Add builtins.unique [WIP]

This cuts ~4.5s from "nix-env -qaP -f `<nixpkgs>` --out-path" and reduces memory allocations from 7.49 to 7.16 GiB. Note that builtins.unique requires a less-than comparator function, which is a change from the 'unique' function in Nixpkgs which uses an equality function.
Add environment variable NIX_SHOW_SYMBOLS for dumping the symbol table
2019-04-12 22:47:14 +02:00 · 2019-04-11 23:04:13 +02:00 · 2019-04-01 21:09:49 +02:00 · 2019-04-01 21:09:35 +02:00 · 2019-04-01 21:09:25 +02:00 · 2019-03-27 21:09:31 +01:00
66 changed files with 626 additions and 350 deletions
--- a/.gitignore
+++ b/.gitignore
@@ -81,6 +81,9 @@ perl/Makefile.config
 /tests/common.sh
 /tests/dummy
 /tests/result*
+/tests/restricted-innocent
+/tests/shell
+/tests/shell.drv

 # /tests/lang/
 /tests/lang/*.out
--- a/.version
+++ b/.version
@@ -0,0 +1 @@
+2.3
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -1,4 +1,6 @@
+AR = @AR@
 BDW_GC_LIBS = @BDW_GC_LIBS@
+BUILD_SHARED_LIBS = @BUILD_SHARED_LIBS@
 CC = @CC@
 CFLAGS = @CFLAGS@
 CXX = @CXX@
--- a/configure.ac
+++ b/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_SRCDIR(README.md)
 AC_CONFIG_AUX_DIR(config)

@@ -62,8 +62,9 @@ CXXFLAGS=
 AC_PROG_CC
 AC_PROG_CXX
 AC_PROG_CPP
-AX_CXX_COMPILE_STDCXX_14
+AX_CXX_COMPILE_STDCXX_17

+AC_CHECK_TOOL([AR], [ar])

 # Use 64-bit file system calls so that we can support files > 2 GiB.
 AC_SYS_LARGEFILE
@@ -267,6 +268,15 @@ AC_ARG_WITH(sandbox-shell, AC_HELP_STRING([--with-sandbox-shell=PATH],
  sandbox_shell=$withval)
 AC_SUBST(sandbox_shell)

+AC_ARG_ENABLE(shared, AC_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.])
+else
+  AC_SUBST(BUILD_SHARED_LIBS, 0, [Whether to build shared libraries.])
+fi
+

 # Expand all variables in config.status.
 test "$prefix" = NONE && prefix=$ac_default_prefix
--- a/doc/manual/advanced-topics/distributed-builds.xml
+++ b/doc/manual/advanced-topics/distributed-builds.xml
@@ -180,4 +180,8 @@ builders = @/etc/nix/machines
 causes the list of machines in <filename>/etc/nix/machines</filename>
 to be included. (This is the default.)</para>

+<para>If you want the builders to use caches, you likely want to set
+the option <link linkend='conf-builders-use-substitutes'><literal>builders-use-substitutes</literal></link>
+in your local <filename>nix.conf</filename>.</para>
+
 </chapter>
--- a/doc/manual/command-ref/conf-file.xml
+++ b/doc/manual/command-ref/conf-file.xml
@@ -657,7 +657,8 @@ password <replaceable>my-password</replaceable>
    <varname>__noChroot</varname> attribute set to
    <literal>true</literal> do not run in sandboxes.</para>

-    <para>The default is <literal>false</literal>.</para>
+    <para>The default is <literal>true</literal> on Linux and
+    <literal>false</literal> on all other platforms.</para>

    </listitem>

--- a/doc/manual/command-ref/env-common.xml
+++ b/doc/manual/command-ref/env-common.xml
@@ -52,10 +52,15 @@ nixpkgs=/home/eelco/Dev/nixpkgs-branch:/etc/nixos</screen>
    <envar>NIX_PATH</envar> to

    <screen>
-nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-14.12.tar.gz</screen>
+nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-15.09.tar.gz</screen>

    tells Nix to download the latest revision in the Nixpkgs/NixOS
-    14.12 channel.</para>
+    15.09 channel.</para>
+
+    <para>A following shorthand can be used to refer to the official channels:
+    
+    <screen>nixpkgs=channel:nixos-15.09</screen>
+    </para>

    <para>The search path can be extended using the <option
    linkend="opt-I">-I</option> option, which takes precedence over
--- a/doc/manual/command-ref/nix-shell.xml
+++ b/doc/manual/command-ref/nix-shell.xml
@@ -337,7 +337,7 @@ following Haskell script uses a specific branch of Nixpkgs/NixOS (the

 <programlisting><![CDATA[
 #! /usr/bin/env nix-shell
-#! nix-shell -i runghc -p haskellPackages.ghc haskellPackages.HTTP haskellPackages.tagsoup
+#! nix-shell -i runghc -p "haskellPackages.ghcWithPackages (ps: [ps.HTTP ps.tagsoup])"
 #! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs-channels/archive/nixos-18.03.tar.gz

 import Network.HTTP
--- a/doc/manual/command-ref/nix-store.xml
+++ b/doc/manual/command-ref/nix-store.xml
@@ -1282,6 +1282,7 @@ ktorrent-2.2.1/NEWS
  <cmdsynopsis>
    <command>nix-store</command>
    <arg choice='plain'><option>--dump-db</option></arg>
+    <arg rep='repeat'><replaceable>paths</replaceable></arg>
  </cmdsynopsis>
 </refsection>

@@ -1292,6 +1293,13 @@ Nix database to standard output.  It can be loaded into an empty Nix
 store using <option>--load-db</option>.  This is useful for making
 backups and when migrating to different database schemas.</para>

+<para>By default, <option>--dump-db</option> will dump the entire Nix
+database.  When one or more store paths is passed, only the subset of
+the Nix database for those store paths is dumped.  As with
+<option>--export</option>, the user is responsible for passing all the
+store paths for a closure.  See <option>--export</option> for an
+example.</para>
+
 </refsection>

 </refsection>
--- a/doc/manual/expressions/builtins.xml
+++ b/doc/manual/expressions/builtins.xml
@@ -23,6 +23,7 @@ available as <function>builtins.derivation</function>.</para>

  <varlistentry xml:id='builtin-abort'>
    <term><function>abort</function> <replaceable>s</replaceable></term>
+    <term><function>builtins.abort</function> <replaceable>s</replaceable></term>

    <listitem><para>Abort Nix expression evaluation, print error
    message <replaceable>s</replaceable>.</para></listitem>
@@ -251,6 +252,8 @@ if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>
  <varlistentry xml:id='builtin-derivation'>
    <term><function>derivation</function>
    <replaceable>attrs</replaceable></term>
+    <term><function>builtins.derivation</function>
+    <replaceable>attrs</replaceable></term>

    <listitem><para><function>derivation</function> is described in
    <xref linkend='ssec-derivation' />.</para></listitem>
@@ -260,6 +263,7 @@ if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>

  <varlistentry xml:id='builtin-dirOf'>
    <term><function>dirOf</function> <replaceable>s</replaceable></term>
+    <term><function>builtins.dirOf</function> <replaceable>s</replaceable></term>

    <listitem><para>Return the directory part of the string
    <replaceable>s</replaceable>, that is, everything before the final
@@ -318,6 +322,8 @@ if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>
  <varlistentry xml:id='builtin-fetchTarball'>
    <term><function>fetchTarball</function>
    <replaceable>url</replaceable></term>
+    <term><function>builtins.fetchTarball</function>
+    <replaceable>url</replaceable></term>

    <listitem><para>Download the specified URL, unpack it and return
    the path of the unpacked tree. The file must be a tape archive
@@ -693,8 +699,8 @@ builtins.genList (x: x * x) 5
    <listitem><para>Return a base-16 representation of the
    cryptographic hash of string <replaceable>s</replaceable>.  The
    hash algorithm specified by <replaceable>type</replaceable> must
-    be one of <literal>"md5"</literal>, <literal>"sha1"</literal> or
-    <literal>"sha256"</literal>.</para></listitem>
+    be one of <literal>"md5"</literal>, <literal>"sha1"</literal>,
+    <literal>"sha256"</literal> or <literal>"sha512"</literal>.</para></listitem>

  </varlistentry>

@@ -714,6 +720,8 @@ builtins.genList (x: x * x) 5
  <varlistentry xml:id='builtin-import'>
    <term><function>import</function>
    <replaceable>path</replaceable></term>
+    <term><function>builtins.import</function>
+    <replaceable>path</replaceable></term>

    <listitem><para>Load, parse and return the Nix expression in the
    file <replaceable>path</replaceable>.  If <replaceable>path
@@ -853,10 +861,20 @@ x: x + 456</programlisting>

  </varlistentry>

+  <varlistentry><term><function>builtins.isPath</function>
+  <replaceable>e</replaceable></term>
+
+    <listitem><para>Return <literal>true</literal> if
+    <replaceable>e</replaceable> evaluates to a path, and
+    <literal>false</literal> otherwise.</para></listitem>
+
+  </varlistentry>

  <varlistentry xml:id='builtin-isNull'>
    <term><function>isNull</function>
    <replaceable>e</replaceable></term>
+    <term><function>builtins.isNull</function>
+    <replaceable>e</replaceable></term>

    <listitem><para>Return <literal>true</literal> if
    <replaceable>e</replaceable> evaluates to <literal>null</literal>,
@@ -925,6 +943,8 @@ builtins.listToAttrs
  <varlistentry xml:id='builtin-map'>
    <term><function>map</function>
    <replaceable>f</replaceable> <replaceable>list</replaceable></term>
+    <term><function>builtins.map</function>
+    <replaceable>f</replaceable> <replaceable>list</replaceable></term>

    <listitem><para>Apply the function <replaceable>f</replaceable> to
    each element in the list <replaceable>list</replaceable>.  For
@@ -1119,6 +1139,8 @@ Evaluates to <literal>[ "foo" ]</literal>.
  <varlistentry xml:id='builtin-removeAttrs'>
    <term><function>removeAttrs</function>
    <replaceable>set</replaceable> <replaceable>list</replaceable></term>
+    <term><function>builtins.removeAttrs</function>
+    <replaceable>set</replaceable> <replaceable>list</replaceable></term>

    <listitem><para>Remove the attributes listed in
    <replaceable>list</replaceable> from
@@ -1287,6 +1309,8 @@ builtins.substring 0 3 "nixos"
  <varlistentry xml:id='builtin-throw'>
    <term><function>throw</function>
    <replaceable>s</replaceable></term>
+    <term><function>builtins.throw</function>
+    <replaceable>s</replaceable></term>

    <listitem><para>Throw an error message
    <replaceable>s</replaceable>.  This usually aborts Nix expression
@@ -1405,6 +1429,7 @@ in foo</programlisting>

  <varlistentry xml:id='builtin-toString'>
    <term><function>toString</function> <replaceable>e</replaceable></term>
+    <term><function>builtins.toString</function> <replaceable>e</replaceable></term>

    <listitem><para>Convert the expression
    <replaceable>e</replaceable> to a string.
--- a/doc/manual/packages/s3-substituter.xml
+++ b/doc/manual/packages/s3-substituter.xml
@@ -89,7 +89,7 @@ the S3 URL:</para>
    "Version": "2012-10-17",
    "Statement": [
        {
-            "Sid": "AlowDirectReads",
+            "Sid": "AllowDirectReads",
            "Action": [
                "s3:GetObject",
                "s3:GetBucketLocation"
--- a/misc/launchd/org.nixos.nix-daemon.plist.in
+++ b/misc/launchd/org.nixos.nix-daemon.plist.in
@@ -2,6 +2,11 @@
 <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
 <plist version="1.0">
  <dict>
+    <key>EnvironmentVariables</key>
+    <dict>
+      <key>OBJC_DISABLE_INITIALIZE_FORK_SAFETY</key>
+      <string>YES</string>
+    </dict>
    <key>Label</key>
    <string>org.nixos.nix-daemon</string>
    <key>KeepAlive</key>
--- a/mk/libraries.mk
+++ b/mk/libraries.mk
@@ -125,7 +125,7 @@ define build-library
    $(1)_PATH := $$(_d)/$$($(1)_NAME).a

    $$($(1)_PATH): $$($(1)_OBJS) | $$(_d)/
-	$(trace-ar) ar crs $$@ $$?
+	$(trace-ar) $(AR) crs $$@ $$?

