
+            std::rethrow_exception(ex);
         }
     }
 
@@ -669,108 +694,121 @@ std::shared_ptr<Installable> SourceExprCommand::parseInstallable(
     return installables.front();
 }
 
-Buildables build(ref<Store> store, Realise mode,
-    std::vector<std::shared_ptr<Installable>> installables, BuildMode bMode)
+BuiltPaths getBuiltPaths(ref<Store> evalStore, ref<Store> store, const DerivedPaths & hopefullyBuiltPaths)
 {
-    if (mode == Realise::Nothing)
-        settings.readOnlyMode = true;
-
-    Buildables buildables;
-
-    std::vector<StorePathWithOutputs> pathsToBuild;
-
-    for (auto & i : installables) {
-        for (auto & b : i->toBuildables()) {
-            std::visit(overloaded {
-                [&](BuildableOpaque bo) {
-                    pathsToBuild.push_back({bo.path});
+    BuiltPaths res;
+    for (const auto & b : hopefullyBuiltPaths)
+        std::visit(
+            overloaded{
+                [&](const DerivedPath::Opaque & bo) {
+                    res.push_back(BuiltPath::Opaque{bo.path});
                 },
-                [&](BuildableFromDrv bfd) {
-                    StringSet outputNames;
-                    for (auto & output : bfd.outputs)
-                        outputNames.insert(output.first);
-                    pathsToBuild.push_back({bfd.drvPath, outputNames});
-                },
-            }, b);
-            buildables.push_back(std::move(b));
-        }
-    }
-
-    if (mode == Realise::Nothing)
-        printMissing(store, pathsToBuild, lvlError);
-    else if (mode == Realise::Outputs)
-        store->buildPaths(pathsToBuild, bMode);
-
-    return buildables;
-}
-
-std::set<RealisedPath> toRealisedPaths(
-    ref<Store> store,
-    Realise mode,
-    OperateOn operateOn,
-    std::vector<std::shared_ptr<Installable>> installables)
-{
-    std::set<RealisedPath> res;
-    if (operateOn == OperateOn::Output) {
-        for (auto & b : build(store, mode, installables))
-            std::visit(overloaded {
-                [&](BuildableOpaque bo) {
-                    res.insert(bo.path);
-                },
-                [&](BuildableFromDrv bfd) {
-                    auto drv = store->readDerivation(bfd.drvPath);
-                    auto outputHashes = staticOutputHashes(*store, drv);
+                [&](const DerivedPath::Built & bfd) {
+                    OutputPathMap outputs;
+                    auto drv = evalStore->readDerivation(bfd.drvPath);
+                    auto outputHashes = staticOutputHashes(*evalStore, drv); // FIXME: expensive
+                    auto drvOutputs = drv.outputsAndOptPaths(*store);
                     for (auto & output : bfd.outputs) {
-                        if (settings.isExperimentalFeatureEnabled("ca-derivations")) {
-                            if (!outputHashes.count(output.first))
-                                throw Error(
-                                    "the derivation '%s' doesn't have an output named '%s'",
-                                    store->printStorePath(bfd.drvPath),
-                                    output.first);
-                            auto outputId = DrvOutput{outputHashes.at(output.first), output.first};
-                            auto realisation = store->queryRealisation(outputId);
+                        if (!outputHashes.count(output))
+                            throw Error(
+                                "the derivation '%s' doesn't have an output named '%s'",
+                                store->printStorePath(bfd.drvPath), output);
+                        if (settings.isExperimentalFeatureEnabled(
+                                "ca-derivations")) {
+                            auto outputId =
+                                DrvOutput{outputHashes.at(output), output};
+                            auto realisation =
+                                store->queryRealisation(outputId);
                             if (!realisation)
-                                throw Error("cannot operate on an output of unbuilt content-addresed derivation '%s'", outputId.to_string());
-                            res.insert(RealisedPath{*realisation});
-                        }
-                        else {
-                            // If ca-derivations isn't enabled, behave as if
-                            // all the paths are opaque to keep the default
-                            // behavior
-                            assert(output.second);
-                            res.insert(*output.second);
+                                throw Error(
+                                    "cannot operate on an output of unbuilt "
+                                    "content-addressed derivation '%s'",
+                                    outputId.to_string());
+                            outputs.insert_or_assign(
+                                output, realisation->outPath);
+                        } else {
+                            // If ca-derivations isn't enabled, assume that
+                            // the output path is statically known.
+                            assert(drvOutputs.count(output));
+                            assert(drvOutputs.at(output).second);
+                            outputs.insert_or_assign(
+                                output, *drvOutputs.at(output).second);
                         }
                     }
+                    res.push_back(BuiltPath::Built{bfd.drvPath, outputs});
                 },
-            }, b);
-    } else {
-        if (mode == Realise::Nothing)
-            settings.readOnlyMode = true;
-
-        for (auto & i : installables)
-            for (auto & b : i->toBuildables())
-                if (auto bfd = std::get_if<BuildableFromDrv>(&b))
-                    res.insert(bfd->drvPath);
-    }
+            },
+            b.raw());
 
     return res;
 }
 
-StorePathSet toStorePaths(ref<Store> store,
+BuiltPaths build(
+    ref<Store> evalStore,
+    ref<Store> store,
+    Realise mode,
+    const std::vector<std::shared_ptr<Installable>> & installables,
+    BuildMode bMode)
+{
+    if (mode == Realise::Nothing)
+        settings.readOnlyMode = true;
+
+    std::vector<DerivedPath> pathsToBuild;
+
+    for (auto & i : installables) {
+        auto b = i->toDerivedPaths();
+        pathsToBuild.insert(pathsToBuild.end(), b.begin(), b.end());
+    }
+
+    if (mode == Realise::Nothing || mode == Realise::Derivation)
+        printMissing(store, pathsToBuild, lvlError);
+    else if (mode == Realise::Outputs)
+        store->buildPaths(pathsToBuild, bMode, evalStore);
+
+    return getBuiltPaths(evalStore, store, pathsToBuild);
+}
+
+BuiltPaths toBuiltPaths(
+    ref<Store> evalStore,
+    ref<Store> store,
+    Realise mode,
+    OperateOn operateOn,
+    const std::vector<std::shared_ptr<Installable>> & installables)
+{
+    if (operateOn == OperateOn::Output)
+        return build(evalStore, store, mode, installables);
+    else {
+        if (mode == Realise::Nothing)
+            settings.readOnlyMode = true;
+
+        BuiltPaths res;
+        for (auto & drvPath : toDerivations(store, installables, true))
+            res.push_back(BuiltPath::Opaque{drvPath});
+        return res;
+    }
+}
+
+StorePathSet toStorePaths(
+    ref<Store> evalStore,
+    ref<Store> store,
     Realise mode, OperateOn operateOn,
-    std::vector<std::shared_ptr<Installable>> installables)
+    const std::vector<std::shared_ptr<Installable>> & installables)
 {
     StorePathSet outPaths;
-    for (auto & path : toRealisedPaths(store, mode, operateOn, installables))
-            outPaths.insert(path.path());
+    for (auto & path : toBuiltPaths(evalStore, store, mode, operateOn, installables)) {
+        auto thisOutPaths = path.outPaths();
+        outPaths.insert(thisOutPaths.begin(), thisOutPaths.end());
+    }
     return outPaths;
 }
 
-StorePath toStorePath(ref<Store> store,
+StorePath toStorePath(
+    ref<Store> evalStore,
+    ref<Store> store,
     Realise mode, OperateOn operateOn,
     std::shared_ptr<Installable> installable)
 {
-    auto paths = toStorePaths(store, mode, operateOn, {installable});
+    auto paths = toStorePaths(evalStore, store, mode, operateOn, {installable});
 
     if (paths.size() != 1)
         throw Error("argument '%s' should evaluate to one store path", installable->what());
@@ -778,15 +816,17 @@ StorePath toStorePath(ref<Store> store,
     return *paths.begin();
 }
 
-StorePathSet toDerivations(ref<Store> store,
-    std::vector<std::shared_ptr<Installable>> installables, bool useDeriver)
+StorePathSet toDerivations(
+    ref<Store> store,
+    const std::vector<std::shared_ptr<Installable>> & installables,
+    bool useDeriver)
 {
     StorePathSet drvPaths;
 
-    for (auto & i : installables)
-        for (auto & b : i->toBuildables())
+    for (const auto & i : installables)
+        for (const auto & b : i->toDerivedPaths())
             std::visit(overloaded {
-                [&](BuildableOpaque bo) {
+                [&](const DerivedPath::Opaque & bo) {
                     if (!useDeriver)
                         throw Error("argument '%s' did not evaluate to a derivation", i->what());
                     auto derivers = store->queryValidDerivers(bo.path);
@@ -795,10 +835,10 @@ StorePathSet toDerivations(ref<Store> store,
                     // FIXME: use all derivers?
                     drvPaths.insert(*derivers.begin());
                 },
-                [&](BuildableFromDrv bfd) {
+                [&](const DerivedPath::Built & bfd) {
                     drvPaths.insert(bfd.drvPath);
                 },
-            }, b);
+            }, b.raw());
 
     return drvPaths;
 }

src/libcmd/installables.hh

@@ -2,13 +2,13 @@
 
 #include "util.hh"
 #include "path.hh"
+#include "path-with-outputs.hh"
+#include "derived-path.hh"
 #include "eval.hh"
 #include "flake/flake.hh"
 
 #include <optional>
 
-#include <nlohmann/json_fwd.hpp>
-
 namespace nix {
 
 struct DrvInfo;
@@ -16,25 +16,6 @@ struct SourceExprCommand;
 
 namespace eval_cache { class EvalCache; class AttrCursor; }
 
-struct BuildableOpaque {
-    StorePath path;
-    nlohmann::json toJSON(ref<Store> store) const;
-};
-
-struct BuildableFromDrv {
-    StorePath drvPath;
-    std::map<std::string, std::optional<StorePath>> outputs;
-    nlohmann::json toJSON(ref<Store> store) const;
-};
-
-typedef std::variant<
-    BuildableOpaque,
-    BuildableFromDrv
-> Buildable;
-
-typedef std::vector<Buildable> Buildables;
-nlohmann::json buildablesToJSON(const Buildables & buildables, ref<Store> store);
-
 struct App
 {
     std::vector<StorePathWithOutputs> context;
@@ -42,17 +23,23 @@ struct App
     // FIXME: add args, sandbox settings, metadata, ...
 };
 
+struct UnresolvedApp
+{
+    App unresolved;
+    App resolve(ref<Store> evalStore, ref<Store> store);
+};
+
 struct Installable
 {
     virtual ~Installable() { }
 
     virtual std::string what() = 0;
 
-    virtual Buildables toBuildables() = 0;
+    virtual DerivedPaths toDerivedPaths() = 0;
 
-    Buildable toBuildable();
+    DerivedPath toDerivedPath();
 
-    App toApp(EvalState & state);
+    UnresolvedApp toApp(EvalState & state);
 
     virtual std::pair<Value *, Pos> toValue(EvalState & state)
     {
@@ -93,7 +80,7 @@ struct InstallableValue : Installable
 
     virtual std::vector<DerivationInfo> toDerivations() = 0;
 
-    Buildables toBuildables() override;
+    DerivedPaths toDerivedPaths() override;
 };
 
 struct InstallableFlake : InstallableValue
@@ -104,11 +91,13 @@ struct InstallableFlake : InstallableValue
     const flake::LockFlags & lockFlags;
     mutable std::shared_ptr<flake::LockedFlake> _lockedFlake;
 
-    InstallableFlake(ref<EvalState> state, FlakeRef && flakeRef,
-        Strings && attrPaths, Strings && prefixes, const flake::LockFlags & lockFlags)
-        : InstallableValue(state), flakeRef(flakeRef), attrPaths(attrPaths),
-          prefixes(prefixes), lockFlags(lockFlags)
-    { }
+    InstallableFlake(
+        SourceExprCommand * cmd,
+        ref<EvalState> state,
+        FlakeRef && flakeRef,
+        Strings && attrPaths,
+        Strings && prefixes,
+        const flake::LockFlags & lockFlags);
 
     std::string what() override { return flakeRef.to_string() + "#" + *attrPaths.begin(); }
 

src/libcmd/local.mk

@@ -8,8 +8,8 @@ libcmd_SOURCES := $(wildcard $(d)/*.cc)
 
 libcmd_CXXFLAGS += -I src/libutil -I src/libstore -I src/libexpr -I src/libmain -I src/libfetchers
 