    $(1)_LDFLAGS_USE += $$($(1)_PATH) $$($(1)_LDFLAGS)

--- a/perl/configure.ac
+++ b/perl/configure.ac
@@ -1,4 +1,4 @@
-AC_INIT(nix-perl, m4_esyscmd([bash -c "echo -n $(cat ../version)$VERSION_SUFFIX"]))
+AC_INIT(nix-perl, m4_esyscmd([bash -c "echo -n $(cat ../.version)$VERSION_SUFFIX"]))
 AC_CONFIG_SRCDIR(MANIFEST)
 AC_CONFIG_AUX_DIR(../config)

--- a/release.nix
+++ b/release.nix
@@ -1,5 +1,5 @@
 { nix ? builtins.fetchGit ./.
-, nixpkgs ? builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-18.09"; }
+, nixpkgs ? builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-19.03"; }
 , officialRelease ? false
 , systems ? [ "x86_64-linux" "i686-linux" "x86_64-darwin" "aarch64-linux" ]
 }:
@@ -18,7 +18,7 @@ let

      releaseTools.sourceTarball {
        name = "nix-tarball";
-        version = builtins.readFile ./version;
+        version = builtins.readFile ./.version;
        versionSuffix = if officialRelease then "" else "pre${toString nix.revCount}_${nix.shortRev}";
        src = nix;
        inherit officialRelease;
@@ -278,7 +278,6 @@ let
      pkgs.runCommand "eval-nixos" { buildInputs = [ build.x86_64-linux ]; }
        ''
          export NIX_STATE_DIR=$TMPDIR
-          nix-store --init

          nix-instantiate ${nixpkgs}/nixos/release-combined.nix -A tested --dry-run \
            --arg nixpkgs '{ outPath = ${nixpkgs}; revCount = 123; shortRev = "abcdefgh"; }'
@@ -296,7 +295,7 @@ let

          substitute ${./scripts/install.in} $out/install \
            ${pkgs.lib.concatMapStrings
-              (system: "--replace '@binaryTarball_${system}@' $(nix hash-file --type sha256 ${binaryTarball.${system}}/*.tar.bz2) ")
+              (system: "--replace '@binaryTarball_${system}@' $(nix hash-file --base16 --type sha256 ${binaryTarball.${system}}/*.tar.bz2) ")
              [ "x86_64-linux" "i686-linux" "x86_64-darwin" "aarch64-linux" ]
            } \
            --replace '@nixVersion@' ${build.x86_64-linux.src.version}
--- a/scripts/install-multi-user.sh
+++ b/scripts/install-multi-user.sh
@@ -674,9 +674,6 @@ $NIX_INSTALLED_NIX.
 EOF
        fi

-        _sudo "to initialize the Nix Database" \
-              $NIX_INSTALLED_NIX/bin/nix-store --init
-
        cat ./.reginfo \
            | _sudo "to load data for the first time in to the Nix Database" \
                   "$NIX_INSTALLED_NIX/bin/nix-store" --load-db
@@ -747,7 +744,6 @@ build-users-group = $NIX_BUILD_GROUP_NAME

 max-jobs = $NIX_USER_COUNT
 cores = 1
-sandbox = false
 EOF
    _sudo "to place the default nix daemon configuration (part 2)" \
          install -m 0664 "$SCRATCH/nix.conf" /etc/nix/nix.conf
--- a/scripts/install-nix-from-closure.sh
+++ b/scripts/install-nix-from-closure.sh
@@ -109,12 +109,6 @@ for i in $(cd "$self/store" >/dev/null && echo ./*); do
 done
 echo "" >&2

-echo "initialising Nix database..." >&2
-if ! $nix/bin/nix-store --init; then
-    echo "$0: failed to initialize the Nix database" >&2
-    exit 1
-fi
-
 if ! "$nix/bin/nix-store" --load-db < "$self/.reginfo"; then
    echo "$0: unable to register valid paths" >&2
    exit 1
--- a/scripts/nix-profile.sh.in
+++ b/scripts/nix-profile.sh.in
@@ -75,7 +75,7 @@ if [ -n "$HOME" ] && [ -n "$USER" ]; then
        export NIX_SSL_CERT_FILE="$NIX_LINK/etc/ca-bundle.crt"
    fi

-    if [ -n "${MANPATH}" ]; then
+    if [ -n "${MANPATH-}" ]; then
        export MANPATH="$NIX_LINK/share/man:$MANPATH"
    fi

--- a/shell.nix
+++ b/shell.nix
@@ -1,6 +1,6 @@
 { useClang ? false }:

-with import (builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-18.09"; }) {};
+with import (builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-19.03"; }) {};

 with import ./release-common.nix { inherit pkgs; };

--- a/src/build-remote/build-remote.cc
+++ b/src/build-remote/build-remote.cc
@@ -38,6 +38,12 @@ static AutoCloseFD openSlotLock(const Machine & m, unsigned long long slot)
    return openLockFile(fmt("%s/%s-%d", currentLoad, escapeUri(m.storeUri), slot), true);
 }

+static bool allSupportedLocally(const std::set<std::string>& requiredFeatures) {
+    for (auto & feature : requiredFeatures)
+        if (!settings.systemFeatures.get().count(feature)) return false;
+    return true;
+}
+
 static int _main(int argc, char * * argv)
 {
    {
@@ -97,9 +103,10 @@ static int _main(int argc, char * * argv)
            source >> drvPath;
            auto requiredFeatures = readStrings<std::set<std::string>>(source);

-            auto canBuildLocally = amWilling
-                &&  (  neededSystem == settings.thisSystem
-                    || settings.extraPlatforms.get().count(neededSystem) > 0);
+             auto canBuildLocally = amWilling
+                 &&  (  neededSystem == settings.thisSystem
+                     || settings.extraPlatforms.get().count(neededSystem) > 0)
+                 &&  allSupportedLocally(requiredFeatures);

            /* Error ignored here, will be caught later */
            mkdir(currentLoad.c_str(), 0777);
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -130,6 +130,16 @@ std::ostream & operator << (std::ostream & str, const Value & v)
 }


+const Value *getPrimOp(const Value &v) {
+    const Value * primOp = &v;
+    while (primOp->type == tPrimOpApp) {
+        primOp = primOp->primOpApp.left;
+    }
+    assert(primOp->type == tPrimOp);
+    return primOp;
+}
+
+
 string showType(const Value & v)
 {
    switch (v.type) {
@@ -144,8 +154,10 @@ string showType(const Value & v)
        case tApp: return "a function application";
        case tLambda: return "a function";
        case tBlackhole: return "a black hole";
-        case tPrimOp: return "a built-in function";
-        case tPrimOpApp: return "a partially applied built-in function";
+        case tPrimOp:
+            return fmt("the built-in function '%s'", string(v.primOp->name));
+        case tPrimOpApp:
+            return fmt("the partially applied built-in function '%s'", string(getPrimOp(v)->primOp->name));
        case tExternal: return v.external->showType();
        case tFloat: return "a float";
    }
@@ -1799,6 +1811,7 @@ void EvalState::printStats()
            gc.attr("totalBytes", totalBytes);
        }
 #endif
+
        if (countCalls) {
            {
                auto obj = topObj.object("primops");
@@ -1834,6 +1847,11 @@ void EvalState::printStats()
                }
            }
        }
+
+        if (getEnv("NIX_SHOW_SYMBOLS", "0") != "0") {
+            auto list = topObj.list("symbols");
+            symbols.dump([&](const std::string & s) { list.elem(s); });
+        }
    }
 }

--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -81,7 +81,7 @@ public:

    /* The allowed filesystem paths in restricted or pure evaluation
       mode. */
-    std::experimental::optional<PathSet> allowedPaths;
+    std::optional<PathSet> allowedPaths;

    Value vEmptySet;

@@ -316,6 +316,9 @@ private:
 /* Return a string representing the type of the value `v'. */
 string showType(const Value & v);

+/* Decode a context string ‘!<name>!<path>’ into a pair <path,
+   name>. */
+std::pair<string, string> decodeContext(const string & s);

 /* If `path' refers to a directory, then append "/default.nix". */
 Path resolveExprPath(Path path);
--- a/src/libexpr/get-drvs.cc
+++ b/src/libexpr/get-drvs.cc
@@ -295,7 +295,7 @@ static bool getDerivation(EvalState & state, Value & v,
 }


-std::experimental::optional<DrvInfo> getDerivation(EvalState & state, Value & v,
+std::optional<DrvInfo> getDerivation(EvalState & state, Value & v,
    bool ignoreAssertionFailures)
 {
    Done done;
--- a/src/libexpr/get-drvs.hh
+++ b/src/libexpr/get-drvs.hh
@@ -78,7 +78,7 @@ typedef list<DrvInfo> DrvInfos;

 /* If value `v' denotes a derivation, return a DrvInfo object
   describing it. Otherwise return nothing. */
-std::experimental::optional<DrvInfo> getDerivation(EvalState & state,
+std::optional<DrvInfo> getDerivation(EvalState & state,
    Value & v, bool ignoreAssertionFailures);

 void getDerivations(EvalState & state, Value & v, const string & pathPrefix,
--- a/src/libexpr/nix-expr.pc.in
+++ b/src/libexpr/nix-expr.pc.in
@@ -7,4 +7,4 @@ Description: Nix Package Manager
 Version: @PACKAGE_VERSION@
 Requires: nix-store bdw-gc
 Libs: -L${libdir} -lnixexpr
-Cflags: -I${includedir}/nix -std=c++14
+Cflags: -I${includedir}/nix -std=c++17
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -1,7 +1,7 @@
 %glr-parser
 %pure-parser
 %locations
-%error-verbose
+%define parse.error verbose
 %defines
 /* %no-lines */
 %parse-param { void * scanner }
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -315,6 +315,12 @@ static void prim_isBool(EvalState & state, const Pos & pos, Value * * args, Valu
    mkBool(v, args[0]->type == tBool);
 }

+/* Determine whether the argument is a path. */
+static void prim_isPath(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    state.forceValue(*args[0]);
+    mkBool(v, args[0]->type == tPath);
+}

 struct CompareValues
 {
@@ -335,6 +341,8 @@ struct CompareValues
                return strcmp(v1->string.s, v2->string.s) < 0;
            case tPath:
                return strcmp(v1->path, v2->path) < 0;
+            case tAttrs:
+                return v1 < v2; // FIXME
            default:
                throw EvalError(format("cannot compare %1% with %2%") % showType(*v1) % showType(*v2));
        }
@@ -555,7 +563,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *

    PathSet context;

-    std::experimental::optional<std::string> outputHash;
+    std::optional<std::string> outputHash;
    std::string outputHashAlgo;
    bool outputHashRecursive = false;

@@ -687,21 +695,12 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
            }
        }

-        /* See prim_unsafeDiscardOutputDependency. */
-        else if (path.at(0) == '~')
-            drv.inputSrcs.insert(string(path, 1));
-
        /* Handle derivation outputs of the form ‘!<name>!<path>’. */
        else if (path.at(0) == '!') {
            std::pair<string, string> ctx = decodeContext(path);
            drv.inputDrvs[ctx.first].insert(ctx.second);
        }

-        /* Handle derivation contexts returned by
-           ‘builtins.storePath’. */
-        else if (isDerivation(path))
-            drv.inputDrvs[path] = state.store->queryDerivationOutputNames(path);
-
        /* Otherwise it's a source file. */
        else
            drv.inputSrcs.insert(path);
@@ -1004,13 +1003,8 @@ static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Valu
    PathSet refs;

    for (auto path : context) {
-        if (path.at(0) == '=') path = string(path, 1);
-        if (isDerivation(path)) {
-            /* See prim_unsafeDiscardOutputDependency. */
-            if (path.at(0) != '~')
-                throw EvalError(format("in 'toFile': the file '%1%' cannot refer to derivation outputs, at %2%") % name % pos);
-            path = string(path, 1);
-        }
+        if (path.at(0) != '/')
+            throw EvalError(format("in 'toFile': the file '%1%' cannot refer to derivation outputs, at %2%") % name % pos);
        refs.insert(path);
    }

@@ -1584,7 +1578,6 @@ static void prim_sort(EvalState & state, const Pos & pos, Value * * args, Value
        v.listElems()[n] = args[1]->listElems()[n];
    }

-
    auto comparator = [&](Value * a, Value * b) {
        /* Optimization: if the comparator is lessThan, bypass
           callFunction. */
@@ -1604,6 +1597,62 @@ static void prim_sort(EvalState & state, const Pos & pos, Value * * args, Value
 }


+static void prim_unique(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    state.forceFunction(*args[0], pos);
+    state.forceList(*args[1], pos);
+
+    auto len = args[1]->listSize();
+
+    Value * vs[len];
+    for (size_t n = 0; n < len; ++n) {
+        auto v2 = args[1]->listElems()[n];
+        state.forceValue(*v2);
+        vs[n] = v2;
+    }
+
+    auto comparator = [&](Value * a, Value * b) {
+        /* Optimization: if the comparator is lessThan, bypass
+           callFunction. */
+        if (args[0]->type == tPrimOp && args[0]->primOp->fun == prim_lessThan)
+            return CompareValues()(a, b);
+
+        Value vTmp1, vTmp2;
+        state.callFunction(*args[0], *a, vTmp1, pos);
+        state.callFunction(vTmp1, *b, vTmp2, pos);
+        return state.forceBool(vTmp2, pos);
+    };
+
+    std::sort(vs, vs + len, comparator);
+
+    auto outLen = std::min((size_t) 1, len);
+    for (size_t n = 1; n < len; n++) {
+        if (comparator(vs[outLen - 1], vs[n])) {
+            vs[outLen++] = vs[n];
+        }
+    }
+
+    std::sort(vs, vs + outLen);
+
+    state.mkList(v, outLen);
+
+    size_t outPos = 0;
+    for (size_t n = 0; n < len; n++) {
+        auto v2 = args[1]->listElems()[n];
+        auto i = std::lower_bound(vs, vs + outLen, v2);
+        if (*i == v2) {
+            // Remove v2 from the set by setting its least significant
+            // bit. (This doesn't change the sort order.)
+            *i = (Value *) (((ptrdiff_t) v2) | 1);
+            assert(outPos < outLen);
+            v.listElems()[outPos++] = v2;
+        }
+    }
+
+    assert(outPos == outLen);
+}
+
+
 static void prim_partition(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
    state.forceFunction(*args[0], pos);
@@ -1794,41 +1843,6 @@ static void prim_stringLength(EvalState & state, const Pos & pos, Value * * args
 }


-static void prim_unsafeDiscardStringContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
-{
-    PathSet context;
-    string s = state.coerceToString(pos, *args[0], context);
-    mkString(v, s, PathSet());
-}
-
-
-static void prim_hasContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
-{
-    PathSet context;
-    state.forceString(*args[0], context, pos);
-    mkBool(v, !context.empty());
-}
-
-
-/* Sometimes we want to pass a derivation path (i.e. pkg.drvPath) to a
-   builder without causing the derivation to be built (for instance,
-   in the derivation that builds NARs in nix-push, when doing
-   source-only deployment).  This primop marks the string context so
-   that builtins.derivation adds the path to drv.inputSrcs rather than
-   drv.inputDrvs. */
-static void prim_unsafeDiscardOutputDependency(EvalState & state, const Pos & pos, Value * * args, Value & v)
-{
-    PathSet context;
-    string s = state.coerceToString(pos, *args[0], context);
-
-    PathSet context2;
-    for (auto & p : context)
-        context2.insert(p.at(0) == '=' ? "~" + string(p, 1) : p);
-
-    mkString(v, s, context2);
-}
-
-
 /* Return the cryptographic hash of a string in base-16. */
 static void prim_hashString(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
@@ -2218,6 +2232,7 @@ void EvalState::createBaseEnv()
    addPrimOp("__isInt", 1, prim_isInt);
    addPrimOp("__isFloat", 1, prim_isFloat);
    addPrimOp("__isBool", 1, prim_isBool);
+    addPrimOp("__isPath", 1, prim_isPath);
    addPrimOp("__genericClosure", 1, prim_genericClosure);
    addPrimOp("abort", 1, prim_abort);
    addPrimOp("__addErrorContext", 2, prim_addErrorContext);
@@ -2282,6 +2297,7 @@ void EvalState::createBaseEnv()
    addPrimOp("__all", 2, prim_all);
    addPrimOp("__genList", 2, prim_genList);
    addPrimOp("__sort", 2, prim_sort);
+    addPrimOp("__unique", 2, prim_unique);
    addPrimOp("__partition", 2, prim_partition);
    addPrimOp("__concatMap", 2, prim_concatMap);

@@ -2299,9 +2315,6 @@ void EvalState::createBaseEnv()
    addPrimOp("toString", 1, prim_toString);
    addPrimOp("__substring", 3, prim_substring);
    addPrimOp("__stringLength", 1, prim_stringLength);
-    addPrimOp("__hasContext", 1, prim_hasContext);
-    addPrimOp("__unsafeDiscardStringContext", 1, prim_unsafeDiscardStringContext);
-    addPrimOp("__unsafeDiscardOutputDependency", 1, prim_unsafeDiscardOutputDependency);
    addPrimOp("__hashString", 2, prim_hashString);
    addPrimOp("__match", 2, prim_match);
    addPrimOp("__split", 2, prim_split);
--- a/src/libexpr/primops/context.cc
+++ b/src/libexpr/primops/context.cc
@@ -0,0 +1,187 @@
+#include "primops.hh"
+#include "eval-inline.hh"
+#include "derivations.hh"
+
+namespace nix {
+
+static void prim_unsafeDiscardStringContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    PathSet context;
+    string s = state.coerceToString(pos, *args[0], context);
+    mkString(v, s, PathSet());
+}
+
+static RegisterPrimOp r1("__unsafeDiscardStringContext", 1, prim_unsafeDiscardStringContext);
+
+
+static void prim_hasContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    PathSet context;
+    state.forceString(*args[0], context, pos);
+    mkBool(v, !context.empty());
+}
+
+static RegisterPrimOp r2("__hasContext", 1, prim_hasContext);
+
+
+/* Sometimes we want to pass a derivation path (i.e. pkg.drvPath) to a
+   builder without causing the derivation to be built (for instance,
+   in the derivation that builds NARs in nix-push, when doing
+   source-only deployment).  This primop marks the string context so
+   that builtins.derivation adds the path to drv.inputSrcs rather than
+   drv.inputDrvs. */
+static void prim_unsafeDiscardOutputDependency(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    PathSet context;
+    string s = state.coerceToString(pos, *args[0], context);
+
+    PathSet context2;
+    for (auto & p : context)
+        context2.insert(p.at(0) == '=' ? string(p, 1) : p);
+
+    mkString(v, s, context2);
+}
+
+static RegisterPrimOp r3("__unsafeDiscardOutputDependency", 1, prim_unsafeDiscardOutputDependency);
+
+
+/* Extract the context of a string as a structured Nix value.
+
+   The context is represented as an attribute set whose keys are the
+   paths in the context set and whose values are attribute sets with
+   the following keys:
+     path: True if the relevant path is in the context as a plain store
+           path (i.e. the kind of context you get when interpolating
+           a Nix path (e.g. ./.) into a string). False if missing.
+     allOutputs: True if the relevant path is a derivation and it is
+                  in the context as a drv file with all of its outputs
+                  (i.e. the kind of context you get when referencing
+                  .drvPath of some derivation). False if missing.
+     outputs: If a non-empty list, the relevant path is a derivation
+              and the provided outputs are referenced in the context
+              (i.e. the kind of context you get when referencing
+              .outPath of some derivation). Empty list if missing.
+   Note that for a given path any combination of the above attributes
+   may be present.
+*/
+static void prim_getContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    struct ContextInfo {
+        bool path = false;
+        bool allOutputs = false;
+        Strings outputs;
+    };
+    PathSet context;
+    state.forceString(*args[0], context, pos);
+    auto contextInfos = std::map<Path, ContextInfo>();
+    for (const auto & p : context) {
+        Path drv;
+        string output;
+        const Path * path = &p;
+        if (p.at(0) == '=') {
+            drv = string(p, 1);
+            path = &drv;
+        } else if (p.at(0) == '!') {
+            std::pair<string, string> ctx = decodeContext(p);
+            drv = ctx.first;
+            output = ctx.second;
+            path = &drv;
+        }
+        auto isPath = drv.empty();
+        auto isAllOutputs = (!drv.empty()) && output.empty();
+
+        auto iter = contextInfos.find(*path);
+        if (iter == contextInfos.end()) {
+            contextInfos.emplace(*path, ContextInfo{isPath, isAllOutputs, output.empty() ? Strings{} : Strings{std::move(output)}});
+        } else {
+            if (isPath)
+                iter->second.path = true;
+            else if (isAllOutputs)
+                iter->second.allOutputs = true;
+            else
+                iter->second.outputs.emplace_back(std::move(output));
+        }
+    }
+
+    state.mkAttrs(v, contextInfos.size());
+
+    auto sPath = state.symbols.create("path");
+    auto sAllOutputs = state.symbols.create("allOutputs");
+    for (const auto & info : contextInfos) {
+        auto & infoVal = *state.allocAttr(v, state.symbols.create(info.first));
+        state.mkAttrs(infoVal, 3);
+        if (info.second.path)
+            mkBool(*state.allocAttr(infoVal, sPath), true);
+        if (info.second.allOutputs)
+            mkBool(*state.allocAttr(infoVal, sAllOutputs), true);
+        if (!info.second.outputs.empty()) {
+            auto & outputsVal = *state.allocAttr(infoVal, state.sOutputs);
+            state.mkList(outputsVal, info.second.outputs.size());
+            size_t i = 0;
+            for (const auto & output : info.second.outputs) {
+                mkString(*(outputsVal.listElems()[i++] = state.allocValue()), output);
+            }
+        }
+        infoVal.attrs->sort();
+    }
+    v.attrs->sort();
+}
+
+static RegisterPrimOp r4("__getContext", 1, prim_getContext);
+
+
+/* Append the given context to a given string.
+
+   See the commentary above unsafeGetContext for details of the
+   context representation.
+*/
+static void prim_appendContext(EvalState & state, const Pos & pos, Value * * args, Value & v)
+{
+    PathSet context;
+    auto orig = state.forceString(*args[0], context, pos);
+
+    state.forceAttrs(*args[1], pos);
+
+    auto sPath = state.symbols.create("path");
+    auto sAllOutputs = state.symbols.create("allOutputs");
+    for (auto & i : *args[1]->attrs) {
+        if (!state.store->isStorePath(i.name))
+            throw EvalError("Context key '%s' is not a store path, at %s", i.name, i.pos);
+        if (!settings.readOnlyMode)
+            state.store->ensurePath(i.name);
+        state.forceAttrs(*i.value, *i.pos);
+        auto iter = i.value->attrs->find(sPath);
+        if (iter != i.value->attrs->end()) {
+            if (state.forceBool(*iter->value, *iter->pos))
+                context.insert(i.name);
+        }
+
+        iter = i.value->attrs->find(sAllOutputs);
+        if (iter != i.value->attrs->end()) {
+            if (state.forceBool(*iter->value, *iter->pos)) {
+                if (!isDerivation(i.name)) {
+                    throw EvalError("Tried to add all-outputs context of %s, which is not a derivation, to a string, at %s", i.name, i.pos);
+                }
+                context.insert("=" + string(i.name));
+            }
+        }
+
+        iter = i.value->attrs->find(state.sOutputs);
+        if (iter != i.value->attrs->end()) {
+            state.forceList(*iter->value, *iter->pos);
+            if (iter->value->listSize() && !isDerivation(i.name)) {
+                throw EvalError("Tried to add derivation output context of %s, which is not a derivation, to a string, at %s", i.name, i.pos);
+            }
+            for (unsigned int n = 0; n < iter->value->listSize(); ++n) {
+                auto name = state.forceStringNoCtx(*iter->value->listElems()[n], *iter->pos);
+                context.insert("!" + name + "!" + string(i.name));
+            }
+        }
+    }
+
+    mkString(v, orig, context);
+}
+
+static RegisterPrimOp r5("__appendContext", 2, prim_appendContext);
+
+}
--- a/src/libexpr/primops/fetchGit.cc
+++ b/src/libexpr/primops/fetchGit.cc
@@ -26,7 +26,7 @@ struct GitInfo
 std::regex revRegex("^[0-9a-fA-F]{40}$");