-libcmd_LDFLAGS = -llowdown
+libcmd_LDFLAGS += -llowdown -pthread
 
 libcmd_LIBS = libstore libutil libexpr libmain libfetchers
 
-$(eval $(call install-file-in, $(d)/nix-cmd.pc, $(prefix)/lib/pkgconfig, 0644))
+$(eval $(call install-file-in, $(d)/nix-cmd.pc, $(libdir)/pkgconfig, 0644))

src/libcmd/markdown.cc

@@ -12,7 +12,7 @@ std::string renderMarkdownToTerminal(std::string_view markdown)
     struct lowdown_opts opts {
         .type = LOWDOWN_TERM,
         .maxdepth = 20,
-        .cols = std::min(getWindowSize().second, (unsigned short) 80),
+        .cols = std::max(getWindowSize().second, (unsigned short) 80),
         .hmargin = 0,
         .vmargin = 0,
         .feat = LOWDOWN_COMMONMARK | LOWDOWN_FENCED | LOWDOWN_DEFLIST | LOWDOWN_TABLES,
@@ -25,7 +25,7 @@ std::string renderMarkdownToTerminal(std::string_view markdown)
     Finally freeDoc([&]() { lowdown_doc_free(doc); });
 
     size_t maxn = 0;
-    auto node = lowdown_doc_parse(doc, &maxn, markdown.data(), markdown.size());
+    auto node = lowdown_doc_parse(doc, &maxn, markdown.data(), markdown.size(), nullptr);
     if (!node)
         throw Error("cannot parse Markdown document");
     Finally freeNode([&]() { lowdown_node_free(node); });
@@ -40,11 +40,11 @@ std::string renderMarkdownToTerminal(std::string_view markdown)
         throw Error("cannot allocate Markdown output buffer");
     Finally freeBuffer([&]() { lowdown_buf_free(buf); });
 
-    int rndr_res = lowdown_term_rndr(buf, nullptr, renderer, node);
+    int rndr_res = lowdown_term_rndr(buf, renderer, node);
     if (!rndr_res)
         throw Error("allocation error while rendering Markdown");
 
-    return std::string(buf->data, buf->size);
+    return filterANSIEscapes(std::string(buf->data, buf->size), !shouldANSI());
 }
 
 }

src/libexpr/attr-path.cc

@@ -19,7 +19,7 @@ static Strings parseAttrPath(std::string_view s)
             ++i;
             while (1) {
                 if (i == s.end())
-                    throw Error("missing closing quote in selection path '%1%'", s);
+                    throw ParseError("missing closing quote in selection path '%1%'", s);
                 if (*i == '"') break;
                 cur.push_back(*i++);
             }
@@ -100,7 +100,7 @@ std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attr
 }
 
 
-Pos findDerivationFilename(EvalState & state, Value & v, std::string what)
+Pos findPackageFilename(EvalState & state, Value & v, std::string what)
 {
     Value * v2;
     try {
@@ -116,14 +116,14 @@ Pos findDerivationFilename(EvalState & state, Value & v, std::string what)
 
     auto colon = pos.rfind(':');
     if (colon == std::string::npos)
-        throw Error("cannot parse meta.position attribute '%s'", pos);
+        throw ParseError("cannot parse meta.position attribute '%s'", pos);
 
     std::string filename(pos, 0, colon);
     unsigned int lineno;
     try {
         lineno = std::stoi(std::string(pos, colon + 1));
     } catch (std::invalid_argument & e) {
-        throw Error("cannot parse line number '%s'", pos);
+        throw ParseError("cannot parse line number '%s'", pos);
     }
 
     Symbol file = state.symbols.create(filename);

src/libexpr/attr-path.hh

@@ -14,7 +14,7 @@ std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const string & attr
     Bindings & autoArgs, Value & vIn);
 
 /* Heuristic to find the filename and lineno or a nix value. */
-Pos findDerivationFilename(EvalState & state, Value & v, std::string what);
+Pos findPackageFilename(EvalState & state, Value & v, std::string what);
 
 std::vector<Symbol> parseAttrPath(EvalState & state, std::string_view s);
 

src/libexpr/attr-set.hh

@@ -17,8 +17,8 @@ struct Attr
 {
     Symbol name;
     Value * value;
-    Pos * pos;
-    Attr(Symbol name, Value * value, Pos * pos = &noPos)
+    ptr<Pos> pos;
+    Attr(Symbol name, Value * value, ptr<Pos> pos = ptr(&noPos))
         : name(name), value(value), pos(pos) { };
     Attr() : pos(&noPos) { };
     bool operator < (const Attr & a) const
@@ -35,12 +35,13 @@ class Bindings
 {
 public:
     typedef uint32_t size_t;
+    ptr<Pos> pos;
 
 private:
     size_t size_, capacity_;
     Attr attrs[0];
 
-    Bindings(size_t capacity) : size_(0), capacity_(capacity) { }
+    Bindings(size_t capacity) : pos(&noPos), size_(0), capacity_(capacity) { }
     Bindings(const Bindings & bindings) = delete;
 
 public:

src/libexpr/common-eval-args.cc

@@ -61,6 +61,14 @@ MixEvalArgs::MixEvalArgs()
             fetchers::overrideRegistry(from.input, to.input, extraAttrs);
         }}
     });
+
+    addFlag({
+        .longName = "eval-store",
+        .description = "The Nix store to use for evaluations.",
+        .category = category,
+        .labels = {"store-url"},
+        .handler = {&evalStoreUrl},
+    });
 }
 
 Bindings * MixEvalArgs::getAutoArgs(EvalState & state)

src/libexpr/common-eval-args.hh

@@ -16,8 +16,9 @@ struct MixEvalArgs : virtual Args
 
     Strings searchPath;
 
-private:
+    std::optional<std::string> evalStoreUrl;
 
+private:
     std::map<std::string, std::string> autoArgs;
 };
 

src/libexpr/eval-cache.cc

@@ -486,11 +486,11 @@ std::shared_ptr<AttrCursor> AttrCursor::getAttr(std::string_view name)
     return getAttr(root->state.symbols.create(name));
 }
 
-std::shared_ptr<AttrCursor> AttrCursor::findAlongAttrPath(const std::vector<Symbol> & attrPath)
+std::shared_ptr<AttrCursor> AttrCursor::findAlongAttrPath(const std::vector<Symbol> & attrPath, bool force)
 {
     auto res = shared_from_this();
     for (auto & attr : attrPath) {
-        res = res->maybeGetAttr(attr);
+        res = res->maybeGetAttr(attr, force);
         if (!res) return {};
     }
     return res;

src/libexpr/eval-cache.hh

@@ -102,7 +102,7 @@ public:
 
     std::shared_ptr<AttrCursor> getAttr(std::string_view name);
 
-    std::shared_ptr<AttrCursor> findAlongAttrPath(const std::vector<Symbol> & attrPath);
+    std::shared_ptr<AttrCursor> findAlongAttrPath(const std::vector<Symbol> & attrPath, bool force = false);
 
     std::string getString();
 

src/libexpr/eval.cc

@@ -64,7 +64,11 @@ static char * dupStringWithLen(const char * s, size_t size)
 
 RootValue allocRootValue(Value * v)
 {
+#if HAVE_BOEHMGC
     return std::allocate_shared<Value *>(traceable_allocator<Value *>(), v);
+#else
+    return std::make_shared<Value *>(v);
+#endif
 }
 
 
@@ -201,6 +205,15 @@ string showType(const Value & v)
     }
 }
 
+Pos Value::determinePos(const Pos &pos) const
+{
+    switch (internalType) {
+        case tAttrs: return *attrs->pos;
+        case tLambda: return lambda.fun->pos;
+        case tApp: return app.left->determinePos(pos);
+        default: return pos;
+    }
+}
 
 bool Value::isTrivial() const
 {
@@ -224,22 +237,34 @@ static void * oomHandler(size_t requested)
 }
 
 class BoehmGCStackAllocator : public StackAllocator {
-  boost::coroutines2::protected_fixedsize_stack stack {
-    // We allocate 8 MB, the default max stack size on NixOS.
-    // A smaller stack might be quicker to allocate but reduces the stack
-    // depth available for source filter expressions etc.
-    std::max(boost::context::stack_traits::default_size(), static_cast<std::size_t>(8 * 1024 * 1024))
+    boost::coroutines2::protected_fixedsize_stack stack {
+        // We allocate 8 MB, the default max stack size on NixOS.
+        // A smaller stack might be quicker to allocate but reduces the stack
+        // depth available for source filter expressions etc.
+        std::max(boost::context::stack_traits::default_size(), static_cast<std::size_t>(8 * 1024 * 1024))
     };
 
+    // This is specific to boost::coroutines2::protected_fixedsize_stack.
+    // The stack protection page is included in sctx.size, so we have to
+    // subtract one page size from the stack size.
+    std::size_t pfss_usable_stack_size(boost::context::stack_context &sctx) {
+        return sctx.size - boost::context::stack_traits::page_size();
+    }
+
   public:
     boost::context::stack_context allocate() override {
         auto sctx = stack.allocate();
-        GC_add_roots(static_cast<char *>(sctx.sp) - sctx.size, sctx.sp);
+
+        // Stacks generally start at a high address and grow to lower addresses.
+        // Architectures that do the opposite are rare; in fact so rare that
+        // boost_routine does not implement it.
+        // So we subtract the stack size.
+        GC_add_roots(static_cast<char *>(sctx.sp) - pfss_usable_stack_size(sctx), sctx.sp);
         return sctx;
     }
 
     void deallocate(boost::context::stack_context sctx) override {
-        GC_remove_roots(static_cast<char *>(sctx.sp) - sctx.size, sctx.sp);
+        GC_remove_roots(static_cast<char *>(sctx.sp) - pfss_usable_stack_size(sctx), sctx.sp);
         stack.deallocate(sctx);
     }
 
@@ -353,7 +378,10 @@ static Strings parseNixPath(const string & s)
 }
 
 
-EvalState::EvalState(const Strings & _searchPath, ref<Store> store)
+EvalState::EvalState(
+    const Strings & _searchPath,
+    ref<Store> store,
+    std::shared_ptr<Store> buildStore)
     : sWith(symbols.create("<with>"))
     , sOutPath(symbols.create("outPath"))
     , sDrvPath(symbols.create("drvPath"))
@@ -386,6 +414,7 @@ EvalState::EvalState(const Strings & _searchPath, ref<Store> store)
     , sEpsilon(symbols.create(""))
     , repair(NoRepair)
     , store(store)
+    , buildStore(buildStore ? buildStore : store)
     , regexCache(makeRegexCache())
     , baseEnv(allocEnv(128))
     , staticBaseEnv(false, 0)
@@ -416,12 +445,12 @@ EvalState::EvalState(const Strings & _searchPath, ref<Store> store)
                     StorePathSet closure;
                     store->computeFSClosure(store->toStorePath(r.second).first, closure);
                     for (auto & path : closure)
-                        allowedPaths->insert(store->printStorePath(path));
+                        allowPath(path);
                 } catch (InvalidPath &) {
-                    allowedPaths->insert(r.second);
+                    allowPath(r.second);
                 }
             } else
-                allowedPaths->insert(r.second);
+                allowPath(r.second);
         }
     }
 
@@ -436,6 +465,35 @@ EvalState::~EvalState()
 }
 
 
+void EvalState::requireExperimentalFeatureOnEvaluation(
+    const std::string & feature,
+    const std::string_view fName,
+    const Pos & pos)
+{
+    if (!settings.isExperimentalFeatureEnabled(feature)) {
+        throw EvalError({
+            .msg = hintfmt(
+                "Cannot call '%2%' because experimental Nix feature '%1%' is disabled. You can enable it via '--extra-experimental-features %1%'.",
+                feature,
+                fName
+            ),
+            .errPos = pos
+        });
+    }
+}
+
+void EvalState::allowPath(const Path & path)
+{
+    if (allowedPaths)
+        allowedPaths->insert(path);
+}
+
+void EvalState::allowPath(const StorePath & storePath)
+{
+    if (allowedPaths)
+        allowedPaths->insert(store->toRealPath(storePath));
+}
+
 Path EvalState::checkSourcePath(const Path & path_)
 {
     if (!allowedPaths) return path_;
@@ -592,10 +650,8 @@ Value & EvalState::getBuiltin(const string & name)
 
 std::optional<EvalState::Doc> EvalState::getDoc(Value & v)
 {
-    if (v.isPrimOp() || v.isPrimOpApp()) {
+    if (v.isPrimOp()) {
         auto v2 = &v;
-        while (v2->isPrimOpApp())
-            v2 = v2->primOpApp.left;
         if (v2->primOp->doc)
             return Doc {
                 .pos = noPos,
@@ -743,7 +799,7 @@ inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
         }
         Bindings::iterator j = env->values[0]->attrs->find(var.name);
         if (j != env->values[0]->attrs->end()) {
-            if (countCalls && j->pos) attrSelects[*j->pos]++;
+            if (countCalls) attrSelects[*j->pos]++;
             return j->value;
         }
         if (!env->prevWith)
@@ -753,18 +809,10 @@ inline Value * EvalState::lookupVar(Env * env, const ExprVar & var, bool noEval)
 }
 
 
-std::atomic<uint64_t> nrValuesFreed{0};
-
-void finalizeValue(void * obj, void * data)
-{
-    nrValuesFreed++;
-}
-
 Value * EvalState::allocValue()
 {
     nrValues++;
     auto v = (Value *) allocBytes(sizeof(Value));
-    //GC_register_finalizer_no_order(v, finalizeValue, nullptr, nullptr, nullptr);
     return v;
 }
 
@@ -806,9 +854,9 @@ void EvalState::mkThunk_(Value & v, Expr * expr)
 }
 
 
-void EvalState::mkPos(Value & v, Pos * pos)
+void EvalState::mkPos(Value & v, ptr<Pos> pos)
 {
-    if (pos && pos->file.set()) {
+    if (pos->file.set()) {
         mkAttrs(v, 3);
         mkString(*allocAttr(v, sFile), pos->file);
         mkInt(*allocAttr(v, sLine), pos->line);
@@ -831,39 +879,37 @@ Value * Expr::maybeThunk(EvalState & state, Env & env)
 }
 
 
-unsigned long nrAvoided = 0;
-
 Value * ExprVar::maybeThunk(EvalState & state, Env & env)
 {
     Value * v = state.lookupVar(&env, *this, true);
     /* The value might not be initialised in the environment yet.
        In that case, ignore it. */
-    if (v) { nrAvoided++; return v; }
+    if (v) { state.nrAvoided++; return v; }
     return Expr::maybeThunk(state, env);
 }
 
 
 Value * ExprString::maybeThunk(EvalState & state, Env & env)
 {
-    nrAvoided++;
+    state.nrAvoided++;
     return &v;
 }
 
 Value * ExprInt::maybeThunk(EvalState & state, Env & env)
 {
-    nrAvoided++;
+    state.nrAvoided++;
     return &v;
 }
 
 Value * ExprFloat::maybeThunk(EvalState & state, Env & env)
 {
-    nrAvoided++;
+    state.nrAvoided++;
     return &v;
 }
 
 Value * ExprPath::maybeThunk(EvalState & state, Env & env)
 {
-    nrAvoided++;
+    state.nrAvoided++;
     return &v;
 }
 
@@ -878,38 +924,23 @@ void EvalState::evalFile(const Path & path_, Value & v, bool mustBeTrivial)
         return;
     }
 
-    Path path2 = resolveExprPath(path);
-    if ((i = fileEvalCache.find(path2)) != fileEvalCache.end()) {
+    Path resolvedPath = resolveExprPath(path);
+    if ((i = fileEvalCache.find(resolvedPath)) != fileEvalCache.end()) {
         v = i->second;
         return;
     }
 
-    printTalkative("evaluating file '%1%'", path2);
+    printTalkative("evaluating file '%1%'", resolvedPath);
     Expr * e = nullptr;
 
-    auto j = fileParseCache.find(path2);
+    auto j = fileParseCache.find(resolvedPath);
     if (j != fileParseCache.end())
         e = j->second;
 
     if (!e)
-        e = parseExprFromFile(checkSourcePath(path2));
+        e = parseExprFromFile(checkSourcePath(resolvedPath));
 
-    fileParseCache[path2] = e;
-
-    try {
-        // Enforce that 'flake.nix' is a direct attrset, not a
-        // computation.
-        if (mustBeTrivial &&
-            !(dynamic_cast<ExprAttrs *>(e)))
-            throw Error("file '%s' must be an attribute set", path);
-        eval(e, v);
-    } catch (Error & e) {
-        addErrorTrace(e, "while evaluating the file '%1%':", path2);
-        throw;
-    }
-
-    fileEvalCache[path2] = v;
-    if (path != path2) fileEvalCache[path] = v;
+    cacheFile(path, resolvedPath, e, v, mustBeTrivial);
 }
 
 
@@ -920,6 +951,32 @@ void EvalState::resetFileCache()
 }
 
 
+void EvalState::cacheFile(
+    const Path & path,
+    const Path & resolvedPath,
+    Expr * e,
+    Value & v,
+    bool mustBeTrivial)
+{
+    fileParseCache[resolvedPath] = e;
+
+    try {
+        // Enforce that 'flake.nix' is a direct attrset, not a
+        // computation.
+        if (mustBeTrivial &&
+            !(dynamic_cast<ExprAttrs *>(e)))
+            throw EvalError("file '%s' must be an attribute set", path);
+        eval(e, v);
+    } catch (Error & e) {
+        addErrorTrace(e, "while evaluating the file '%1%':", resolvedPath);
+        throw;
+    }
+
+    fileEvalCache[resolvedPath] = v;
+    if (path != resolvedPath) fileEvalCache[path] = v;
+}
+
+
 void EvalState::eval(Expr * e, Value & v)
 {
     e->eval(*this, baseEnv, v);
@@ -1010,7 +1067,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
             } else
                 vAttr = i.second.e->maybeThunk(state, i.second.inherited ? env : env2);
             env2.values[displ++] = vAttr;
-            v.attrs->push_back(Attr(i.first, vAttr, &i.second.pos));
+            v.attrs->push_back(Attr(i.first, vAttr, ptr(&i.second.pos)));
         }
 
         /* If the rec contains an attribute called `__overrides', then
@@ -1042,7 +1099,7 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
 
     else
         for (auto & i : attrs)
-            v.attrs->push_back(Attr(i.first, i.second.e->maybeThunk(state, env), &i.second.pos));
+            v.attrs->push_back(Attr(i.first, i.second.e->maybeThunk(state, env), ptr(&i.second.pos)));
 
     /* Dynamic attrs apply *after* rec and __overrides. */
     for (auto & i : dynamicAttrs) {
@@ -1059,9 +1116,11 @@ void ExprAttrs::eval(EvalState & state, Env & env, Value & v)
 
         i.valueExpr->setName(nameSym);
         /* Keep sorted order so find can catch duplicates */
-        v.attrs->push_back(Attr(nameSym, i.valueExpr->maybeThunk(state, *dynamicEnv), &i.pos));
+        v.attrs->push_back(Attr(nameSym, i.valueExpr->maybeThunk(state, *dynamicEnv), ptr(&i.pos)));
         v.attrs->sort(); // FIXME: inefficient
     }
+
+    v.attrs->pos = ptr(&pos);
 }
 
 
@@ -1116,12 +1175,10 @@ static string showAttrPath(EvalState & state, Env & env, const AttrPath & attrPa
 }
 
 
-unsigned long nrLookups = 0;
-
 void ExprSelect::eval(EvalState & state, Env & env, Value & v)
 {
     Value vTmp;
-    Pos * pos2 = 0;
+    ptr<Pos> pos2(&noPos);
     Value * vAttrs = &vTmp;
 
     e->eval(state, env, vTmp);
@@ -1129,7 +1186,7 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
     try {
 
         for (auto & i : attrPath) {
-            nrLookups++;
+            state.nrLookups++;
             Bindings::iterator j;
             Symbol name = getName(i, state, env);
             if (def) {
@@ -1147,13 +1204,13 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
             }
             vAttrs = j->value;
             pos2 = j->pos;
-            if (state.countCalls && pos2) state.attrSelects[*pos2]++;
+            if (state.countCalls) state.attrSelects[*pos2]++;
         }
 
-        state.forceValue(*vAttrs, ( pos2 != NULL ? *pos2 : this->pos ) );
+        state.forceValue(*vAttrs, (*pos2 != noPos ? *pos2 : this->pos ) );
 
     } catch (Error & e) {
-        if (pos2 && pos2->file != state.sDerivationNix)
+        if (*pos2 != noPos && pos2->file != state.sDerivationNix)
             addErrorTrace(e, *pos2, "while evaluating the attribute '%1%'",
                 showAttrPath(state, env, attrPath));
         throw;
@@ -1271,13 +1328,13 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & po
 
     auto size =
         (lambda.arg.empty() ? 0 : 1) +
-        (lambda.matchAttrs ? lambda.formals->formals.size() : 0);
+        (lambda.hasFormals() ? lambda.formals->formals.size() : 0);
     Env & env2(allocEnv(size));
     env2.up = fun.lambda.env;
 
     size_t displ = 0;
 
-    if (!lambda.matchAttrs)
+    if (!lambda.hasFormals())
         env2.values[displ++] = &arg;
 
     else {
@@ -1357,7 +1414,7 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
         }
     }
 
-    if (!fun.isLambda() || !fun.lambda.fun->matchAttrs) {
+    if (!fun.isLambda() || !fun.lambda.fun->hasFormals()) {
         res = fun;
         return;
     }
@@ -1381,10 +1438,10 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
             } else if (!i.def) {
                 throwMissingArgumentError(i.pos, R"(cannot evaluate a function that has an argument without a value ('%1%')
 
-nix attempted to evaluate a function as a top level expression; in this case it must have its
-arguments supplied either by default values, or passed explicitly with --arg or --argstr.
-
-https://nixos.org/manual/nix/stable/#ss-functions)", i.name);
+Nix attempted to evaluate a function as a top level expression; in
+this case it must have its arguments supplied either by default
+values, or passed explicitly with '--arg' or '--argstr'. See
+https://nixos.org/manual/nix/stable/#ss-functions.)", i.name);
 
             }
         }
@@ -1559,7 +1616,6 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
            and none of the strings are allowed to have contexts. */
         if (first) {
             firstType = vTmp.type();
-            first = false;
         }
 
         if (firstType == nInt) {
@@ -1580,7 +1636,12 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
             } else
                 throwEvalError(pos, "cannot add %1% to a float", showType(vTmp));
         } else
-            s << state.coerceToString(pos, vTmp, context, false, firstType == nString);
+            /* skip canonization of first path, which would only be not
+            canonized in the first place if it's coming from a ./${foo} type
+            path */
+            s << state.coerceToString(pos, vTmp, context, false, firstType == nString, !first);
+
+        first = false;
     }
 
     if (firstType == nInt)
@@ -1599,7 +1660,7 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
 
 void ExprPos::eval(EvalState & state, Env & env, Value & v)
 {
-    state.mkPos(v, &pos);
+    state.mkPos(v, ptr(&pos));
 }
 
 
@@ -1769,7 +1830,7 @@ std::optional<string> EvalState::tryAttrsToString(const Pos & pos, Value & v,
 }
 
 string EvalState::coerceToString(const Pos & pos, Value & v, PathSet & context,
-    bool coerceMore, bool copyToStore)
+    bool coerceMore, bool copyToStore, bool canonicalizePath)
 {
     forceValue(v, pos);
 
@@ -1781,7 +1842,7 @@ string EvalState::coerceToString(const Pos & pos, Value & v, PathSet & context,
     }
 
     if (v.type() == nPath) {
-        Path path(canonPath(v.path));
+        Path path(canonicalizePath ? canonPath(v.path) : v.path);
         return copyToStore ? copyPathToStore(context, path) : path;
     }
 
@@ -1840,6 +1901,7 @@ string EvalState::copyPathToStore(PathSet & context, const Path & path)
             ? store->computeStorePathForPath(std::string(baseNameOf(path)), checkSourcePath(path)).first
             : store->addToStore(std::string(baseNameOf(path)), checkSourcePath(path), FileIngestionMethod::Recursive, htSHA256, defaultPathFilter, repair);
         dstPath = store->printStorePath(p);
+        allowPath(p);
         srcToStore.insert_or_assign(path, std::move(p));
         printMsg(lvlChatty, "copied source '%1%' -> '%2%'", path, dstPath);
     }
@@ -2093,9 +2155,12 @@ Strings EvalSettings::getDefaultNixPath()
         }
     };
 
-    add(getHome() + "/.nix-defexpr/channels");
-    add(settings.nixStateDir + "/profiles/per-user/root/channels/nixpkgs", "nixpkgs");
-    add(settings.nixStateDir + "/profiles/per-user/root/channels");
+    if (!evalSettings.restrictEval && !evalSettings.pureEval) {
+        add(getHome() + "/.nix-defexpr/channels");
+        add(settings.nixStateDir + "/profiles/per-user/root/channels/nixpkgs", "nixpkgs");
+        add(settings.nixStateDir + "/profiles/per-user/root/channels");
+    }
+
     return res;
 }
 

src/libexpr/eval.hh

@@ -94,8 +94,14 @@ public:
 
     Value vEmptySet;
 
+    /* Store used to materialise .drv files. */
     const ref<Store> store;
 
+    /* Store used to build stuff. */
+    const ref<Store> buildStore;
+
+    RootValue vCallFlake = nullptr;
+    RootValue vImportedDrvToDerivation = nullptr;
 
 private:
     SrcToStore srcToStore;
@@ -128,13 +134,31 @@ private:
 
 public:
 
-    EvalState(const Strings & _searchPath, ref<Store> store);
+    EvalState(
+        const Strings & _searchPath,
+        ref<Store> store,
+        std::shared_ptr<Store> buildStore = nullptr);
     ~EvalState();
 
+    void requireExperimentalFeatureOnEvaluation(
+        const std::string & feature,
+        const std::string_view fName,
+        const Pos & pos
+    );
+
     void addToSearchPath(const string & s);
 