 GitInfo exportGit(ref<Store> store, const std::string & uri,
-    std::experimental::optional<std::string> ref, std::string rev,
+    std::optional<std::string> ref, std::string rev,
    const std::string & name)
 {
    if (evalSettings.pureEval && rev == "")
@@ -190,7 +190,7 @@ GitInfo exportGit(ref<Store> store, const std::string & uri,
 static void prim_fetchGit(EvalState & state, const Pos & pos, Value * * args, Value & v)
 {
    std::string url;
-    std::experimental::optional<std::string> ref;
+    std::optional<std::string> ref;
    std::string rev;
    std::string name = "source";
    PathSet context;
--- a/src/libexpr/symbol-table.hh
+++ b/src/libexpr/symbol-table.hh
@@ -75,6 +75,13 @@ public:
    }

    size_t totalSize() const;
+
+    template<typename T>
+    void dump(T callback)
+    {
+        for (auto & s : symbols)
+            callback(s);
+    }
 };

 }
--- a/src/libmain/nix-main.pc.in
+++ b/src/libmain/nix-main.pc.in
@@ -6,4 +6,4 @@ Name: Nix
 Description: Nix Package Manager
 Version: @PACKAGE_VERSION@
 Libs: -L${libdir} -lnixmain
-Cflags: -I${includedir}/nix -std=c++14
+Cflags: -I${includedir}/nix -std=c++17
--- a/src/libstore/binary-cache-store.hh
+++ b/src/libstore/binary-cache-store.hh
@@ -72,24 +72,11 @@ public:

    bool isValidPathUncached(const Path & path) override;

-    PathSet queryAllValidPaths() override
-    { unsupported(); }
-
    void queryPathInfoUncached(const Path & path,
        Callback<std::shared_ptr<ValidPathInfo>> callback) override;

-    void queryReferrers(const Path & path,
-        PathSet & referrers) override
-    { unsupported(); }
-
-    PathSet queryDerivationOutputs(const Path & path) override
-    { unsupported(); }
-
-    StringSet queryDerivationOutputNames(const Path & path) override
-    { unsupported(); }
-
    Path queryPathFromHashPart(const string & hashPart) override
-    { unsupported(); }
+    { unsupported("queryPathFromHashPart"); }

    bool wantMassQuery() override { return wantMassQuery_; }

@@ -108,22 +95,10 @@ public:

    BuildResult buildDerivation(const Path & drvPath, const BasicDerivation & drv,
        BuildMode buildMode) override
-    { unsupported(); }
+    { unsupported("buildDerivation"); }

    void ensurePath(const Path & path) override
-    { unsupported(); }
-
-    void addTempRoot(const Path & path) override
-    { unsupported(); }
-
-    void addIndirectRoot(const Path & path) override
-    { unsupported(); }
-
-    Roots findRoots() override
-    { unsupported(); }
-
-    void collectGarbage(const GCOptions & options, GCResults & results) override
-    { unsupported(); }
+    { unsupported("ensurePath"); }

    ref<FSAccessor> getFSAccessor() override;

--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -12,6 +12,7 @@
 #include "json.hh"
 #include "nar-info.hh"
 #include "parsed-derivations.hh"
+#include "machines.hh"

 #include <algorithm>
 #include <iostream>
@@ -2193,7 +2194,6 @@ void DerivationGoal::startBuilder()
        userNamespaceSync.create();

        options.allowVfork = false;
-        options.restoreMountNamespace = false;

        Pid helper = startProcess([&]() {

@@ -2260,7 +2260,6 @@ void DerivationGoal::startBuilder()
 #endif
    {
        options.allowVfork = !buildUser && !drv->isBuiltin();
-        options.restoreMountNamespace = false;
        pid = startProcess([&]() {
            runChild();
        }, options);
@@ -2415,7 +2414,7 @@ void DerivationGoal::writeStructuredAttrs()
       objects consisting entirely of those values. (So nested
       arrays or objects are not supported.) */

-    auto handleSimpleType = [](const nlohmann::json & value) -> std::experimental::optional<std::string> {
+    auto handleSimpleType = [](const nlohmann::json & value) -> std::optional<std::string> {
        if (value.is_string())
            return shellEscape(value);

@@ -3313,8 +3312,8 @@ void DerivationGoal::checkOutputs(const std::map<Path, ValidPathInfo> & outputs)
        struct Checks
        {
            bool ignoreSelfRefs = false;
-            std::experimental::optional<uint64_t> maxSize, maxClosureSize;
-            std::experimental::optional<Strings> allowedReferences, allowedRequisites, disallowedReferences, disallowedRequisites;
+            std::optional<uint64_t> maxSize, maxClosureSize;
+            std::optional<Strings> allowedReferences, allowedRequisites, disallowedReferences, disallowedRequisites;
        };

        /* Compute the closure and closure size of some output. This
@@ -3361,7 +3360,7 @@ void DerivationGoal::checkOutputs(const std::map<Path, ValidPathInfo> & outputs)
                        info.path, closureSize, *checks.maxClosureSize);
            }

-            auto checkRefs = [&](const std::experimental::optional<Strings> & value, bool allowed, bool recursive)
+            auto checkRefs = [&](const std::optional<Strings> & value, bool allowed, bool recursive)
            {
                if (!value) return;

@@ -3415,7 +3414,7 @@ void DerivationGoal::checkOutputs(const std::map<Path, ValidPathInfo> & outputs)
                    if (maxClosureSize != output->end())
                        checks.maxClosureSize = maxClosureSize->get<uint64_t>();

-                    auto get = [&](const std::string & name) -> std::experimental::optional<Strings> {
+                    auto get = [&](const std::string & name) -> std::optional<Strings> {
                        auto i = output->find(name);
                        if (i != output->end()) {
                            Strings res;
@@ -4413,6 +4412,11 @@ static void primeCache(Store & store, const PathSet & paths)
    PathSet willBuild, willSubstitute, unknown;
    unsigned long long downloadSize, narSize;
    store.queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize, narSize);
+
+    if (!willBuild.empty() && 0 == settings.maxBuildJobs && getMachines().empty())
+        throw Error(
+            "%d derivations need to be built, but neither local builds ('--max-jobs') "
+            "nor remote builds ('--builders') are enabled", willBuild.size());
 }


--- a/src/libstore/download.cc
+++ b/src/libstore/download.cc
@@ -614,6 +614,22 @@ struct CurlDownloader : public Downloader
        writeFull(wakeupPipe.writeSide.get(), " ");
    }

+#ifdef ENABLE_S3
+    std::tuple<std::string, std::string, Store::Params> parseS3Uri(std::string uri)
+    {
+        auto [path, params] = splitUriAndParams(uri);
+
+        auto slash = path.find('/', 5); // 5 is the length of "s3://" prefix
+            if (slash == std::string::npos)
+                throw nix::Error("bad S3 URI '%s'", path);
+
+        std::string bucketName(path, 5, slash - 5);
+        std::string key(path, slash + 1);
+
+        return {bucketName, key, params};
+    }
+#endif
+
    void enqueueDownload(const DownloadRequest & request,
        Callback<DownloadResult> callback) override
    {
@@ -622,12 +638,15 @@ struct CurlDownloader : public Downloader
            // FIXME: do this on a worker thread
            try {
 #ifdef ENABLE_S3
-                S3Helper s3Helper("", Aws::Region::US_EAST_1, "", ""); // FIXME: make configurable
-                auto slash = request.uri.find('/', 5);
-                if (slash == std::string::npos)
-                    throw nix::Error("bad S3 URI '%s'", request.uri);
-                std::string bucketName(request.uri, 5, slash - 5);
-                std::string key(request.uri, slash + 1);
+                auto [bucketName, key, params] = parseS3Uri(request.uri);
+
+                std::string profile = get(params, "profile", "");
+                std::string region = get(params, "region", Aws::Region::US_EAST_1);
+                std::string scheme = get(params, "scheme", "");
+                std::string endpoint = get(params, "endpoint", "");
+
+                S3Helper s3Helper(profile, region, scheme, endpoint);
+
                // FIXME: implement ETag
                auto s3Res = s3Helper.getObject(bucketName, key);
                DownloadResult res;
--- a/src/libstore/gc.cc
+++ b/src/libstore/gc.cc
@@ -129,8 +129,8 @@ Path LocalFSStore::addPermRoot(const Path & _storePath,
       check if the root is in a directory in or linked from the
       gcroots directory. */
    if (settings.checkRootReachability) {
-        Roots roots = findRoots();
-        if (roots.find(gcRoot) == roots.end())
+        Roots roots = findRoots(false);
+        if (roots[storePath].count(gcRoot) == 0)
            printError(
                format(
                    "warning: '%1%' is not in a directory where the garbage collector looks for roots; "
@@ -197,10 +197,11 @@ void LocalStore::addTempRoot(const Path & path)
 }


-std::set<std::pair<pid_t, Path>> LocalStore::readTempRoots(FDs & fds)
-{
-    std::set<std::pair<pid_t, Path>> tempRoots;
+static std::string censored = "{censored}";

+
+void LocalStore::findTempRoots(FDs & fds, Roots & tempRoots, bool censor)
+{
    /* Read the `temproots' directory for per-process temporary root
       files. */
    for (auto & i : readDirectory(tempRootsDir)) {
@@ -250,14 +251,12 @@ std::set<std::pair<pid_t, Path>> LocalStore::readTempRoots(FDs & fds)
            Path root(contents, pos, end - pos);
            debug("got temporary root '%s'", root);
            assertStorePath(root);
-            tempRoots.emplace(pid, root);
+            tempRoots[root].emplace(censor ? censored : fmt("{temp:%d}", pid));
            pos = end + 1;
        }

        fds.push_back(fd); /* keep open */
    }
-
-    return tempRoots;
 }


@@ -266,7 +265,7 @@ void LocalStore::findRoots(const Path & path, unsigned char type, Roots & roots)
    auto foundRoot = [&](const Path & path, const Path & target) {
        Path storePath = toStorePath(target);
        if (isStorePath(storePath) && isValidPath(storePath))
-            roots[path] = storePath;
+            roots[storePath].emplace(path);
        else
            printInfo(format("skipping invalid root from '%1%' to '%2%'") % path % storePath);
    };
@@ -306,7 +305,7 @@ void LocalStore::findRoots(const Path & path, unsigned char type, Roots & roots)
        else if (type == DT_REG) {
            Path storePath = storeDir + "/" + baseNameOf(path);
            if (isStorePath(storePath) && isValidPath(storePath))
-                roots[path] = storePath;
+                roots[storePath].emplace(path);
        }

    }
@@ -321,10 +320,8 @@ void LocalStore::findRoots(const Path & path, unsigned char type, Roots & roots)
 }


-Roots LocalStore::findRootsNoTemp()
+void LocalStore::findRootsNoTemp(Roots & roots, bool censor)
 {
-    Roots roots;
-
    /* Process direct roots in {gcroots,profiles}. */
    findRoots(stateDir + "/" + gcRootsDir, DT_UNKNOWN, roots);
    findRoots(stateDir + "/profiles", DT_UNKNOWN, roots);
@@ -333,32 +330,22 @@ Roots LocalStore::findRootsNoTemp()
       NIX_ROOT_FINDER environment variable.  This is typically used
       to add running programs to the set of roots (to prevent them
       from being garbage collected). */
-    size_t n = 0;
-    for (auto & root : findRuntimeRoots())
-        roots[fmt("{memory:%d}", n++)] = root;
-
-    return roots;
+    findRuntimeRoots(roots, censor);
 }


-Roots LocalStore::findRoots()
+Roots LocalStore::findRoots(bool censor)
 {
-    Roots roots = findRootsNoTemp();
+    Roots roots;
+    findRootsNoTemp(roots, censor);