     SearchPath getSearchPath() { return searchPath; }
 
+    /* Allow access to a path. */
+    void allowPath(const Path & path);
+
+    /* Allow access to a store path. Note that this gets remapped to
+       the real store path if `store` is a chroot store. */
+    void allowPath(const StorePath & storePath);
+
+    /* Check whether access to a path is allowed and throw an error if
+       not. Otherwise return the canonicalised path. */
     Path checkSourcePath(const Path & path);
 
     void checkURI(const std::string & uri);
@@ -163,6 +187,14 @@ public:
        trivial (i.e. doesn't require arbitrary computation). */
     void evalFile(const Path & path, Value & v, bool mustBeTrivial = false);
 
+    /* Like `cacheFile`, but with an already parsed expression. */
+    void cacheFile(
+        const Path & path,
+        const Path & resolvedPath,
+        Expr * e,
+        Value & v,
+        bool mustBeTrivial = false);
+
     void resetFileCache();
 
     /* Look up a file in the search path. */
@@ -217,7 +249,8 @@ public:
        booleans and lists to a string.  If `copyToStore' is set,
        referenced paths are copied to the Nix store as a side effect. */
     string coerceToString(const Pos & pos, Value & v, PathSet & context,
-        bool coerceMore = false, bool copyToStore = true);
+        bool coerceMore = false, bool copyToStore = true,
+        bool canonicalizePath = true);
 
     string copyPathToStore(PathSet & context, const Path & path);
 
@@ -301,7 +334,7 @@ public:
     void mkList(Value & v, size_t length);
     void mkAttrs(Value & v, size_t capacity);
     void mkThunk_(Value & v, Expr * expr);
-    void mkPos(Value & v, Pos * pos);
+    void mkPos(Value & v, ptr<Pos> pos);
 
     void concatLists(Value & v, size_t nrLists, Value * * lists, const Pos & pos);
 
@@ -316,8 +349,10 @@ private:
     unsigned long nrValuesInEnvs = 0;
     unsigned long nrValues = 0;
     unsigned long nrListElems = 0;
+    unsigned long nrLookups = 0;
     unsigned long nrAttrsets = 0;
     unsigned long nrAttrsInAttrsets = 0;
+    unsigned long nrAvoided = 0;
     unsigned long nrOpUpdates = 0;
     unsigned long nrOpUpdateValuesCopied = 0;
     unsigned long nrListConcats = 0;
@@ -339,6 +374,11 @@ private:
 
     friend struct ExprOpUpdate;
     friend struct ExprOpConcatLists;
+    friend struct ExprVar;
+    friend struct ExprString;
+    friend struct ExprInt;
+    friend struct ExprFloat;
+    friend struct ExprPath;
     friend struct ExprSelect;
     friend void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v);
     friend void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v);

src/libexpr/flake/config.cc

@@ -22,12 +22,14 @@ static TrustedList readTrustedList()
 
 static void writeTrustedList(const TrustedList & trustedList)
 {
-    writeFile(trustedListPath(), nlohmann::json(trustedList).dump());
+    auto path = trustedListPath();
+    createDirs(dirOf(path));
+    writeFile(path, nlohmann::json(trustedList).dump());
 }
 
 void ConfigFile::apply()
 {
-    std::set<std::string> whitelist{"bash-prompt", "bash-prompt-suffix"};
+    std::set<std::string> whitelist{"bash-prompt", "bash-prompt-suffix", "flake-registry"};
 
     for (auto & [name, value] : settings) {
 

src/libexpr/flake/flake.cc

@@ -1,4 +1,5 @@
 #include "flake.hh"
+#include "eval.hh"
 #include "lockfile.hh"
 #include "primops.hh"
 #include "eval-inline.hh"
@@ -63,8 +64,7 @@ static std::tuple<fetchers::Tree, FlakeRef, FlakeRef> fetchOrSubstituteTree(
     debug("got tree '%s' from '%s'",
         state.store->printStorePath(tree.storePath), lockedRef);
 
-    if (state.allowedPaths)
-        state.allowedPaths->insert(tree.actualPath);
+    state.allowPath(tree.storePath);
 
     assert(!originalRef.input.getNarHash() || tree.storePath == originalRef.input.computeStorePath(*state.store));
 
@@ -88,10 +88,12 @@ static void expectType(EvalState & state, ValueType type,
 }
 
 static std::map<FlakeId, FlakeInput> parseFlakeInputs(
-    EvalState & state, Value * value, const Pos & pos);
+    EvalState & state, Value * value, const Pos & pos,
+    const std::optional<Path> & baseDir);
 
 static FlakeInput parseFlakeInput(EvalState & state,
-    const std::string & inputName, Value * value, const Pos & pos)
+    const std::string & inputName, Value * value, const Pos & pos,
+    const std::optional<Path> & baseDir)
 {
     expectType(state, nAttrs, *value, pos);
 
@@ -115,7 +117,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
                 expectType(state, nBool, *attr.value, *attr.pos);
                 input.isFlake = attr.value->boolean;
             } else if (attr.name == sInputs) {
-                input.overrides = parseFlakeInputs(state, attr.value, *attr.pos);
+                input.overrides = parseFlakeInputs(state, attr.value, *attr.pos, baseDir);
             } else if (attr.name == sFollows) {
                 expectType(state, nString, *attr.value, *attr.pos);
                 input.follows = parseInputPath(attr.value->string.s);
@@ -153,7 +155,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
         if (!attrs.empty())
             throw Error("unexpected flake input attribute '%s', at %s", attrs.begin()->first, pos);
         if (url)
-            input.ref = parseFlakeRef(*url, {}, true);
+            input.ref = parseFlakeRef(*url, baseDir, true);
     }
 
     if (!input.follows && !input.ref)
@@ -163,7 +165,8 @@ static FlakeInput parseFlakeInput(EvalState & state,
 }
 
 static std::map<FlakeId, FlakeInput> parseFlakeInputs(
-    EvalState & state, Value * value, const Pos & pos)
+    EvalState & state, Value * value, const Pos & pos,
+    const std::optional<Path> & baseDir)
 {
     std::map<FlakeId, FlakeInput> inputs;
 
@@ -174,7 +177,8 @@ static std::map<FlakeId, FlakeInput> parseFlakeInputs(
             parseFlakeInput(state,
                 inputAttr.name,
                 inputAttr.value,
-                *inputAttr.pos));
+                *inputAttr.pos,
+                baseDir));
     }
 
     return inputs;
@@ -190,7 +194,8 @@ static Flake getFlake(
         state, originalRef, allowLookup, flakeCache);
 
     // Guard against symlink attacks.
-    auto flakeFile = canonPath(sourceInfo.actualPath + "/" + lockedRef.subdir + "/flake.nix");
+    auto flakeDir = canonPath(sourceInfo.actualPath + "/" + lockedRef.subdir);
+    auto flakeFile = canonPath(flakeDir + "/flake.nix");
     if (!isInDir(flakeFile, sourceInfo.actualPath))
         throw Error("'flake.nix' file of flake '%s' escapes from '%s'",
             lockedRef, state.store->printStorePath(sourceInfo.storePath));
@@ -218,14 +223,14 @@ static Flake getFlake(
     auto sInputs = state.symbols.create("inputs");
 
     if (auto inputs = vInfo.attrs->get(sInputs))
-        flake.inputs = parseFlakeInputs(state, inputs->value, *inputs->pos);
+        flake.inputs = parseFlakeInputs(state, inputs->value, *inputs->pos, flakeDir);
 
     auto sOutputs = state.symbols.create("outputs");
 
     if (auto outputs = vInfo.attrs->get(sOutputs)) {
         expectType(state, nFunction, *outputs->value, *outputs->pos);
 
-        if (outputs->value->isLambda() && outputs->value->lambda.fun->matchAttrs) {
+        if (outputs->value->isLambda() && outputs->value->lambda.fun->hasFormals()) {
             for (auto & formal : outputs->value->lambda.fun->formals->formals) {
                 if (formal.name != state.sSelf)
                     flake.inputs.emplace(formal.name, FlakeInput {
@@ -296,7 +301,14 @@ LockedFlake lockFlake(
 
     FlakeCache flakeCache;
 
-    auto flake = getFlake(state, topRef, lockFlags.useRegistries, flakeCache);
+    auto useRegistries = lockFlags.useRegistries.value_or(settings.useRegistries);
+
+    auto flake = getFlake(state, topRef, useRegistries, flakeCache);
+
+    if (lockFlags.applyNixConfig) {
+        flake.config.apply();
+        // FIXME: send new config to the daemon.
+    }
 
     try {
 
@@ -317,25 +329,38 @@ LockedFlake lockFlake(
 
         std::vector<FlakeRef> parents;
 
+        struct LockParent {
+            /* The path to this parent. */
+            InputPath path;
+
+            /* Whether we are currently inside a top-level lockfile
+               (inputs absolute) or subordinate lockfile (inputs
+               relative). */
+            bool absolute;
+        };
+
         std::function<void(
             const FlakeInputs & flakeInputs,
             std::shared_ptr<Node> node,
             const InputPath & inputPathPrefix,
-            std::shared_ptr<const Node> oldNode)>
+            std::shared_ptr<const Node> oldNode,
+            const LockParent & parent,
+            const Path & parentPath)>
             computeLocks;
 
         computeLocks = [&](
             const FlakeInputs & flakeInputs,
             std::shared_ptr<Node> node,
             const InputPath & inputPathPrefix,
-            std::shared_ptr<const Node> oldNode)
+            std::shared_ptr<const Node> oldNode,
+            const LockParent & parent,
+            const Path & parentPath)
         {
             debug("computing lock file node '%s'", printInputPath(inputPathPrefix));
 
             /* Get the overrides (i.e. attributes of the form
                'inputs.nixops.inputs.nixpkgs.url = ...'). */
-            // FIXME: check this
-            for (auto & [id, input] : flake.inputs) {
+            for (auto & [id, input] : flakeInputs) {
                 for (auto & [idOverride, inputOverride] : input.overrides) {
                     auto inputPath(inputPathPrefix);
                     inputPath.push_back(id);
@@ -359,22 +384,31 @@ LockedFlake lockFlake(
                        ancestors? */
                     auto i = overrides.find(inputPath);
                     bool hasOverride = i != overrides.end();
-                    if (hasOverride) overridesUsed.insert(inputPath);
+                    if (hasOverride) {
+                        overridesUsed.insert(inputPath);
+                        // Respect the “flakeness” of the input even if we
+                        // override it
+                        i->second.isFlake = input2.isFlake;
+                    }
                     auto & input = hasOverride ? i->second : input2;
 
                     /* Resolve 'follows' later (since it may refer to an input
                        path we haven't processed yet. */
                     if (input.follows) {
                         InputPath target;
-                        if (hasOverride || input.absolute)
-                            /* 'follows' from an override is relative to the
-                               root of the graph. */
+
+                        if (parent.absolute && !hasOverride) {
                             target = *input.follows;
-                        else {
-                            /* Otherwise, it's relative to the current flake. */
-                            target = inputPathPrefix;
+                        } else {
+                            if (hasOverride) {
+                                target = inputPathPrefix;
+                                target.pop_back();
+                            } else
+                                target = parent.path;
+
                             for (auto & i : *input.follows) target.push_back(i);
                         }
+
                         debug("input '%s' follows '%s'", inputPathS, printInputPath(target));
                         node->inputs.insert_or_assign(id, target);
                         continue;
@@ -420,7 +454,7 @@ LockedFlake lockFlake(
                         if (hasChildUpdate) {
                             auto inputFlake = getFlake(
                                 state, oldLock->lockedRef, false, flakeCache);
-                            computeLocks(inputFlake.inputs, childNode, inputPath, oldLock);
+                            computeLocks(inputFlake.inputs, childNode, inputPath, oldLock, parent, parentPath);
                         } else {
                             /* No need to fetch this flake, we can be
                                lazy. However there may be new overrides on the
@@ -437,12 +471,11 @@ LockedFlake lockFlake(
                                 } else if (auto follows = std::get_if<1>(&i.second)) {
                                     fakeInputs.emplace(i.first, FlakeInput {
                                         .follows = *follows,
-                                        .absolute = true
                                     });
                                 }
                             }
 
-                            computeLocks(fakeInputs, childNode, inputPath, oldLock);
+                            computeLocks(fakeInputs, childNode, inputPath, oldLock, parent, parentPath);
                         }
 
                     } else {
@@ -454,7 +487,15 @@ LockedFlake lockFlake(
                             throw Error("cannot update flake input '%s' in pure mode", inputPathS);
 
                         if (input.isFlake) {
-                            auto inputFlake = getFlake(state, *input.ref, lockFlags.useRegistries, flakeCache);
+                            Path localPath = parentPath;
+                            FlakeRef localRef = *input.ref;
+
+                            // If this input is a path, recurse it down.
+                            // This allows us to resolve path inputs relative to the current flake.
+                            if (localRef.input.getType() == "path")
+                                localPath = absPath(*input.ref->input.getSourcePath(), parentPath);
+
+                            auto inputFlake = getFlake(state, localRef, useRegistries, flakeCache);
 
                             /* Note: in case of an --override-input, we use
                                the *original* ref (input2.ref) for the
@@ -475,6 +516,13 @@ LockedFlake lockFlake(
                             parents.push_back(*input.ref);
                             Finally cleanup([&]() { parents.pop_back(); });
 