    FDs fds;
-    pid_t prev = -1;
-    size_t n = 0;
-    for (auto & root : readTempRoots(fds)) {
-        if (prev != root.first) n = 0;
-        prev = root.first;
-        roots[fmt("{temp:%d:%d}", root.first, n++)] = root.second;
-    }
+    findTempRoots(fds, roots, censor);

    return roots;
 }

-
-static void readProcLink(const string & file, StringSet & paths)
+static void readProcLink(const string & file, Roots & roots)
 {
    /* 64 is the starting buffer size gnu readlink uses... */
    auto bufsiz = ssize_t{64};
@@ -377,8 +364,8 @@ try_again:
        goto try_again;
    }
    if (res > 0 && buf[0] == '/')
-        paths.emplace(static_cast<char *>(buf), res);
-    return;
+        roots[std::string(static_cast<char *>(buf), res)]
+            .emplace(file);
 }

 static string quoteRegexChars(const string & raw)
@@ -387,20 +374,20 @@ static string quoteRegexChars(const string & raw)
    return std::regex_replace(raw, specialRegex, R"(\$&)");
 }

-static void readFileRoots(const char * path, StringSet & paths)
+static void readFileRoots(const char * path, Roots & roots)
 {
    try {
-        paths.emplace(readFile(path));
+        roots[readFile(path)].emplace(path);
    } catch (SysError & e) {
        if (e.errNo != ENOENT && e.errNo != EACCES)
            throw;
    }
 }

-PathSet LocalStore::findRuntimeRoots()
+void LocalStore::findRuntimeRoots(Roots & roots, bool censor)
 {
-    PathSet roots;
-    StringSet paths;
+    Roots unchecked;
+
    auto procDir = AutoCloseDir{opendir("/proc")};
    if (procDir) {
        struct dirent * ent;
@@ -410,10 +397,10 @@ PathSet LocalStore::findRuntimeRoots()
        while (errno = 0, ent = readdir(procDir.get())) {
            checkInterrupt();
            if (std::regex_match(ent->d_name, digitsRegex)) {
-                readProcLink((format("/proc/%1%/exe") % ent->d_name).str(), paths);
-                readProcLink((format("/proc/%1%/cwd") % ent->d_name).str(), paths);
+                readProcLink(fmt("/proc/%s/exe" ,ent->d_name), unchecked);
+                readProcLink(fmt("/proc/%s/cwd", ent->d_name), unchecked);

-                auto fdStr = (format("/proc/%1%/fd") % ent->d_name).str();
+                auto fdStr = fmt("/proc/%s/fd", ent->d_name);
                auto fdDir = AutoCloseDir(opendir(fdStr.c_str()));
                if (!fdDir) {
                    if (errno == ENOENT || errno == EACCES)
@@ -422,9 +409,8 @@ PathSet LocalStore::findRuntimeRoots()
                }
                struct dirent * fd_ent;
                while (errno = 0, fd_ent = readdir(fdDir.get())) {
-                    if (fd_ent->d_name[0] != '.') {
-                        readProcLink((format("%1%/%2%") % fdStr % fd_ent->d_name).str(), paths);
-                    }
+                    if (fd_ent->d_name[0] != '.')
+                        readProcLink(fmt("%s/%s", fdStr, fd_ent->d_name), unchecked);
                }
                if (errno) {
                    if (errno == ESRCH)
@@ -434,18 +420,19 @@ PathSet LocalStore::findRuntimeRoots()
                fdDir.reset();

                try {
-                    auto mapLines =
-                        tokenizeString<std::vector<string>>(readFile((format("/proc/%1%/maps") % ent->d_name).str(), true), "\n");
-                    for (const auto& line : mapLines) {
+                    auto mapFile = fmt("/proc/%s/maps", ent->d_name);
+                    auto mapLines = tokenizeString<std::vector<string>>(readFile(mapFile, true), "\n");
+                    for (const auto & line : mapLines) {
                        auto match = std::smatch{};
                        if (std::regex_match(line, match, mapRegex))
-                            paths.emplace(match[1]);
+                            unchecked[match[1]].emplace(mapFile);
                    }

-                    auto envString = readFile((format("/proc/%1%/environ") % ent->d_name).str(), true);
+                    auto envFile = fmt("/proc/%s/environ", ent->d_name);
+                    auto envString = readFile(envFile, true);
                    auto env_end = std::sregex_iterator{};
                    for (auto i = std::sregex_iterator{envString.begin(), envString.end(), storePathRegex}; i != env_end; ++i)
-                        paths.emplace(i->str());
+                        unchecked[i->str()].emplace(envFile);
                } catch (SysError & e) {
                    if (errno == ENOENT || errno == EACCES || errno == ESRCH)
                        continue;
@@ -465,7 +452,7 @@ PathSet LocalStore::findRuntimeRoots()
        for (const auto & line : lsofLines) {
            std::smatch match;
            if (std::regex_match(line, match, lsofRegex))
-                paths.emplace(match[1]);
+                unchecked[match[1]].emplace("{lsof}");
        }
    } catch (ExecError & e) {
        /* lsof not installed, lsof failed */
@@ -473,21 +460,23 @@ PathSet LocalStore::findRuntimeRoots()
 #endif

 #if defined(__linux__)
-    readFileRoots("/proc/sys/kernel/modprobe", paths);
-    readFileRoots("/proc/sys/kernel/fbsplash", paths);
-    readFileRoots("/proc/sys/kernel/poweroff_cmd", paths);
+    readFileRoots("/proc/sys/kernel/modprobe", unchecked);
+    readFileRoots("/proc/sys/kernel/fbsplash", unchecked);
+    readFileRoots("/proc/sys/kernel/poweroff_cmd", unchecked);
 #endif

-    for (auto & i : paths)
-        if (isInStore(i)) {
-            Path path = toStorePath(i);
-            if (roots.find(path) == roots.end() && isStorePath(path) && isValidPath(path)) {
+    for (auto & [target, links] : unchecked) {
+        if (isInStore(target)) {
+            Path path = toStorePath(target);
+            if (isStorePath(path) && isValidPath(path)) {
                debug(format("got additional root '%1%'") % path);
-                roots.insert(path);
+                if (censor)
+                    roots[path].insert(censored);
+                else
+                    roots[path].insert(links.begin(), links.end());
            }
        }
-
-    return roots;
+    }
 }


@@ -754,16 +743,20 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
    /* Find the roots.  Since we've grabbed the GC lock, the set of
       permanent roots cannot increase now. */
    printError(format("finding garbage collector roots..."));
-    Roots rootMap = options.ignoreLiveness ? Roots() : findRootsNoTemp();
+    Roots rootMap;
+    if (!options.ignoreLiveness)
+        findRootsNoTemp(rootMap, true);

-    for (auto & i : rootMap) state.roots.insert(i.second);
+    for (auto & i : rootMap) state.roots.insert(i.first);

    /* Read the temporary roots.  This acquires read locks on all
       per-process temporary root files.  So after this point no paths
       can be added to the set of temporary roots. */
    FDs fds;
-    for (auto & root : readTempRoots(fds))
-        state.tempRoots.insert(root.second);
+    Roots tempRoots;
+    findTempRoots(fds, tempRoots, true);
+    for (auto & root : tempRoots)
+        state.tempRoots.insert(root.first);
    state.roots.insert(state.tempRoots.begin(), state.tempRoots.end());

    /* After this point the set of roots or temporary roots cannot
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -187,28 +187,17 @@ struct LegacySSHStore : public Store
        copyNAR(conn->from, sink);
    }

-    PathSet queryAllValidPaths() override { unsupported(); }
-
-    void queryReferrers(const Path & path, PathSet & referrers) override
-    { unsupported(); }
-
-    PathSet queryDerivationOutputs(const Path & path) override
-    { unsupported(); }
-
-    StringSet queryDerivationOutputNames(const Path & path) override
-    { unsupported(); }
-
    Path queryPathFromHashPart(const string & hashPart) override
-    { unsupported(); }
+    { unsupported("queryPathFromHashPart"); }

    Path addToStore(const string & name, const Path & srcPath,
        bool recursive, HashType hashAlgo,
        PathFilter & filter, RepairFlag repair) override
-    { unsupported(); }
+    { unsupported("addToStore"); }

    Path addTextToStore(const string & name, const string & s,
        const PathSet & references, RepairFlag repair) override
-    { unsupported(); }
+    { unsupported("addTextToStore"); }

    BuildResult buildDerivation(const Path & drvPath, const BasicDerivation & drv,
        BuildMode buildMode) override
@@ -242,25 +231,7 @@ struct LegacySSHStore : public Store
    }

    void ensurePath(const Path & path) override
-    { unsupported(); }
-
-    void addTempRoot(const Path & path) override
-    { unsupported(); }
-
-    void addIndirectRoot(const Path & path) override
-    { unsupported(); }
-
-    Roots findRoots() override
-    { unsupported(); }
-
-    void collectGarbage(const GCOptions & options, GCResults & results) override
-    { unsupported(); }
-
-    ref<FSAccessor> getFSAccessor() override
-    { unsupported(); }
-
-    void addSignatures(const Path & storePath, const StringSet & sigs) override
-    { unsupported(); }
+    { unsupported("ensurePath"); }

    void computeFSClosure(const PathSet & paths,
        PathSet & out, bool flipDirection = false,
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -366,8 +366,6 @@ void LocalStore::makeStoreWritable()
        throw SysError("getting info about the Nix store mount point");

    if (stat.f_flag & ST_RDONLY) {
-        saveMountNamespace();
-
        if (unshare(CLONE_NEWNS) == -1)
            throw SysError("setting up a private mount namespace");

--- a/src/libstore/local-store.hh
+++ b/src/libstore/local-store.hh
@@ -180,11 +180,11 @@ private:
    typedef std::shared_ptr<AutoCloseFD> FDPtr;
    typedef list<FDPtr> FDs;

-    std::set<std::pair<pid_t, Path>> readTempRoots(FDs & fds);
+    void findTempRoots(FDs & fds, Roots & roots, bool censor);

 public:

-    Roots findRoots() override;
+    Roots findRoots(bool censor) override;

    void collectGarbage(const GCOptions & options, GCResults & results) override;

@@ -267,9 +267,9 @@ private:

    void findRoots(const Path & path, unsigned char type, Roots & roots);

-    Roots findRootsNoTemp();
+    void findRootsNoTemp(Roots & roots, bool censor);

-    PathSet findRuntimeRoots();
+    void findRuntimeRoots(Roots & roots, bool censor);

    void removeUnusedLinks(const GCState & state);

--- a/src/libstore/machines.cc
+++ b/src/libstore/machines.cc
@@ -89,10 +89,11 @@ void parseMachines(const std::string & s, Machines & machines)

 Machines getMachines()
 {
-    Machines machines;
-
-    parseMachines(settings.builders, machines);
-
+    static auto machines = [&]() {
+        Machines machines;
+        parseMachines(settings.builders, machines);
+        return machines;
+    }();
    return machines;
 }

--- a/src/libstore/nix-store.pc.in
+++ b/src/libstore/nix-store.pc.in
@@ -6,4 +6,4 @@ Name: Nix
 Description: Nix Package Manager
 Version: @PACKAGE_VERSION@
 Libs: -L${libdir} -lnixstore -lnixutil
-Cflags: -I${includedir}/nix -std=c++14
+Cflags: -I${includedir}/nix -std=c++17
--- a/src/libstore/parsed-derivations.cc
+++ b/src/libstore/parsed-derivations.cc
@@ -16,7 +16,7 @@ ParsedDerivation::ParsedDerivation(const Path & drvPath, BasicDerivation & drv)
    }
 }

-std::experimental::optional<std::string> ParsedDerivation::getStringAttr(const std::string & name) const
+std::optional<std::string> ParsedDerivation::getStringAttr(const std::string & name) const
 {
    if (structuredAttrs) {
        auto i = structuredAttrs->find(name);
@@ -56,7 +56,7 @@ bool ParsedDerivation::getBoolAttr(const std::string & name, bool def) const
    }
 }

-std::experimental::optional<Strings> ParsedDerivation::getStringsAttr(const std::string & name) const
+std::optional<Strings> ParsedDerivation::getStringsAttr(const std::string & name) const
 {
    if (structuredAttrs) {
        auto i = structuredAttrs->find(name);
--- a/src/libstore/parsed-derivations.hh
+++ b/src/libstore/parsed-derivations.hh
@@ -8,22 +8,22 @@ class ParsedDerivation
 {
    Path drvPath;
    BasicDerivation & drv;
-    std::experimental::optional<nlohmann::json> structuredAttrs;
+    std::optional<nlohmann::json> structuredAttrs;

 public:

    ParsedDerivation(const Path & drvPath, BasicDerivation & drv);

-    const std::experimental::optional<nlohmann::json> & getStructuredAttrs() const
+    const std::optional<nlohmann::json> & getStructuredAttrs() const
    {
        return structuredAttrs;
    }

-    std::experimental::optional<std::string> getStringAttr(const std::string & name) const;
+    std::optional<std::string> getStringAttr(const std::string & name) const;

    bool getBoolAttr(const std::string & name, bool def = false) const;

-    std::experimental::optional<Strings> getStringsAttr(const std::string & name) const;
+    std::optional<Strings> getStringsAttr(const std::string & name) const;

    StringSet getRequiredSystemFeatures() const;

--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -596,7 +596,7 @@ void RemoteStore::syncWithGC()
 }


-Roots RemoteStore::findRoots()
+Roots RemoteStore::findRoots(bool censor)
 {
    auto conn(getConnection());
    conn->to << wopFindRoots;
@@ -606,7 +606,7 @@ Roots RemoteStore::findRoots()
    while (count--) {
        Path link = readString(conn->from);
        Path target = readStorePath(*this, conn->from);
-        result[link] = target;
+        result[target].emplace(link);
    }
    return result;
 }
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -82,7 +82,7 @@ public:

    void syncWithGC() override;

-    Roots findRoots() override;
+    Roots findRoots(bool censor) override;

    void collectGarbage(const GCOptions & options, GCResults & results) override;

@@ -149,7 +149,7 @@ public:
 private:

    ref<RemoteStore::Connection> openConnection() override;
-    std::experimental::optional<std::string> path;
+    std::optional<std::string> path;
 };


--- a/src/libstore/s3-binary-cache-store.cc
+++ b/src/libstore/s3-binary-cache-store.cc
@@ -126,6 +126,7 @@ ref<Aws::Client::ClientConfiguration> S3Helper::makeConfig(const string & region
        res->endpointOverride = endpoint;
    }
    res->requestTimeoutMs = 600 * 1000;
+    res->connectTimeoutMs = 5 * 1000;
    res->retryStrategy = std::make_shared<RetryStrategy>();
    res->caFile = settings.caFile;
    return res;
--- a/src/libstore/ssh.cc
+++ b/src/libstore/ssh.cc
@@ -1,5 +1,4 @@
 #include "ssh.hh"
-#include "affinity.hh"

 namespace nix {

@@ -35,9 +34,7 @@ std::unique_ptr<SSHMaster::Connection> SSHMaster::startCommand(const std::string

    auto conn = std::make_unique<Connection>();
    conn->sshPid = startProcess([&]() {
-        restoreAffinity();
        restoreSignals();
-        restoreMountNamespace();

        close(in.writeSide.get());
        close(out.readSide.get());
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -562,10 +562,10 @@ void Store::buildPaths(const PathSet & paths, BuildMode buildMode)
 {
    for (auto & path : paths)
        if (isDerivation(path))
-            unsupported();
+            unsupported("buildPaths");

    if (queryValidPaths(paths).size() != paths.size())
-        unsupported();
+        unsupported("buildPaths");
 }


@@ -842,12 +842,11 @@ namespace nix {

 RegisterStoreImplementation::Implementations * RegisterStoreImplementation::implementations = 0;

-
-ref<Store> openStore(const std::string & uri_,
-    const Store::Params & extraParams)
+/* Split URI into protocol+hierarchy part and its parameter set. */
+std::pair<std::string, Store::Params> splitUriAndParams(const std::string & uri_)
 {
    auto uri(uri_);
-    Store::Params params(extraParams);
+    Store::Params params;
    auto q = uri.find('?');
    if (q != std::string::npos) {
        for (auto s : tokenizeString<Strings>(uri.substr(q + 1), "&")) {
@@ -873,6 +872,15 @@ ref<Store> openStore(const std::string & uri_,
        }
        uri = uri_.substr(0, q);
    }
+    return {uri, params};
+}
+
+ref<Store> openStore(const std::string & uri_,
+    const Store::Params & extraParams)
+{
+    auto [uri, uriParams] = splitUriAndParams(uri_);
+    auto params = extraParams;
+    params.insert(uriParams.begin(), uriParams.end());

    for (auto fun : *RegisterStoreImplementation::implementations) {
        auto store = fun(uri, params);
--- a/src/libstore/store-api.hh
+++ b/src/libstore/store-api.hh
@@ -11,6 +11,8 @@
 #include <atomic>
 #include <limits>
 #include <map>
+#include <unordered_map>
+#include <unordered_set>
 #include <memory>
 #include <string>

@@ -47,7 +49,7 @@ const size_t storePathHashLen = 32; // i.e. 160 bits
 const uint32_t exportMagic = 0x4558494e;


-typedef std::map<Path, Path> Roots;
+typedef std::unordered_map<Path, std::unordered_set<std::string>> Roots;


 struct GCOptions
@@ -349,7 +351,8 @@ public:
       (i.e. you'll get /nix/store/<hash> rather than
       /nix/store/<hash>-<name>). Use queryPathInfo() to obtain the
       full store path. */
-    virtual PathSet queryAllValidPaths() = 0;
+    virtual PathSet queryAllValidPaths()
+    { unsupported("queryAllValidPaths"); }

    /* Query information about a valid path. It is permitted to omit
       the name part of the store path. */
@@ -368,8 +371,8 @@ public:

    /* Queries the set of incoming FS references for a store path.
       The result is not cleared. */
-    virtual void queryReferrers(const Path & path,
-        PathSet & referrers) = 0;
+    virtual void queryReferrers(const Path & path, PathSet & referrers)
+    { unsupported("queryReferrers"); }

    /* Return all currently valid derivations that have `path' as an
       output.  (Note that the result of `queryDeriver()' is the
@@ -378,10 +381,12 @@ public:
    virtual PathSet queryValidDerivers(const Path & path) { return {}; };

    /* Query the outputs of the derivation denoted by `path'. */
-    virtual PathSet queryDerivationOutputs(const Path & path) = 0;
+    virtual PathSet queryDerivationOutputs(const Path & path)
+    { unsupported("queryDerivationOutputs"); }

    /* Query the output names of the derivation denoted by `path'. */
-    virtual StringSet queryDerivationOutputNames(const Path & path) = 0;
+    virtual StringSet queryDerivationOutputNames(const Path & path)
+    { unsupported("queryDerivationOutputNames"); }

    /* Query the full store path given the hash part of a valid store
       path, or "" if the path doesn't exist. */
@@ -447,14 +452,16 @@ public:

    /* Add a store path as a temporary root of the garbage collector.
       The root disappears as soon as we exit. */
-    virtual void addTempRoot(const Path & path) = 0;
+    virtual void addTempRoot(const Path & path)
+    { unsupported("addTempRoot"); }

    /* Add an indirect root, which is merely a symlink to `path' from
       /nix/var/nix/gcroots/auto/<hash of `path'>.  `path' is supposed
       to be a symlink to a store path.  The garbage collector will
       automatically remove the indirect root when it finds that
       `path' has disappeared. */
-    virtual void addIndirectRoot(const Path & path) = 0;
+    virtual void addIndirectRoot(const Path & path)
+    { unsupported("addIndirectRoot"); }

    /* Acquire the global GC lock, then immediately release it.  This
       function must be called after registering a new permanent root,
@@ -478,11 +485,15 @@ public:

    /* Find the roots of the garbage collector.  Each root is a pair
       (link, storepath) where `link' is the path of the symlink
-       outside of the Nix store that point to `storePath'.  */
-    virtual Roots findRoots() = 0;
+       outside of the Nix store that point to `storePath'. If
+       'censor' is true, privacy-sensitive information about roots
+       found in /proc is censored. */
+    virtual Roots findRoots(bool censor)
+    { unsupported("findRoots"); }

    /* Perform a garbage collection. */
-    virtual void collectGarbage(const GCOptions & options, GCResults & results) = 0;
+    virtual void collectGarbage(const GCOptions & options, GCResults & results)
+    { unsupported("collectGarbage"); }

    /* Return a string representing information about the path that
       can be loaded into the database using `nix-store --load-db' or
@@ -513,11 +524,13 @@ public:
    virtual bool verifyStore(bool checkContents, RepairFlag repair = NoRepair) { return false; };

    /* Return an object to access files in the Nix store. */
-    virtual ref<FSAccessor> getFSAccessor() = 0;
+    virtual ref<FSAccessor> getFSAccessor()
+    { unsupported("getFSAccessor"); }

    /* Add signatures to the specified store path. The signatures are
       not verified. */
-    virtual void addSignatures(const Path & storePath, const StringSet & sigs) = 0;
+    virtual void addSignatures(const Path & storePath, const StringSet & sigs)
+    { unsupported("addSignatures"); }

    /* Utility functions. */

@@ -620,9 +633,9 @@ protected:
    Stats stats;

    /* Unsupported methods. */
-    [[noreturn]] void unsupported()
+    [[noreturn]] void unsupported(const std::string & op)
    {
-        throw Unsupported("requested operation is not supported by store '%s'", getUri());
+        throw Unsupported("operation '%s' is not supported by store '%s'", op, getUri());
    }

 };
@@ -789,4 +802,8 @@ ValidPathInfo decodeValidPathInfo(std::istream & str,
   for paths created by makeFixedOutputPath() / addToStore(). */
 std::string makeFixedOutputCA(bool recursive, const Hash & hash);

+
+/* Split URI into protocol+hierarchy part and its parameter set. */
+std::pair<std::string, Store::Params> splitUriAndParams(const std::string & uri);
+
 }
--- a/src/libutil/archive.cc
+++ b/src/libutil/archive.cc
@@ -331,7 +331,7 @@ struct RestoreSink : ParseSink
               filesystem doesn't support preallocation (e.g. on
               OpenSolaris).  Since preallocation is just an
               optimisation, ignore it. */
-            if (errno && errno != EINVAL)
+            if (errno && errno != EINVAL && errno != EOPNOTSUPP && errno != ENOSYS)
                throw SysError(format("preallocating file of %1% bytes") % len);
        }
 #endif
--- a/src/libutil/lru-cache.hh
+++ b/src/libutil/lru-cache.hh
@@ -2,7 +2,7 @@

 #include <map>
 #include <list>
-#include <experimental/optional>
+#include <optional>

 namespace nix {

@@ -64,7 +64,7 @@ public:

    /* Look up an item in the cache. If it exists, it becomes the most
       recently used item. */
-    std::experimental::optional<Value> get(const Key & key)
+    std::optional<Value> get(const Key & key)
    {
        auto i = data.find(key);
        if (i == data.end()) return {};
--- a/src/libutil/serialise.cc
+++ b/src/libutil/serialise.cc
@@ -171,7 +171,7 @@ std::unique_ptr<Source> sinkToSource(

        std::function<void(Sink &)> fun;
        std::function<void()> eof;
-        std::experimental::optional<coro_t::pull_type> coro;
+        std::optional<coro_t::pull_type> coro;
        bool started = false;

        SinkToSource(std::function<void(Sink &)> fun, std::function<void()> eof)
--- a/src/libutil/util.cc
+++ b/src/libutil/util.cc
@@ -936,8 +936,6 @@ pid_t startProcess(std::function<void()> fun, const ProcessOptions & options)
                throw SysError("setting death signal");
 #endif
            restoreAffinity();
-            if (options.restoreMountNamespace)
-                restoreMountNamespace();
            fun();
        } catch (std::exception & e) {
            try {
@@ -967,7 +965,7 @@ std::vector<char *> stringsToCharPtrs(const Strings & ss)


 string runProgram(Path program, bool searchPath, const Strings & args,
-    const std::experimental::optional<std::string> & input)
+    const std::optional<std::string> & input)
 {
    RunOptions opts(program, args);
    opts.searchPath = searchPath;
@@ -1506,26 +1504,4 @@ std::unique_ptr<InterruptCallback> createInterruptCallback(std::function<void()>
    return std::unique_ptr<InterruptCallback>(res.release());
 }

-static AutoCloseFD fdSavedMountNamespace;
-
-void saveMountNamespace()
-{
-#if __linux__
-    std::once_flag done;
-    std::call_once(done, []() {
-        fdSavedMountNamespace = open("/proc/self/ns/mnt", O_RDONLY);
-        if (!fdSavedMountNamespace)
-            throw SysError("saving parent mount namespace");
-    });
-#endif
-}
-
-void restoreMountNamespace()
-{
-#if __linux__
-    if (fdSavedMountNamespace && setns(fdSavedMountNamespace.get(), CLONE_NEWNS) == -1)
-        throw SysError("restoring parent mount namespace");
-#endif
-}
-
 }
--- a/src/libutil/util.hh
+++ b/src/libutil/util.hh
@@ -14,7 +14,7 @@
 #include <cstdio>
 #include <map>
 #include <sstream>
-#include <experimental/optional>
+#include <optional>
 #include <future>

 #ifndef HAVE_STRUCT_DIRENT_D_TYPE
@@ -250,7 +250,6 @@ struct ProcessOptions
    bool dieWithParent = true;
    bool runExitHandlers = false;
    bool allowVfork = true;
-    bool restoreMountNamespace = true;
 };

 pid_t startProcess(std::function<void()> fun, const ProcessOptions & options = ProcessOptions());
@@ -260,14 +259,14 @@ pid_t startProcess(std::function<void()> fun, const ProcessOptions & options = P
   shell backtick operator). */
 string runProgram(Path program, bool searchPath = false,
    const Strings & args = Strings(),
-    const std::experimental::optional<std::string> & input = {});
+    const std::optional<std::string> & input = {});

 struct RunOptions
 {
    Path program;
    bool searchPath = true;
    Strings args;
-    std::experimental::optional<std::string> input;
+    std::optional<std::string> input;
    Source * standardIn = nullptr;
    Sink * standardOut = nullptr;
    bool _killStderr = false;
@@ -515,13 +514,4 @@ typedef std::function<bool(const Path & path)> PathFilter;
 extern PathFilter defaultPathFilter;


-/* Save the current mount namespace. Ignored if called more than
-   once. */
-void saveMountNamespace();
-
-/* Restore the mount namespace saved by saveMountNamespace(). Ignored
-   if saveMountNamespace() was never called. */
-void restoreMountNamespace();
-
-
 }
--- a/src/nix-build/nix-build.cc
+++ b/src/nix-build/nix-build.cc
@@ -401,6 +401,8 @@ static void _main(int argc, char * * argv)
            } else
                env[var.first] = var.second;

+        restoreAffinity();
+
        /* Run a shell using the derivation's environment.  For
           convenience, source $stdenv/setup to setup additional
           environment variables and shell functions.  Also don't
@@ -444,9 +446,7 @@ static void _main(int argc, char * * argv)

        auto argPtrs = stringsToCharPtrs(args);

-        restoreAffinity();
        restoreSignals();
-        restoreMountNamespace();

        execvp(shell.c_str(), argPtrs.data());

--- a/src/nix-daemon/nix-daemon.cc
+++ b/src/nix-daemon/nix-daemon.cc
@@ -475,11 +475,19 @@ static void performOp(TunnelLogger * logger, ref<Store> store,

    case wopFindRoots: {
        logger->startWork();
-        Roots roots = store->findRoots();
+        Roots roots = store->findRoots(!trusted);
        logger->stopWork();
-        to << roots.size();
+
+        size_t size = 0;
        for (auto & i : roots)
-            to << i.first << i.second;
+            size += i.second.size();
+
+        to << size;
+
+        for (auto & [target, links] : roots)
+            for (auto & link : links)
+                to << link << target;
+
        break;
    }

--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -427,10 +427,11 @@ static void opQuery(Strings opFlags, Strings opArgs)
                    maybeUseOutputs(store->followLinksToStorePath(i), useOutput, forceRealise),
                    referrers, true, settings.gcKeepOutputs, settings.gcKeepDerivations);
            }
-            Roots roots = store->findRoots();
-            for (auto & i : roots)
-                if (referrers.find(i.second) != referrers.end())
-                    cout << format("%1%\n") % i.first;
+            Roots roots = store->findRoots(false);
+            for (auto & [target, links] : roots)
+                if (referrers.find(target) != referrers.end())
+                    for (auto & link : links)
+                        cout << format("%1% -> %2%\n") % link % target;
            break;
        }

@@ -485,11 +486,16 @@ static void opReadLog(Strings opFlags, Strings opArgs)
 static void opDumpDB(Strings opFlags, Strings opArgs)
 {
    if (!opFlags.empty()) throw UsageError("unknown flag");
-    if (!opArgs.empty())
-        throw UsageError("no arguments expected");
-    PathSet validPaths = store->queryAllValidPaths();
-    for (auto & i : validPaths)
-        cout << store->makeValidityRegistration({i}, true, true);
+    if (!opArgs.empty()) {
+        for (auto & i : opArgs)
+            i = store->followLinksToStorePath(i);
+        for (auto & i : opArgs)
+            cout << store->makeValidityRegistration({i}, true, true);
+    } else {
+        PathSet validPaths = store->queryAllValidPaths();
+        for (auto & i : validPaths)
+            cout << store->makeValidityRegistration({i}, true, true);
+    }
 }


@@ -585,9 +591,14 @@ static void opGC(Strings opFlags, Strings opArgs)
    if (!opArgs.empty()) throw UsageError("no arguments expected");

    if (printRoots) {
-        Roots roots = store->findRoots();
-        for (auto & i : roots)
-            cout << i.first << " -> " << i.second << std::endl;
+        Roots roots = store->findRoots(false);
+        std::set<std::pair<Path, Path>> roots2;
+        // Transpose and sort the roots.
+        for (auto & [target, links] : roots)
+            for (auto & link : links)
+                roots2.emplace(link, target);
+        for (auto & [link, target] : roots2)
+            std::cout << link << " -> " << target << "\n";
    }

    else {
--- a/src/nix/add-to-store.cc
+++ b/src/nix/add-to-store.cc
@@ -8,7 +8,7 @@ using namespace nix;
 struct CmdAddToStore : MixDryRun, StoreCommand
 {
    Path path;
-    std::experimental::optional<std::string> namePart;
+    std::optional<std::string> namePart;

    CmdAddToStore()
    {
--- a/src/nix/edit.cc
+++ b/src/nix/edit.cc
@@ -3,7 +3,6 @@
 #include "eval.hh"
 #include "attr-path.hh"
 #include "progress-bar.hh"
-#include "affinity.hh"

 #include <unistd.h>

@@ -73,10 +72,6 @@ struct CmdEdit : InstallableCommand

        stopProgressBar();

-        restoreAffinity();
-        restoreSignals();
-        restoreMountNamespace();
-
        execvp(args.front().c_str(), stringsToCharPtrs(args).data());

        throw SysError("cannot run editor '%s'", editor);
--- a/src/nix/repl.cc
+++ b/src/nix/repl.cc
@@ -337,8 +337,6 @@ static int runProgram(const string & program, const Strings & args)
    if (pid == -1) throw SysError("forking");
    if (pid == 0) {
        restoreAffinity();
-        restoreSignals();
-        restoreMountNamespace();
        execvp(program.c_str(), stringsToCharPtrs(args2).data());
        _exit(1);
    }
--- a/src/nix/run.cc
+++ b/src/nix/run.cc
@@ -153,9 +153,9 @@ struct CmdRun : InstallablesCommand

        stopProgressBar();

-        restoreAffinity();
        restoreSignals();
-        restoreMountNamespace();
+
+        restoreAffinity();

        /* If this is a diverted store (i.e. its "logical" location
           (typically /nix/store) differs from its "physical" location
--- a/tests/gc.sh
+++ b/tests/gc.sh
@@ -7,7 +7,7 @@ outPath=$(nix-store -rvv "$drvPath")
 rm -f "$NIX_STATE_DIR"/gcroots/foo
 ln -sf $outPath "$NIX_STATE_DIR"/gcroots/foo

-[ "$(nix-store -q --roots $outPath)" = "$NIX_STATE_DIR"/gcroots/foo ]
+[ "$(nix-store -q --roots $outPath)" = "$NIX_STATE_DIR/gcroots/foo -> $outPath" ]