+                            // Follows paths from existing inputs in the top-level lockfile are absolute,
+                            // whereas paths in subordinate lockfiles are relative to those lockfiles.
+                            LockParent newParent {
+                                .path = inputPath,
+                                .absolute = oldLock ? true : false
+                            };
+
                             /* Recursively process the inputs of this
                                flake. Also, unless we already have this flake
                                in the top-level lock file, use this flake's
@@ -484,12 +532,13 @@ LockedFlake lockFlake(
                                 oldLock
                                 ? std::dynamic_pointer_cast<const Node>(oldLock)
                                 : LockFile::read(
-                                    inputFlake.sourceInfo->actualPath + "/" + inputFlake.lockedRef.subdir + "/flake.lock").root);
+                                    inputFlake.sourceInfo->actualPath + "/" + inputFlake.lockedRef.subdir + "/flake.lock").root,
+                                newParent, localPath);
                         }
 
                         else {
                             auto [sourceInfo, resolvedRef, lockedRef] = fetchOrSubstituteTree(
-                                state, *input.ref, lockFlags.useRegistries, flakeCache);
+                                state, *input.ref, useRegistries, flakeCache);
                             node->inputs.insert_or_assign(id,
                                 std::make_shared<LockedNode>(lockedRef, *input.ref, false));
                         }
@@ -502,9 +551,17 @@ LockedFlake lockFlake(
             }
         };
 
+        LockParent parent {
+            .path = {},
+            .absolute = true
+        };
+
+        // Bring in the current ref for relative path resolution if we have it
+        auto parentPath = canonPath(flake.sourceInfo->actualPath + "/" + flake.lockedRef.subdir);
+
         computeLocks(
             flake.inputs, newLockFile.root, {},
-            lockFlags.recreateLockFile ? nullptr : oldLockFile.root);
+            lockFlags.recreateLockFile ? nullptr : oldLockFile.root, parent, parentPath);
 
         for (auto & i : lockFlags.inputOverrides)
             if (!overridesUsed.count(i.first))
@@ -554,8 +611,8 @@ LockedFlake lockFlake(
                         topRef.input.markChangedFile(
                             (topRef.subdir == "" ? "" : topRef.subdir + "/") + "flake.lock",
                             lockFlags.commitLockFile
-                            ? std::optional<std::string>(fmt("%s: %s\n\nFlake input changes:\n\n%s",
-                                    relPath, lockFileExists ? "Update" : "Add", diff))
+                            ? std::optional<std::string>(fmt("%s: %s\n\nFlake lock file changes:\n\n%s",
+                                    relPath, lockFileExists ? "Update" : "Add", filterANSIEscapes(diff, true)))
                             : std::nullopt);
 
                         /* Rewriting the lockfile changed the top-level
@@ -563,7 +620,7 @@ LockedFlake lockFlake(
                            also just clear the 'rev' field... */
                         auto prevLockedRef = flake.lockedRef;
                         FlakeCache dummyCache;
-                        flake = getFlake(state, topRef, lockFlags.useRegistries, dummyCache);
+                        flake = getFlake(state, topRef, useRegistries, dummyCache);
 
                         if (lockFlags.commitLockFile &&
                             flake.lockedRef.input.getRev() &&
@@ -580,8 +637,10 @@ LockedFlake lockFlake(
                     }
                 } else
                     throw Error("cannot write modified lock file of flake '%s' (use '--no-write-lock-file' to ignore)", topRef);
-            } else
+            } else {
                 warn("not writing modified lock file of flake '%s':\n%s", topRef, chomp(diff));
+                flake.forceDirty = true;
+            }
         }
 
         return LockedFlake { .flake = std::move(flake), .lockFile = std::move(newLockFile) };
@@ -604,26 +663,32 @@ void callFlake(EvalState & state,
 
     mkString(*vLocks, lockedFlake.lockFile.to_string());
 
-    emitTreeAttrs(state, *lockedFlake.flake.sourceInfo, lockedFlake.flake.lockedRef.input, *vRootSrc);
+    emitTreeAttrs(
+        state,
+        *lockedFlake.flake.sourceInfo,
+        lockedFlake.flake.lockedRef.input,
+        *vRootSrc,
+        false,
+        lockedFlake.flake.forceDirty);
 
     mkString(*vRootSubdir, lockedFlake.flake.lockedRef.subdir);
 
-    static RootValue vCallFlake = nullptr;
-
-    if (!vCallFlake) {
-        vCallFlake = allocRootValue(state.allocValue());
+    if (!state.vCallFlake) {
+        state.vCallFlake = allocRootValue(state.allocValue());
         state.eval(state.parseExprFromString(
             #include "call-flake.nix.gen.hh"
-            , "/"), **vCallFlake);
+            , "/"), **state.vCallFlake);
     }
 
-    state.callFunction(**vCallFlake, *vLocks, *vTmp1, noPos);
+    state.callFunction(**state.vCallFlake, *vLocks, *vTmp1, noPos);
     state.callFunction(*vTmp1, *vRootSrc, *vTmp2, noPos);
     state.callFunction(*vTmp2, *vRootSubdir, vRes, noPos);
 }
 
 static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
+    state.requireExperimentalFeatureOnEvaluation("flakes", "builtins.getFlake", pos);
+
     auto flakeRefS = state.forceStringNoCtx(*args[0], pos);
     auto flakeRef = parseFlakeRef(flakeRefS, {}, true);
     if (evalSettings.pureEval && !flakeRef.input.isImmutable())
@@ -633,13 +698,13 @@ static void prim_getFlake(EvalState & state, const Pos & pos, Value * * args, Va
         lockFlake(state, flakeRef,
             LockFlags {
                 .updateLockFile = false,
-                .useRegistries = !evalSettings.pureEval,
+                .useRegistries = !evalSettings.pureEval && settings.useRegistries,
                 .allowMutable  = !evalSettings.pureEval,
             }),
         v);
 }
 
-static RegisterPrimOp r2("__getFlake", 1, prim_getFlake, "flakes");
+static RegisterPrimOp r2("__getFlake", 1, prim_getFlake);
 
 }
 
@@ -649,8 +714,9 @@ Fingerprint LockedFlake::getFingerprint() const
     // and we haven't changed it, then it's sufficient to use
     // flake.sourceInfo.storePath for the fingerprint.
     return hashString(htSHA256,
-        fmt("%s;%d;%d;%s",
+        fmt("%s;%s;%d;%d;%s",
             flake.sourceInfo->storePath.to_string(),
+            flake.lockedRef.subdir,
             flake.lockedRef.input.getRevCount().value_or(0),
             flake.lockedRef.input.getLastModified().value_or(0),
             lockFile));

src/libexpr/flake/flake.hh

@@ -43,7 +43,6 @@ struct FlakeInput
     std::optional<FlakeRef> ref;
     bool isFlake = true;  // true = process flake to get outputs, false = (fetched) static source path
     std::optional<InputPath> follows;
-    bool absolute = false; // whether 'follows' is relative to the flake root
     FlakeInputs overrides;
 };
 
@@ -59,9 +58,10 @@ struct ConfigFile
 /* The contents of a flake.nix file. */
 struct Flake
 {
-    FlakeRef originalRef;   // the original flake specification (by the user)
-    FlakeRef resolvedRef;   // registry references and caching resolved to the specific underlying flake
-    FlakeRef lockedRef;     // the specific local store result of invoking the fetcher
+    FlakeRef originalRef; // the original flake specification (by the user)
+    FlakeRef resolvedRef; // registry references and caching resolved to the specific underlying flake
+    FlakeRef lockedRef; // the specific local store result of invoking the fetcher
+    bool forceDirty = false; // pretend that 'lockedRef' is dirty
     std::optional<std::string> description;
     std::shared_ptr<const fetchers::Tree> sourceInfo;
     FlakeInputs inputs;
@@ -102,7 +102,11 @@ struct LockFlags
 
     /* Whether to use the registries to lookup indirect flake
        references like 'nixpkgs'. */
-    bool useRegistries = true;
+    std::optional<bool> useRegistries = std::nullopt;
+
+    /* Whether to apply flake's nixConfig attribute to the configuration */
+
+    bool applyNixConfig = false;
 
     /* Whether mutable flake references (i.e. those without a Git
        revision or similar) without a corresponding lock are
@@ -113,7 +117,7 @@ struct LockFlags
     /* Whether to commit changes to flake.lock. */
     bool commitLockFile = false;
 
-    /* Flake inputs to be overriden. */
+    /* Flake inputs to be overridden. */
     std::map<InputPath, FlakeRef> inputOverrides;
 
     /* Flake inputs to be updated. This means that any existing lock
@@ -137,6 +141,8 @@ void emitTreeAttrs(
     EvalState & state,
     const fetchers::Tree & tree,
     const fetchers::Input & input,
-    Value & v, bool emptyRevFallback = false);
+    Value & v,
+    bool emptyRevFallback = false,
+    bool forceDirty = false);
 
 }

src/libexpr/flake/flakeref.cc

@@ -172,8 +172,12 @@ std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
         auto parsedURL = parseURL(url);
         std::string fragment;
         std::swap(fragment, parsedURL.fragment);
+
+        auto input = Input::fromURL(parsedURL);
+        input.parent = baseDir;
+
         return std::make_pair(
-            FlakeRef(Input::fromURL(parsedURL), get(parsedURL.query, "dir").value_or("")),
+            FlakeRef(std::move(input), get(parsedURL.query, "dir").value_or("")),
             fragment);
     }
 }

src/libexpr/flake/lockfile.cc

@@ -2,6 +2,8 @@
 #include "store-api.hh"
 #include "url-parts.hh"
 
+#include <iomanip>
+
 #include <nlohmann/json.hpp>
 
 namespace nix::flake {
@@ -268,10 +270,20 @@ std::map<InputPath, Node::Edge> LockFile::getAllInputs() const
     return res;
 }
 
+static std::string describe(const FlakeRef & flakeRef)
+{
+    auto s = fmt("'%s'", flakeRef.to_string());
+
+    if (auto lastModified = flakeRef.input.getLastModified())
+        s += fmt(" (%s)", std::put_time(std::gmtime(&*lastModified), "%Y-%m-%d"));
+
+    return s;
+}
+
 std::ostream & operator <<(std::ostream & stream, const Node::Edge & edge)
 {
     if (auto node = std::get_if<0>(&edge))
-        stream << "'" << (*node)->lockedRef << "'";
+        stream << describe((*node)->lockedRef);
     else if (auto follows = std::get_if<1>(&edge))
         stream << fmt("follows '%s'", printInputPath(*follows));
     return stream;
@@ -299,14 +311,15 @@ std::string LockFile::diff(const LockFile & oldLocks, const LockFile & newLocks)
 
     while (i != oldFlat.end() || j != newFlat.end()) {
         if (j != newFlat.end() && (i == oldFlat.end() || i->first > j->first)) {
-            res += fmt("* Added '%s': %s\n", printInputPath(j->first), j->second);
+            res += fmt("• " ANSI_GREEN "Added input '%s':" ANSI_NORMAL "\n    %s\n",
+                printInputPath(j->first), j->second);
             ++j;
         } else if (i != oldFlat.end() && (j == newFlat.end() || i->first < j->first)) {
-            res += fmt("* Removed '%s'\n", printInputPath(i->first));
+            res += fmt("• " ANSI_RED "Removed input '%s'" ANSI_NORMAL "\n", printInputPath(i->first));
             ++i;
         } else {
             if (!equals(i->second, j->second)) {
-                res += fmt("* Updated '%s': %s -> %s\n",
+                res += fmt("• " ANSI_BOLD "Updated input '%s':" ANSI_NORMAL "\n    %s\n  → %s\n",
                     printInputPath(i->first),
                     i->second,
                     j->second);

src/libexpr/get-drvs.cc

@@ -2,6 +2,7 @@
 #include "util.hh"
 #include "eval-inline.hh"
 #include "store-api.hh"
+#include "path-with-outputs.hh"
 
 #include <cstring>
 #include <regex>
@@ -19,7 +20,7 @@ DrvInfo::DrvInfo(EvalState & state, const string & attrPath, Bindings * attrs)
 DrvInfo::DrvInfo(EvalState & state, ref<Store> store, const std::string & drvPathWithOutputs)
     : state(&state), attrs(nullptr), attrPath("")
 {
-    auto [drvPath, selectedOutputs] = store->parsePathWithOutputs(drvPathWithOutputs);
+    auto [drvPath, selectedOutputs] = parsePathWithOutputs(*store, drvPathWithOutputs);
 
     this->drvPath = store->printStorePath(drvPath);
 

src/libexpr/lexer.l

@@ -9,6 +9,9 @@
 %s DEFAULT
 %x STRING
 %x IND_STRING
+%x INPATH
+%x INPATH_SLASH
+%x PATH_START
 
 
 %{
@@ -25,6 +28,8 @@ using namespace nix;
 
 namespace nix {
 
+// backup to recover from yyless(0)
+YYLTYPE prev_yylloc;
 
 static void initLoc(YYLTYPE * loc)
 {
@@ -35,14 +40,18 @@ static void initLoc(YYLTYPE * loc)
 
 static void adjustLoc(YYLTYPE * loc, const char * s, size_t len)
 {
+    prev_yylloc = *loc;
+
     loc->first_line = loc->last_line;
     loc->first_column = loc->last_column;
 
-    while (len--) {
+    for (size_t i = 0; i < len; i++) {
        switch (*s++) {
        case '\r':
-           if (*s == '\n') /* cr/lf */
+           if (*s == '\n') { /* cr/lf */
+               i++;
                s++;
+           }
            /* fall through */
        case '\n':
            ++loc->last_line;
@@ -95,9 +104,12 @@ ANY         .|\n
 ID          [a-zA-Z\_][a-zA-Z0-9\_\'\-]*
 INT         [0-9]+
 FLOAT       (([1-9][0-9]*\.[0-9]*)|(0?\.[0-9]+))([Ee][+-]?[0-9]+)?
-PATH        [a-zA-Z0-9\.\_\-\+]*(\/[a-zA-Z0-9\.\_\-\+]+)+\/?
-HPATH       \~(\/[a-zA-Z0-9\.\_\-\+]+)+\/?
-SPATH       \<[a-zA-Z0-9\.\_\-\+]+(\/[a-zA-Z0-9\.\_\-\+]+)*\>
+PATH_CHAR   [a-zA-Z0-9\.\_\-\+]
+PATH        {PATH_CHAR}*(\/{PATH_CHAR}+)+\/?
+PATH_SEG    {PATH_CHAR}*\/
+HPATH       \~(\/{PATH_CHAR}+)+\/?
+HPATH_START \~\/
+SPATH       \<{PATH_CHAR}+(\/{PATH_CHAR}+)*\>
 URI         [a-zA-Z][a-zA-Z0-9\+\-\.]*\:[a-zA-Z0-9\%\/\?\:\@\&\=\+\$\,\-\_\.\!\~\*\']+
 
 
@@ -198,17 +210,75 @@ or          { return OR_KW; }
                    return IND_STR;
                  }
 
+{PATH_SEG}\$\{ |
+{HPATH_START}\$\{ {
+  PUSH_STATE(PATH_START);
+  yyless(0);
+  *yylloc = prev_yylloc;
+}
+
+<PATH_START>{PATH_SEG} {
+  POP_STATE();
+  PUSH_STATE(INPATH_SLASH);
+  yylval->path = strdup(yytext);
+  return PATH;
+}
+
+<PATH_START>{HPATH_START} {
+  POP_STATE();
+  PUSH_STATE(INPATH_SLASH);
+  yylval->path = strdup(yytext);
+  return HPATH;
+}
+
+{PATH} {
+  if (yytext[yyleng-1] == '/')
+    PUSH_STATE(INPATH_SLASH);
+  else
+    PUSH_STATE(INPATH);
+  yylval->path = strdup(yytext);
+  return PATH;
+}
+{HPATH} {
+  if (yytext[yyleng-1] == '/')
+    PUSH_STATE(INPATH_SLASH);
+  else
+    PUSH_STATE(INPATH);
+  yylval->path = strdup(yytext);
+  return HPATH;
+}
+
+<INPATH,INPATH_SLASH>\$\{ {
+  POP_STATE();
+  PUSH_STATE(INPATH);
+  PUSH_STATE(DEFAULT);
+  return DOLLAR_CURLY;
+}
+<INPATH,INPATH_SLASH>{PATH}|{PATH_SEG}|{PATH_CHAR}+ {
+  POP_STATE();
+  if (yytext[yyleng-1] == '/')
+      PUSH_STATE(INPATH_SLASH);
+  else
+      PUSH_STATE(INPATH);
+  yylval->e = new ExprString(data->symbols.create(string(yytext)));
+  return STR;
+}
+<INPATH>{ANY} |
+<INPATH><<EOF>> {
+  /* if we encounter a non-path character we inform the parser that the path has
+     ended with a PATH_END token and re-parse this character in the default
+     context (it may be ')', ';', or something of that sort) */
+  POP_STATE();
+  yyless(0);
+  *yylloc = prev_yylloc;
+  return PATH_END;
+}
+
+<INPATH_SLASH>{ANY} |
+<INPATH_SLASH><<EOF>> {
+  throw ParseError("path has a trailing slash");
+}
 
-{PATH}      { if (yytext[yyleng-1] == '/')
-                  throw ParseError("path '%s' has a trailing slash", yytext);
-              yylval->path = strdup(yytext);
-              return PATH;
-            }
-{HPATH}     { if (yytext[yyleng-1] == '/')
-                  throw ParseError("path '%s' has a trailing slash", yytext);
-              yylval->path = strdup(yytext);
-              return HPATH;
-            }
 {SPATH}     { yylval->path = strdup(yytext); return SPATH; }
 {URI}       { yylval->uri = strdup(yytext); return URI; }
 

src/libexpr/local.mk

@@ -15,8 +15,8 @@ libexpr_CXXFLAGS += -I src/libutil -I src/libstore -I src/libfetchers -I src/lib
 
 libexpr_LIBS = libutil libstore libfetchers
 
-libexpr_LDFLAGS = -lboost_context
-ifneq ($(OS), FreeBSD)
+libexpr_LDFLAGS += -lboost_context -pthread
+ifdef HOST_LINUX
  libexpr_LDFLAGS += -ldl
 endif
 
@@ -35,7 +35,7 @@ $(d)/lexer-tab.cc $(d)/lexer-tab.hh: $(d)/lexer.l
 
 clean-files += $(d)/parser-tab.cc $(d)/parser-tab.hh $(d)/lexer-tab.cc $(d)/lexer-tab.hh
 
-$(eval $(call install-file-in, $(d)/nix-expr.pc, $(prefix)/lib/pkgconfig, 0644))
+$(eval $(call install-file-in, $(d)/nix-expr.pc, $(libdir)/pkgconfig, 0644))
 
 $(foreach i, $(wildcard src/libexpr/flake/*.hh), \
   $(eval $(call install-file-in, $(i), $(includedir)/nix/flake, 0644)))

src/libexpr/nixexpr.cc

@@ -124,7 +124,7 @@ void ExprList::show(std::ostream & str) const
 void ExprLambda::show(std::ostream & str) const
 {
     str << "(";
-    if (matchAttrs) {
+    if (hasFormals()) {
         str << "{ ";
         bool first = true;
         for (auto & i : formals->formals) {
@@ -348,7 +348,7 @@ void ExprLambda::bindVars(const StaticEnv & env)
 
     if (!arg.empty()) newEnv.vars[arg] = displ++;
 
-    if (matchAttrs) {
+    if (hasFormals()) {
         for (auto & i : formals->formals)
             newEnv.vars[i.name] = displ++;
 

src/libexpr/nixexpr.hh

@@ -17,7 +17,7 @@ MakeError(ThrownError, AssertionError);
 MakeError(Abort, EvalError);
 MakeError(TypeError, EvalError);
 MakeError(UndefinedVarError, Error);
-MakeError(MissingArgumentError, Error);
+MakeError(MissingArgumentError, EvalError);
 MakeError(RestrictedPathError, Error);
 
 
@@ -180,6 +180,7 @@ struct ExprOpHasAttr : Expr
 struct ExprAttrs : Expr
 {
     bool recursive;
+    Pos pos;
     struct AttrDef {
         bool inherited;
         Expr * e;
@@ -199,7 +200,8 @@ struct ExprAttrs : Expr
     };
     typedef std::vector<DynamicAttrDef> DynamicAttrDefs;
     DynamicAttrDefs dynamicAttrs;
-    ExprAttrs() : recursive(false) { };
+    ExprAttrs(const Pos &pos) : recursive(false), pos(pos) { };
+    ExprAttrs() : recursive(false), pos(noPos) { };
     COMMON_METHODS
 };
 
@@ -231,11 +233,10 @@ struct ExprLambda : Expr
     Pos pos;
     Symbol name;
     Symbol arg;
-    bool matchAttrs;
     Formals * formals;
     Expr * body;
-    ExprLambda(const Pos & pos, const Symbol & arg, bool matchAttrs, Formals * formals, Expr * body)
-        : pos(pos), arg(arg), matchAttrs(matchAttrs), formals(formals), body(body)
+    ExprLambda(const Pos & pos, const Symbol & arg, Formals * formals, Expr * body)
+        : pos(pos), arg(arg), formals(formals), body(body)
     {
         if (!arg.empty() && formals && formals->argNames.find(arg) != formals->argNames.end())
             throw ParseError({
@@ -245,6 +246,7 @@ struct ExprLambda : Expr
     };
     void setName(Symbol & name);
     string showNamePos() const;
+    inline bool hasFormals() const { return formals != nullptr; }
     COMMON_METHODS
 };
 

src/libexpr/parser.y

@@ -290,13 +290,13 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
 %type <formal> formal
 %type <attrNames> attrs attrpath
 %type <string_parts> string_parts_interpolated ind_string_parts
-%type <e> string_parts string_attr
+%type <e> path_start string_parts string_attr
 %type <id> attr
 %token <id> ID ATTRPATH
 %token <e> STR IND_STR
 %token <n> INT
 %token <nf> FLOAT
-%token <path> PATH HPATH SPATH
+%token <path> PATH HPATH SPATH PATH_END
 %token <uri> URI
 %token IF THEN ELSE ASSERT WITH LET IN REC INHERIT EQ NEQ AND OR IMPL OR_KW
 %token DOLLAR_CURLY /* == ${ */
@@ -324,13 +324,13 @@ expr: expr_function;
 
 expr_function
   : ID ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), false, 0, $3); }
+    { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), 0, $3); }
   | '{' formals '}' ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create(""), true, $2, $5); }
+    { $$ = new ExprLambda(CUR_POS, data->symbols.create(""), $2, $5); }
   | '{' formals '}' '@' ID ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create($5), true, $2, $7); }
+    { $$ = new ExprLambda(CUR_POS, data->symbols.create($5), $2, $7); }
   | ID '@' '{' formals '}' ':' expr_function
-    { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), true, $4, $7); }
+    { $$ = new ExprLambda(CUR_POS, data->symbols.create($1), $4, $7); }
   | ASSERT expr ';' expr_function
     { $$ = new ExprAssert(CUR_POS, $2, $4); }
   | WITH expr ';' expr_function
@@ -405,8 +405,11 @@ expr_simple
   | IND_STRING_OPEN ind_string_parts IND_STRING_CLOSE {
       $$ = stripIndentation(CUR_POS, data->symbols, *$2);
   }
-  | PATH { $$ = new ExprPath(absPath($1, data->basePath)); }
-  | HPATH { $$ = new ExprPath(getHome() + string{$1 + 1}); }
+  | path_start PATH_END { $$ = $1; }
+  | path_start string_parts_interpolated PATH_END {
+      $2->insert($2->begin(), $1);
+      $$ = new ExprConcatStrings(CUR_POS, false, $2);
+  }
   | SPATH {
       string path($1 + 1, strlen($1) - 2);
       $$ = new ExprApp(CUR_POS,
@@ -452,6 +455,20 @@ string_parts_interpolated
     }
   ;
 
+path_start
+  : PATH {
+    Path path(absPath($1, data->basePath));
+    /* add back in the trailing '/' to the first segment */
+    if ($1[strlen($1)-1] == '/' && strlen($1) > 1)
+      path += "/";
+    $$ = new ExprPath(path);
+  }
+  | HPATH {
+    Path path(getHome() + string($1 + 1));
+    $$ = new ExprPath(path);
+  }
+  ;
+
 ind_string_parts
   : ind_string_parts IND_STR { $$ = $1; $1->push_back($2); }
   | ind_string_parts DOLLAR_CURLY expr '}' { $$ = $1; $1->push_back($3); }
@@ -478,7 +495,7 @@ binds
           $$->attrs[i.symbol] = ExprAttrs::AttrDef(new ExprSelect(CUR_POS, $4, i.symbol), makeCurPos(@6, data));
       }
     }
-  | { $$ = new ExprAttrs; }
+  | { $$ = new ExprAttrs(makeCurPos(@0, data)); }
   ;
 
 attrs
@@ -735,7 +752,7 @@ std::pair<bool, std::string> EvalState::resolveSearchPathElem(const SearchPathEl
             res = { true, path };
         else {
             logWarning({
-                .msg = hintfmt("warning: Nix search path entry '%1%' does not exist, ignoring", elem.second)
+                .msg = hintfmt("Nix search path entry '%1%' does not exist, ignoring", elem.second)
             });
             res = { false, "" };
         }

src/libexpr/primops.cc

@@ -21,6 +21,8 @@
 #include <regex>
 #include <dlfcn.h>
 
+#include <cmath>
+
 
 namespace nix {
 
@@ -35,7 +37,7 @@ InvalidPathError::InvalidPathError(const Path & path) :
 
 void EvalState::realiseContext(const PathSet & context)
 {
-    std::vector<StorePathWithOutputs> drvs;
+    std::vector<DerivedPath::Built> drvs;
 
     for (auto & i : context) {
         auto [ctxS, outputName] = decodeContext(i);
@@ -43,22 +45,21 @@ void EvalState::realiseContext(const PathSet & context)
         if (!store->isValidPath(ctx))
             throw InvalidPathError(store->printStorePath(ctx));
         if (!outputName.empty() && ctx.isDerivation()) {
-            drvs.push_back(StorePathWithOutputs{ctx, {outputName}});
+            drvs.push_back({ctx, {outputName}});
         }
     }
 
     if (drvs.empty()) return;
 
     if (!evalSettings.enableImportFromDerivation)
-        throw EvalError("attempted to realize '%1%' during evaluation but 'allow-import-from-derivation' is false",
-            store->printStorePath(drvs.begin()->path));
+        throw Error(
+            "cannot build '%1%' during evaluation because the option 'allow-import-from-derivation' is disabled",
+            store->printStorePath(drvs.begin()->drvPath));
 