 nix-store --gc --print-roots | grep $outPath
 nix-store --gc --print-live | grep $outPath
--- a/tests/lang/eval-okay-context-introspection.exp
+++ b/tests/lang/eval-okay-context-introspection.exp
@@ -0,0 +1 @@
+true
--- a/tests/lang/eval-okay-context-introspection.nix
+++ b/tests/lang/eval-okay-context-introspection.nix
@@ -0,0 +1,24 @@
+let
+  drv = derivation {
+    name = "fail";
+    builder = "/bin/false";
+    system = "x86_64-linux";
+    outputs = [ "out" "foo" ];
+  };
+
+  path = "${./eval-okay-context-introspection.nix}";
+
+  desired-context = {
+    "${builtins.unsafeDiscardStringContext path}" = {
+      path = true;
+    };
+    "${builtins.unsafeDiscardStringContext drv.drvPath}" = {
+      outputs = [ "foo" "out" ];
+      allOutputs = true;
+    };
+  };
+
+  legit-context = builtins.getContext "${path}${drv.outPath}${drv.foo.outPath}${drv.drvPath}";
+
+  constructed-context = builtins.getContext (builtins.appendContext "" desired-context);
+in legit-context == constructed-context
--- a/tests/lang/eval-okay-types.exp
+++ b/tests/lang/eval-okay-types.exp
@@ -1 +1 @@
-[ true false true false true false true false true true true true true true true true true true true false true false "int" "bool" "string" "null" "set" "list" "lambda" "lambda" "lambda" "lambda" ]
+[ true false true false true false true false true true true true true true true true true true true false true true true false "int" "bool" "string" "null" "set" "list" "lambda" "lambda" "lambda" "lambda" ]
--- a/tests/lang/eval-okay-types.nix
+++ b/tests/lang/eval-okay-types.nix
@@ -20,6 +20,8 @@ with builtins;
  (isFloat (1 - 2.0))
  (isBool (true && false))
  (isBool null)
+  (isPath /nix/store)
+  (isPath ./.)
  (isAttrs { x = 123; })
  (isAttrs null)
  (typeOf (3 * 4))
--- a/1
+++ b/1
@@ -1 +0,0 @@
-2.2
Author	SHA1	Message	Date
Eelco Dolstra	a3d874175c	Add builtins.unique [WIP] This cuts ~4.5s from "nix-env -qaP -f `<nixpkgs>` --out-path" and reduces memory allocations from 7.49 to 7.16 GiB. Note that builtins.unique requires a less-than comparator function, which is a change from the 'unique' function in Nixpkgs which uses an equality function.	2019-04-12 22:47:14 +02:00
Eelco Dolstra	bb6e6923f2	Add environment variable NIX_SHOW_SYMBOLS for dumping the symbol table	2019-04-11 23:04:13 +02:00
Eelco Dolstra	41ba5135e0	primeCache(): Barf if builds are needed but not allowed Fixes #2753.	2019-04-01 21:09:49 +02:00
Eelco Dolstra	2bc6304793	getMachines(): Cache result	2019-04-01 21:09:35 +02:00
Eelco Dolstra	2f59b30251	Use Nixpkgs 19.03	2019-04-01 21:09:25 +02:00
Eelco Dolstra	f32fbf952d	Fix Bison 3.3 warning	2019-03-27 21:09:31 +01:00
Eelco Dolstra	e489f5cabf	Update eval-okay-types.exp to match #1828	2019-03-27 21:07:04 +01:00
Graham Christensen	6e9e34ea1f	Merge pull request #2744 from veprbl/patch-8 manual: mention the "channel:" shorthand for NIX_PATH	2019-03-25 21:49:48 -04:00
Dmitry Kalinkin	75ec68f93a	manual: mention the "channel:" shorthand for NIX_PATH Bumped to 15.09 because older channels, when downloaded from nixos.org, require firefox to be accessed via `pkgs.firefox`	2019-03-25 20:55:28 -04:00
Eelco Dolstra	5c05c238e6	Merge pull request #1828 from zimbatm/isPath Add isPath primop	2019-03-25 19:58:11 +01:00
Will Dietz	63e7fc5096	perl/configure.ac: fix for new version location too	2019-03-25 09:18:30 +01:00
Will Dietz	1f9c8cd68b	configure.ac: update for new version file location	2019-03-25 09:18:30 +01:00
Will Dietz	42e2d5e7b7	store-api.hh: add missing include for unordered_map	2019-03-25 09:18:30 +01:00
Will Dietz	0bebca402a	version -> .version, avoid conflict with C++20 <version>	2019-03-25 09:18:30 +01:00
Domen Kožar	6f0359012c	Merge pull request #2693 from thoughtpolice/scripts/multi-user-sandbox scripts: remove default 'sandbox = false' from multi-user installer	2019-03-24 19:45:56 +07:00
zimbatm	514b3c7f83	Add isPath primop this is added for completeness' sake since all the other possible `builtins.typeOf` results have a corresponding `builtins.is<Type>`	2019-03-24 11:36:49 +01:00
Eelco Dolstra	56f1ed5579	Merge pull request #2741 from mayflower/primop-type-desc eval: improve type description for primops and applied primops	2019-03-21 15:49:19 +01:00
Linus Heckemann	2aa89daab3	eval: improve type description for primops and applied primops This can make type errors a little easier to understand.	2019-03-21 15:31:46 +01:00
Eelco Dolstra	6a3dfcb623	Merge pull request #2739 from mayflower/builtins-doc-explicit manual: include builtins.* for globally available builtins	2019-03-21 12:24:44 +01:00
Linus Heckemann	6f093073b6	manual: include builtins.* for globally available builtins This improves searchability.	2019-03-21 09:37:22 +01:00
Eelco Dolstra	ffeabf8390	Merge pull request #2731 from nomeata/link-to-conf-builders-use-substitutes Link to `builders-use-substitutes` in chapter on distributed builds	2019-03-18 13:54:47 +01:00
Joachim Breitner	684c7fff80	Link to `builders-use-substitutes` in chapter on distributed builds fixes #2730.	2019-03-16 19:03:40 +01:00
Eelco Dolstra	806291d18c	Merge pull request #2727 from Chakerbh/master Add a 5 seconds of timeout to connecting to S3.	2019-03-15 21:25:10 +08:00
Chaker Benhamed	81a23fa7e2	Add a 5 seconds of timeouts to connect to S3. The default is 1000ms, but we can hit it a lot of we don't have direct link to AWS (e.g. using VPN).	2019-03-15 13:23:58 +01:00
Graham Christensen	caf297a9d3	Merge pull request #2725 from andir/docs/s3-typo docs: fix typo in AllowDirectReads	2019-03-14 18:53:57 -04:00
Andreas Rammhold	34fade478a	docs: fix typo in AllowDirectReads It was just missing an `l` but should be fixed anyway.	2019-03-14 23:51:18 +01:00
Eelco Dolstra	1f64f4c7c8	pkg-config files: Use c++17	2019-03-14 14:11:12 +01:00
Eelco Dolstra	ef52ccf035	experimental/optional -> optional	2019-03-14 14:10:52 +01:00
Eelco Dolstra	86f3b94c8c	nix-store --gc --print-roots: Sort output	2019-03-14 13:59:10 +01:00
Eelco Dolstra	578ed7a259	findRoots(): Don't censor for trusted users They're pretty much root anyway.	2019-03-14 13:53:34 +01:00
Eelco Dolstra	53522cb6ac	findRoots(): Add 'censor' parameter This is less brittle than filtering paths after the fact in nix-daemon.	2019-03-14 13:53:34 +01:00
Eelco Dolstra	a3f37d87ea	findRuntimeRoots: Simplify/fix handling of /proc files Scanning of /proc/<pid>/{exe,cwd} was broken because '{memory:' was prepended twice. Also, get rid of the whole '{memory:...}' thing because it's unnecessary, we can just list the file in /proc directly.	2019-03-14 13:30:25 +01:00
Guillaume Maudoux	115e2c8c67	Update tests to the new --roots format	2019-03-10 01:50:33 +01:00
Guillaume Maudoux	4f4391193c	Fix warning about unused variable	2019-03-10 00:56:09 +01:00
Guillaume Maudoux	38ee16ae9c	Unify internal findRootsXxx() api	2019-03-10 00:56:09 +01:00
Guillaume Maudoux	9d7221183a	unify naming of roots as links & targets	2019-03-10 00:56:09 +01:00
Guillaume Maudoux	9d87e3fbd2	require c++ 17 This fixes warnings about "structured binding declaration" requiring "-std=c++1z".	2019-03-10 00:56:09 +01:00
Guillaume Maudoux	5c56570726	Also obfuscate the number of memory roots	2019-03-10 00:56:09 +01:00
Guillaume Maudoux	fc02b1b3ee	Also print rooted path in `nix-store -q --roots`	2019-03-10 00:56:09 +01:00
Guillaume Maudoux	8574b70342	fixup! Make roots a map of store paths to pinning links	2019-03-10 00:56:09 +01:00
Guillaume Maudoux	ebc86550f9	Make roots a map of store paths to pinning links This new structure makes more sense as there may be many sources rooting the same store path. Many profiles can reference the same path but this is even more true with /proc/<pid>/maps where distinct pids can and often do map the same store path. This implementation is also more efficient as the `Roots` map contains only one entry per rooted store path.	2019-03-10 00:56:09 +01:00
Guillaume Maudoux	a17f86ce3a	Obfuscate memory roots for non-root users	2019-03-10 00:56:09 +01:00
Guillaume Maudoux	43331d6344	detail memory roots	2019-03-10 00:56:09 +01:00
Eelco Dolstra	5886bc5996	Merge pull request #2710 from volth/patch-6 canBuildLocally: check for features	2019-03-06 13:21:44 +08:00
volth	fff8db205c	canBuildLocally: check for features It could happen that the local builder match the system but lacks some features. Now it results a failure. The fix gracefully excludes the local builder from the set of available builders for derivation which requires the feature, so the derivation is built on remote builders only (as though it has incompatible system, like ```aarch64-linux``` when local is x86)	2019-03-06 05:03:25 +00:00
Eelco Dolstra	b71e1fb342	Restore --init calls in tests	2019-03-04 18:27:45 +08:00
Vladimír Čunát	4cfc131ec4	manual nitpick: document sha512 support in hashString	2019-03-01 14:30:30 +01:00
Will Dietz	0963479741	archive.cc: ignore more posix_fallocate "not supported" error codes Fixes w/musl.	2019-03-01 10:31:17 +08:00
Eelco Dolstra	ad6dbecc1d	Merge pull request #2674 from LnL7/daemon-disable-fork-safety nix-daemon: add variable to disable fork safety	2019-03-01 02:07:50 +01:00
Eelco Dolstra	ebd4d50e6e	Merge pull request #2703 from pradd/support_s3_region_param Support parameters in S3 URLs	2019-02-26 22:59:29 +08:00
Dzmitry Zaitsau	06d6335987	fix indentation	2019-02-26 11:07:37 +01:00
Dzmitry Zaitsau	ac200c3678	Apply param values on S3Helper initialization	2019-02-25 18:06:19 +01:00
Dzmitry Zaitsau	56c18c67d9	Extend S3 URL parsing with parameters extraction	2019-02-25 18:00:55 +01:00
Dzmitry Zaitsau	07f992a74b	Extract and expose splitUriAndParams function which splits a URL into localtor and parameter parts	2019-02-25 17:59:26 +01:00
Austin Seipp	d7a7a029ff	scripts: remove default 'sandbox = false' from multi-user installer Sandboxing is now enabled by default on Linux, but is still disabled on macOS. However, the installer always turned it off to ensure consistent behavior. Remove this default configuration, so we fall back to the default platform-specific value. Signed-off-by: Austin Seipp <aseipp@pobox.com>	2019-02-23 08:35:26 -06:00
Eelco Dolstra	6bfb082ea2	Merge pull request #2694 from zimbatm/no-store-init remove noop uses of nix-store --init	2019-02-23 12:12:36 +01:00
zimbatm	b402148d8f	remove noop uses of nix-store --init the nix-store --init command is a noop apparently	2019-02-22 21:07:53 +01:00
Shea Levy	e58a71442a	nix.sh: Be set -u compliant.	2019-02-14 13:24:16 -05:00
Eelco Dolstra	d8fe447139	Merge pull request #2579 from catern/dumpdb nix-store: make --dump-db take a list of paths to dump	2019-02-14 13:08:02 +01:00
Eelco Dolstra	25722bd39a	Merge pull request #2677 from matthewbauer/disable-shared Support --disable-shared flag.	2019-02-13 10:09:31 +01:00
Matthew Bauer	7ce1fae59f	Support --disable-shared flag. This tells Nix to not build the shared libraries.	2019-02-13 00:03:10 -05:00
Eelco Dolstra	7a7ec22298	Merge pull request #2628 from shlevy/context-introspection Context introspection	2019-02-12 17:57:35 +01:00
Daiderd Jordan	8ac1130cc2	nix-daemon: add variable to disable fork safety Since macOS 10.14 this has become an error, causing problems if the nix-daemon loads nix during substitution (this is a forked process). Workaround for #2523.	2019-02-09 20:35:30 +01:00
Eelco Dolstra	01d07b1e92	Revert "Restore parent mount namespace before executing a child process" This reverts commit `a0ef21262f`. This doesn't work in 'nix run' and nix-shell because setns() fails in multithreaded programs, and Boehm GC mark threads are uncancellable. Fixes #2646.	2019-02-05 10:49:19 +01:00
Shea Levy	b30be6b450	Add builtins.appendContext. A partner of builtins.getContext, useful for the same reasons.	2019-01-31 08:52:23 -05:00
Spencer Baugh	5f1891b795	nix-store: make --dump-db take a list of paths to dump Inside a derivation, exportReferencesGraph already provides a way to dump the Nix database for a specific closure. On the command line, --dump-db gave us the same information, but only for the entire Nix database at once. With this change, one can now pass a list of paths to --dump-db to get the Nix database dumped for just those paths. (The user is responsible for ensuring this is a closure, like for --export). Among other things, this is useful for deploying a closure to a new host without using --import/--export; one can use tar to transfer the store paths, and --dump-db/--load-db to transfer the validity information. This is useful if the new host doesn't actually have Nix yet, and the closure that is being deployed itself contains Nix.	2019-01-23 01:24:34 +00:00
Domen Kožar	92d08c02c8	Merge pull request #2635 from veprbl/patch-7 manual: "sandbox" option default is "true" on Linux	2019-01-20 09:43:26 +07:00
Dmitry Kalinkin	15efd54373	manual: "sandbox" option default is "true" on Linux Fixes: `812e39313c` ('Enable sandboxing by default')	2019-01-19 15:04:43 -05:00
Eelco Dolstra	7cc1a2593e	unsupported(): Show the name of the unsupported operation	2019-01-18 13:34:53 +01:00
Eelco Dolstra	df03430586	Merge pull request #2638 from sevanspowell/update-nix-shell-interpreter-haskell-instructions Update instructions for Haskell script using nix-shell interpreter	2019-01-18 13:17:10 +01:00
Samuel Evans-Powell	2ae5624b2f	Update instructions for Haskell script using nix-shell interpreter - The instructions for using nix-shell as an interpreter has a Haskell script example that doesn't work on more recent versions of Nix. Update the instructions with a working command	2019-01-18 10:50:54 +10:00
Shea Levy	1d757292d0	Add builtins.getContext. This can be very helpful when debugging, as well as enabling complex black magic like surgically removing a single dependency from a string's context.	2019-01-14 11:27:10 -05:00
Shea Levy	087be7281a	Treat plain derivation paths in context as normal paths. Previously, plain derivation paths in the string context (e.g. those that arose from builtins.storePath on a drv file, not those that arose from accessing .drvPath of a derivation) were treated somewhat like derivaiton paths derived from .drvPath, except their dependencies weren't recursively added to the input set. With this change, such plain derivation paths are simply treated as paths and added to the source inputs set accordingly, simplifying context handling code and removing the inconsistency. If drvPath-like behavior is desired, the .drv file can be imported and then .drvPath can be accessed. This is a backwards-incompatibility, but storePath is never used on drv files within nixpkgs and almost never used elsewhere.	2019-01-13 11:29:55 -05:00
Eelco Dolstra	4ae6e84901	install: Use base-16 hashes Issue #2623.	2019-01-11 16:33:59 +01:00
Eelco Dolstra	8ce1986611	Bump version	2019-01-11 16:33:59 +01:00