-    /* For performance, prefetch all substitute info. */
-    StorePathSet willBuild, willSubstitute, unknown;
-    uint64_t downloadSize, narSize;
-    store->queryMissing(drvs, willBuild, willSubstitute, unknown, downloadSize, narSize);
-
-    store->buildPaths(drvs);
+    /* Build/substitute the context. */
+    std::vector<DerivedPath> buildReqs;
+    for (auto & d : drvs) buildReqs.emplace_back(DerivedPath { d });
+    store->buildPaths(buildReqs);
 
     /* Add the output of this derivations to the allowed
        paths. */
@@ -120,7 +121,7 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
         });
     } catch (Error & e) {
         e.addTrace(pos, "while importing '%s'", path);
-        throw e;
+        throw;
     }
 
     Path realPath = state.checkSourcePath(state.toRealPath(path, context));
@@ -156,16 +157,15 @@ static void import(EvalState & state, const Pos & pos, Value & vPath, Value * vS
         }
         w.attrs->sort();
 
-        static RootValue fun;
-        if (!fun) {
-            fun = allocRootValue(state.allocValue());
+        if (!state.vImportedDrvToDerivation) {
+            state.vImportedDrvToDerivation = allocRootValue(state.allocValue());
             state.eval(state.parseExprFromString(
                 #include "imported-drv-to-derivation.nix.gen.hh"
-                , "/"), **fun);
+                , "/"), **state.vImportedDrvToDerivation);
         }
 
-        state.forceFunction(**fun, pos);
-        mkApp(v, **fun, w);
+        state.forceFunction(**state.vImportedDrvToDerivation, pos);
+        mkApp(v, **state.vImportedDrvToDerivation, w);
         state.forceAttrs(v, pos);
     }
 
@@ -410,7 +410,7 @@ static RegisterPrimOp primop_isNull({
       Return `true` if *e* evaluates to `null`, and `false` otherwise.
 
       > **Warning**
-      > 
+      >
       > This function is *deprecated*; just write `e == null` instead.
     )",
     .fun = prim_isNull,
@@ -545,18 +545,56 @@ typedef list<Value *> ValueList;
 #endif
 
 
+static Bindings::iterator getAttr(
+    EvalState & state,
+    string funcName,
+    string attrName,
+    Bindings * attrSet,
+    const Pos & pos)
+{
+    Bindings::iterator value = attrSet->find(state.symbols.create(attrName));
+    if (value == attrSet->end()) {
+        hintformat errorMsg = hintfmt(
+            "attribute '%s' missing for call to '%s'",
+            attrName,
+            funcName
+        );
+
+        Pos aPos = *attrSet->pos;
+        if (aPos == noPos) {
+            throw TypeError({
+                .msg = errorMsg,
+                .errPos = pos,
+            });
+        } else {
+            auto e = TypeError({
+                .msg = errorMsg,
+                .errPos = aPos,
+            });
+
+            // Adding another trace for the function name to make it clear
+            // which call received wrong arguments.
+            e.addTrace(pos, hintfmt("while invoking '%s'", funcName));
+            throw e;
+        }
+    }
+
+    return value;
+}
+
 static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     state.forceAttrs(*args[0], pos);
 
     /* Get the start set. */
-    Bindings::iterator startSet =
-        args[0]->attrs->find(state.symbols.create("startSet"));
-    if (startSet == args[0]->attrs->end())
-        throw EvalError({
-            .msg = hintfmt("attribute 'startSet' required"),
-            .errPos = pos
-        });
+    Bindings::iterator startSet = getAttr(
+        state,
+        "genericClosure",
+        "startSet",
+        args[0]->attrs,
+        pos
+    );
+
     state.forceList(*startSet->value, pos);
 
     ValueList workSet;
@@ -564,13 +602,14 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
         workSet.push_back(startSet->value->listElems()[n]);
 
     /* Get the operator. */
-    Bindings::iterator op =
-        args[0]->attrs->find(state.symbols.create("operator"));
-    if (op == args[0]->attrs->end())
-        throw EvalError({
-            .msg = hintfmt("attribute 'operator' required"),
-            .errPos = pos
-        });
+    Bindings::iterator op = getAttr(
+        state,
+        "genericClosure",
+        "operator",
+        args[0]->attrs,
+        pos
+    );
+
     state.forceValue(*op->value, pos);
 
     /* Construct the closure by applying the operator to element of
@@ -673,6 +712,44 @@ static RegisterPrimOp primop_addErrorContext(RegisterPrimOp::Info {
     .fun = prim_addErrorContext,
 });
 
+static void prim_ceil(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    auto value = state.forceFloat(*args[0], args[0]->determinePos(pos));
+    mkInt(v, ceil(value));
+}
+
+static RegisterPrimOp primop_ceil({
+    .name = "__ceil",
+    .args = {"double"},
+    .doc = R"(
+        Converts an IEEE-754 double-precision floating-point number (*double*) to
+        the next higher integer.
+
+        If the datatype is neither an integer nor a "float", an evaluation error will be
+        thrown.
+    )",
+    .fun = prim_ceil,
+});
+
+static void prim_floor(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    auto value = state.forceFloat(*args[0], args[0]->determinePos(pos));
+    mkInt(v, floor(value));
+}
+
+static RegisterPrimOp primop_floor({
+    .name = "__floor",
+    .args = {"double"},
+    .doc = R"(
+        Converts an IEEE-754 double-precision floating-point number (*double*) to
+        the next lower integer.
+
+        If the datatype is neither an integer nor a "float", an evaluation error will be
+        thrown.
+    )",
+    .fun = prim_floor,
+});
+
 /* Try evaluating the argument. Success => {success=true; value=something;},
  * else => {success=false; value=false;} */
 static void prim_tryEval(EvalState & state, const Pos & pos, Value * * args, Value & v)
@@ -814,12 +891,14 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
     state.forceAttrs(*args[0], pos);
 
     /* Figure out the name first (for stack backtraces). */
-    Bindings::iterator attr = args[0]->attrs->find(state.sName);
-    if (attr == args[0]->attrs->end())
-        throw EvalError({
-            .msg = hintfmt("required attribute 'name' missing"),
-            .errPos = pos
-        });
+    Bindings::iterator attr = getAttr(
+        state,
+        "derivationStrict",
+        state.sName,
+        args[0]->attrs,
+        pos
+    );
+
     string drvName;
     Pos & posDrvName(*attr->pos);
     try {
@@ -951,7 +1030,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                     }
 
                 } else {
-                    auto s = state.coerceToString(posDrvName, *i->value, context, true);
+                    auto s = state.coerceToString(*i->pos, *i->value, context, true);
                     drv.env.emplace(key, s);
                     if (i->name == state.sBuilder) drv.builder = s;
                     else if (i->name == state.sSystem) drv.platform = s;
@@ -1091,7 +1170,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
         // hash per output.
         auto hashModulo = hashDerivationModulo(*state.store, Derivation(drv), true);
         std::visit(overloaded {
-            [&](Hash h) {
+            [&](Hash & h) {
                 for (auto & i : outputs) {
                     auto outPath = state.store->makeOutputPath(i, h, drvName);
                     drv.env[i] = state.store->printStorePath(outPath);
@@ -1103,11 +1182,11 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                         });
                 }
             },
-            [&](CaOutputHashes) {
+            [&](CaOutputHashes &) {
                 // Shouldn't happen as the toplevel derivation is not CA.
                 assert(false);
             },
-            [&](DeferredHash _) {
+            [&](DeferredHash &) {
                 for (auto & i : outputs) {
                     drv.outputs.insert_or_assign(i,
                         DerivationOutput {
@@ -1208,7 +1287,10 @@ static RegisterPrimOp primop_toPath({
 static void prim_storePath(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
     if (evalSettings.pureEval)
-        throw EvalError("builtins.storePath' is not allowed in pure evaluation mode");
+        throw EvalError({
+            .msg = hintfmt("'%s' is not allowed in pure evaluation mode", "builtins.storePath"),
+            .errPos = pos
+        });
 
     PathSet context;
     Path path = state.checkSourcePath(state.coerceToPath(pos, *args[0], context));
@@ -1367,12 +1449,13 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
         if (i != v2.attrs->end())
             prefix = state.forceStringNoCtx(*i->value, pos);
 
-        i = v2.attrs->find(state.symbols.create("path"));
-        if (i == v2.attrs->end())
-            throw EvalError({
-                .msg = hintfmt("attribute 'path' missing"),
-                .errPos = pos
-            });
+        i = getAttr(
+            state,
+            "findFile",
+            "path",
+            v2.attrs,
+            pos
+        );
 
         PathSet context;
         string path = state.coerceToString(pos, *i->value, context, false, false);
@@ -1406,15 +1489,20 @@ static void prim_hashFile(EvalState & state, const Pos & pos, Value * * args, Va
     string type = state.forceStringNoCtx(*args[0], pos);
     std::optional<HashType> ht = parseHashType(type);
     if (!ht)
-      throw Error({
-          .msg = hintfmt("unknown hash type '%1%'", type),
-          .errPos = pos
-      });
+        throw Error({
+            .msg = hintfmt("unknown hash type '%1%'", type),
+            .errPos = pos
+        });
 
-    PathSet context; // discarded
-    Path p = state.coerceToPath(pos, *args[1], context);
+    PathSet context;
+    Path path = state.coerceToPath(pos, *args[1], context);
+    try {
+        state.realiseContext(context);
+    } catch (InvalidPathError & e) {
+        throw EvalError("cannot read '%s' since path '%s' is not valid, at %s", path, e.path, pos);
+    }
 
-    mkString(v, hashFile(*ht, state.checkSourcePath(p)).to_string(Base16, false), context);
+    mkString(v, hashFile(*ht, state.checkSourcePath(state.toRealPath(path, context))).to_string(Base16, false));
 }
 
 static RegisterPrimOp primop_hashFile({
@@ -1625,7 +1713,7 @@ static void prim_fromJSON(EvalState & state, const Pos & pos, Value * * args, Va
         parseJSON(state, s, v);
     } catch (JSONParseError &e) {
         e.addTrace(pos, "while decoding a JSON string");
-        throw e;
+        throw;
     }
 }
 
@@ -1755,50 +1843,81 @@ static RegisterPrimOp primop_toFile({
     .fun = prim_toFile,
 });
 
-static void addPath(EvalState & state, const Pos & pos, const string & name, const Path & path_,
-    Value * filterFun, FileIngestionMethod method, const std::optional<Hash> expectedHash, Value & v)
+static void addPath(
+    EvalState & state,
+    const Pos & pos,
+    const string & name,
+    Path path,
+    Value * filterFun,
+    FileIngestionMethod method,
+    const std::optional<Hash> expectedHash,
+    Value & v,
+    const PathSet & context)
 {
-    const auto path = evalSettings.pureEval && expectedHash ?
-        path_ :
-        state.checkSourcePath(path_);
-    PathFilter filter = filterFun ? ([&](const Path & path) {
-        auto st = lstat(path);
+    try {
+        // FIXME: handle CA derivation outputs (where path needs to
+        // be rewritten to the actual output).
+        state.realiseContext(context);
 
-        /* Call the filter function.  The first argument is the path,
-           the second is a string indicating the type of the file. */
-        Value arg1;
-        mkString(arg1, path);
+        if (state.store->isInStore(path)) {
+            auto [storePath, subPath] = state.store->toStorePath(path);
+            auto info = state.store->queryPathInfo(storePath);
+            if (!info->references.empty())
+                throw EvalError("store path '%s' is not allowed to have references",
+                    state.store->printStorePath(storePath));
+            path = state.store->toRealPath(storePath) + subPath;
+        }
 
-        Value fun2;
-        state.callFunction(*filterFun, arg1, fun2, noPos);
+        path = evalSettings.pureEval && expectedHash
+            ? path
+            : state.checkSourcePath(path);
 
-        Value arg2;
-        mkString(arg2,
-            S_ISREG(st.st_mode) ? "regular" :
-            S_ISDIR(st.st_mode) ? "directory" :
-            S_ISLNK(st.st_mode) ? "symlink" :
-            "unknown" /* not supported, will fail! */);
+        PathFilter filter = filterFun ? ([&](const Path & path) {
+            auto st = lstat(path);
 
-        Value res;
-        state.callFunction(fun2, arg2, res, noPos);
+            /* Call the filter function.  The first argument is the path,
+               the second is a string indicating the type of the file. */
+            Value arg1;
+            mkString(arg1, path);
 
-        return state.forceBool(res, pos);
-    }) : defaultPathFilter;
+            Value fun2;
+            state.callFunction(*filterFun, arg1, fun2, noPos);
 
-    std::optional<StorePath> expectedStorePath;
-    if (expectedHash)
-        expectedStorePath = state.store->makeFixedOutputPath(method, *expectedHash, name);
-    Path dstPath;
-    if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
-        dstPath = state.store->printStorePath(settings.readOnlyMode
-            ? state.store->computeStorePathForPath(name, path, method, htSHA256, filter).first
-            : state.store->addToStore(name, path, method, htSHA256, filter, state.repair));
-        if (expectedHash && expectedStorePath != state.store->parseStorePath(dstPath))
-            throw Error("store path mismatch in (possibly filtered) path added from '%s'", path);
-    } else
-        dstPath = state.store->printStorePath(*expectedStorePath);
+            Value arg2;
+            mkString(arg2,
+                S_ISREG(st.st_mode) ? "regular" :
+                S_ISDIR(st.st_mode) ? "directory" :
+                S_ISLNK(st.st_mode) ? "symlink" :
+                "unknown" /* not supported, will fail! */);
 
-    mkString(v, dstPath, {dstPath});
+            Value res;
+            state.callFunction(fun2, arg2, res, noPos);
+
+            return state.forceBool(res, pos);
+        }) : defaultPathFilter;
+
+        std::optional<StorePath> expectedStorePath;
+        if (expectedHash)
+            expectedStorePath = state.store->makeFixedOutputPath(method, *expectedHash, name);
+
+        Path dstPath;
+        if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
+            dstPath = state.store->printStorePath(settings.readOnlyMode
+                ? state.store->computeStorePathForPath(name, path, method, htSHA256, filter).first
+                : state.store->addToStore(name, path, method, htSHA256, filter, state.repair));
+            if (expectedHash && expectedStorePath != state.store->parseStorePath(dstPath))
+                throw Error("store path mismatch in (possibly filtered) path added from '%s'", path);
+        } else
+            dstPath = state.store->printStorePath(*expectedStorePath);
+
+        mkString(v, dstPath, {dstPath});
+
+        state.allowPath(dstPath);
+
+    } catch (Error & e) {
+        e.addTrace(pos, "while adding path '%s'", path);
+        throw;
+    }
 }
 
 
@@ -1806,11 +1925,6 @@ static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args
 {
     PathSet context;
     Path path = state.coerceToPath(pos, *args[1], context);
-    if (!context.empty())
-        throw EvalError({
-            .msg = hintfmt("string '%1%' cannot refer to other paths", path),
-            .errPos = pos
-        });
 
     state.forceValue(*args[0], pos);
     if (args[0]->type() != nFunction)
@@ -1821,13 +1935,26 @@ static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args
             .errPos = pos
         });
 
-    addPath(state, pos, std::string(baseNameOf(path)), path, args[0], FileIngestionMethod::Recursive, std::nullopt, v);
+    addPath(state, pos, std::string(baseNameOf(path)), path, args[0], FileIngestionMethod::Recursive, std::nullopt, v, context);
 }
 
 static RegisterPrimOp primop_filterSource({
     .name = "__filterSource",
     .args = {"e1", "e2"},
     .doc = R"(
+      > **Warning**
+      >
+      > `filterSource` should not be used to filter store paths. Since
+      > `filterSource` uses the name of the input directory while naming
+      > the output directory, doing so will produce a directory name in
+      > the form of `<hash2>-<hash>-<name>`, where `<hash>-<name>` is
+      > the name of the input directory. Since `<hash>` depends on the
+      > unfiltered directory, the name of the output directory will
+      > indirectly depend on files that are filtered out by the
+      > function. This will trigger a rebuild even when a filtered out
+      > file is changed. Use `builtins.path` instead, which allows
+      > specifying the name of the output directory.
+
       This function allows you to copy sources into the Nix store while
       filtering certain files. For instance, suppose that you want to use
       the directory `source-dir` as an input to a Nix expression, e.g.
@@ -1874,18 +2001,13 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
     Value * filterFun = nullptr;
     auto method = FileIngestionMethod::Recursive;
     std::optional<Hash> expectedHash;
+    PathSet context;
 
     for (auto & attr : *args[0]->attrs) {
         const string & n(attr.name);
-        if (n == "path") {
-            PathSet context;
+        if (n == "path")
             path = state.coerceToPath(*attr.pos, *attr.value, context);
-            if (!context.empty())
-                throw EvalError({
-                    .msg = hintfmt("string '%1%' cannot refer to other paths", path),
-                    .errPos = *attr.pos
-                });
-        } else if (attr.name == state.sName)
+        else if (attr.name == state.sName)
             name = state.forceStringNoCtx(*attr.value, *attr.pos);
         else if (n == "filter") {
             state.forceValue(*attr.value, pos);
@@ -1908,7 +2030,7 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
     if (name.empty())
         name = baseNameOf(path);
 
-    addPath(state, pos, name, path, filterFun, method, expectedHash, v);
+    addPath(state, pos, name, path, filterFun, method, expectedHash, v, context);
 }
 
 static RegisterPrimOp primop_path({
@@ -1918,26 +2040,26 @@ static RegisterPrimOp primop_path({
       An enrichment of the built-in path type, based on the attributes
       present in *args*. All are optional except `path`:
 
-        - path  
+        - path\
           The underlying path.
 
-        - name  
+        - name\
           The name of the path when added to the store. This can used to
           reference paths that have nix-illegal characters in their names,
           like `@`.
 
-        - filter  
+        - filter\
           A function of the type expected by `builtins.filterSource`,
           with the same semantics.
 
-        - recursive  
+        - recursive\
           When `false`, when `path` is added to the store it is with a
           flat hash, rather than a hash of the NAR serialization of the
           file. Thus, `path` must refer to a regular file, not a
           directory. This allows similar behavior to `fetchurl`. Defaults
           to `true`.
 
-        - sha256  
+        - sha256\
           When provided, this is the expected hash of the file at the
           path. Evaluation will fail if the hash is incorrect, and
           providing a hash allows `builtins.path` to be used even when the
@@ -2014,14 +2136,15 @@ void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v)
     string attr = state.forceStringNoCtx(*args[0], pos);
     state.forceAttrs(*args[1], pos);
     // !!! Should we create a symbol here or just do a lookup?
-    Bindings::iterator i = args[1]->attrs->find(state.symbols.create(attr));
-    if (i == args[1]->attrs->end())
-        throw EvalError({
-            .msg = hintfmt("attribute '%1%' missing", attr),
-            .errPos = pos
-        });
+    Bindings::iterator i = getAttr(
+        state,
+        "getAttr",
+        attr,
+        args[1]->attrs,
+        pos
+    );
     // !!! add to stack trace?
-    if (state.countCalls && i->pos) state.attrSelects[*i->pos]++;
+    if (state.countCalls && *i->pos != noPos) state.attrSelects[*i->pos]++;
     state.forceValue(*i->value, pos);
     v = *i->value;
 }
@@ -2146,22 +2269,25 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
         Value & v2(*args[0]->listElems()[i]);
         state.forceAttrs(v2, pos);
 
-        Bindings::iterator j = v2.attrs->find(state.sName);
-        if (j == v2.attrs->end())
-            throw TypeError({
-                .msg = hintfmt("'name' attribute missing in a call to 'listToAttrs'"),
-                .errPos = pos
-            });
-        string name = state.forceStringNoCtx(*j->value, pos);
+        Bindings::iterator j = getAttr(
+            state,
+            "listToAttrs",
+            state.sName,
+            v2.attrs,
+            pos
+        );
+
+        string name = state.forceStringNoCtx(*j->value, *j->pos);
 
         Symbol sym = state.symbols.create(name);
         if (seen.insert(sym).second) {
-            Bindings::iterator j2 = v2.attrs->find(state.symbols.create(state.sValue));
-            if (j2 == v2.attrs->end())
-                throw TypeError({
-                    .msg = hintfmt("'value' attribute missing in a call to 'listToAttrs'"),
-                    .errPos = pos
-                });
+            Bindings::iterator j2 = getAttr(
+                state,
+                "listToAttrs",
+                state.sValue,
+                v2.attrs,
+                pos
+            );
             v.attrs->push_back(Attr(sym, j2->value, j2->pos));
         }
     }
@@ -2269,7 +2395,7 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
             .errPos = pos
         });
 
-    if (!args[0]->lambda.fun->matchAttrs) {
+    if (!args[0]->lambda.fun->hasFormals()) {
         state.mkAttrs(v, 0);
         return;
     }
@@ -2278,7 +2404,7 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
     for (auto & i : args[0]->lambda.fun->formals->formals) {
         // !!! should optimise booleans (allocate only once)
         Value * value = state.allocValue();
-        v.attrs->push_back(Attr(i.name, value, &i.pos));
+        v.attrs->push_back(Attr(i.name, value, ptr(&i.pos)));
         mkBool(*value, i.def);
     }
     v.attrs->sort();
@@ -2424,7 +2550,7 @@ static RegisterPrimOp primop_tail({
       the argument isn’t a list or is an empty list.
 
       > **Warning**
-      > 
+      >
       > This function should generally be avoided since it's inefficient:
       > unlike Haskell's `tail`, it takes O(n) time, so recursing over a
       > list by repeatedly calling `tail` takes O(n^2) time.
@@ -2802,7 +2928,12 @@ static void prim_concatMap(EvalState & state, const Pos & pos, Value * * args, V
     for (unsigned int n = 0; n < nrLists; ++n) {
         Value * vElem = args[1]->listElems()[n];
         state.callFunction(*args[0], *vElem, lists[n], pos);
-        state.forceList(lists[n], pos);
+        try {
+            state.forceList(lists[n], lists[n].determinePos(args[0]->determinePos(pos)));
+        } catch (TypeError &e) {
+            e.addTrace(pos, hintfmt("while invoking '%s'", "concatMap"));
+            throw;
+        }
         len += lists[n].listSize();
     }
 
@@ -3013,7 +3144,7 @@ static RegisterPrimOp primop_toString({
 
         - A path (e.g., `toString /foo/bar` yields `"/foo/bar"`.
 
-        - A set containing `{ __toString = self: ...; }`.
+        - A set containing `{ __toString = self: ...; }` or `{ outPath = ...; }`.
 
         - An integer.
 
@@ -3098,7 +3229,7 @@ static void prim_hashString(EvalState & state, const Pos & pos, Value * * args,
     PathSet context; // discarded
     string s = state.forceString(*args[1], context, pos);
 
-    mkString(v, hashString(*ht, s).to_string(Base16, false), context);
+    mkString(v, hashString(*ht, s).to_string(Base16, false));
 }
 
 static RegisterPrimOp primop_hashString({
@@ -3505,15 +3636,13 @@ static RegisterPrimOp primop_splitVersion({
 RegisterPrimOp::PrimOps * RegisterPrimOp::primOps;
 
 
-RegisterPrimOp::RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun,
-    std::optional<std::string> requiredFeature)
+RegisterPrimOp::RegisterPrimOp(std::string name, size_t arity, PrimOpFun fun)
 {
     if (!primOps) primOps = new PrimOps;
     primOps->push_back({
         .name = name,
         .args = {},
         .arity = arity,
-        .requiredFeature = std::move(requiredFeature),
         .fun = fun
     });
 }
@@ -3549,9 +3678,7 @@ void EvalState::createBaseEnv()
     if (!evalSettings.pureEval) {
         mkInt(v, time(0));
         addConstant("__currentTime", v);
-    }
 
-    if (!evalSettings.pureEval) {
         mkString(v, settings.thisSystem.get());
         addConstant("__currentSystem", v);
     }
@@ -3589,14 +3716,13 @@ void EvalState::createBaseEnv()
 
     if (RegisterPrimOp::primOps)
         for (auto & primOp : *RegisterPrimOp::primOps)
-            if (!primOp.requiredFeature || settings.isExperimentalFeatureEnabled(*primOp.requiredFeature))
-                addPrimOp({
-                    .fun = primOp.fun,
-                    .arity = std::max(primOp.args.size(), primOp.arity),
-                    .name = symbols.create(primOp.name),
-                    .args = std::move(primOp.args),
-                    .doc = primOp.doc,
-                });
+            addPrimOp({
+                .fun = primOp.fun,
+                .arity = std::max(primOp.args.size(), primOp.arity),
+                .name = symbols.create(primOp.name),
+                .args = std::move(primOp.args),
+                .doc = primOp.doc,
+            });
 
     /* Add a wrapper around the derivation primop that computes the
        `drvPath' and `outPath' attributes lazily. */