Merge pull request #7694 from NixOS/backport-7685-to-2.13-maintenance

[Backport 2.13-maintenance] Fix the 2.13 changelog

.github/CODEOWNERS

@@ -0,0 +1,15 @@
+# Pull requests concerning the listed files will automatically invite the respective maintainers as reviewers.
+# This file is not used for denoting any kind of ownership, but is merely a tool for handling notifications.
+#
+# Merge permissions are required for maintaining an entry in this file.
+# For documentation on this mechanism, see https://help.github.com/articles/about-codeowners/
+
+# Default reviewers if nothing else matches
+* @edolstra @thufschmitt
+
+# This file
+.github/CODEOWNERS @edolstra
+
+# Public documentation
+/doc @fricklerhandwerk
+*.md @fricklerhandwerk

.github/ISSUE_TEMPLATE/bug_report.md

@@ -30,3 +30,7 @@ A clear and concise description of what you expected to happen.
 **Additional context**
 
 Add any other context about the problem here.
+
+**Priorities**
+
+Add :+1: to [issues you find important](https://github.com/NixOS/nix/issues?q=is%3Aissue+is%3Aopen+sort%3Areactions-%2B1-desc).

.github/ISSUE_TEMPLATE/feature_request.md

@@ -2,7 +2,7 @@
 name: Feature request
 about: Suggest an idea for this project
 title: ''
-labels: improvement
+labels: feature
 assignees: ''
 
 ---
@@ -18,3 +18,7 @@ A clear and concise description of any alternative solutions or features you've
 
 **Additional context**
 Add any other context or screenshots about the feature request here.
+
+**Priorities**
+
+Add :+1: to [issues you find important](https://github.com/NixOS/nix/issues?q=is%3Aissue+is%3Aopen+sort%3Areactions-%2B1-desc).

.github/ISSUE_TEMPLATE/installer.md

@@ -0,0 +1,36 @@
+---
+name: Installer issue
+about: Report problems with installation
+title: ''
+labels: installer
+assignees: ''
+
+---
+
+## Platform
+
+<!-- select the platform on which you tried to install Nix -->
+
+- [ ] Linux: <!-- state your distribution, e.g. Arch Linux, Ubuntu, ... -->
+- [ ] macOS
+- [ ] WSL
+
+## Additional information
+
+<!-- state special circumstances on your system or additional steps you have taken prior to installation -->
+
+## Output
+
+<details><summary>Output</summary>
+
+```log
+
+<!-- paste console output here and remove this comment -->
+
+```
+
+</details>
+
+## Priorities
+
+Add :+1: to [issues you find important](https://github.com/NixOS/nix/issues?q=is%3Aissue+is%3Aopen+sort%3Areactions-%2B1-desc).

.github/ISSUE_TEMPLATE/missing_documentation.md

@@ -0,0 +1,31 @@
+---
+name: Missing or incorrect documentation
+about: Help us improve the reference manual
+title: ''
+labels: documentation
+assignees: ''
+
+---
+
+## Problem
+
+<!-- describe your problem -->
+
+## Checklist
+
+<!-- make sure this issue is not redundant or obsolete -->
+
+- [ ] checked [latest Nix manual] \([source])
+- [ ] checked [open documentation issues and pull requests] for possible duplicates
+
+[latest Nix manual]: https://nixos.org/manual/nix/unstable/
+[source]: https://github.com/NixOS/nix/tree/master/doc/manual/src
+[open documentation issues and pull requests]: https://github.com/NixOS/nix/labels/documentation
+
+## Proposal
+
+<!-- propose a solution -->
+
+## Priorities
+
+Add :+1: to [issues you find important](https://github.com/NixOS/nix/issues?q=is%3Aissue+is%3Aopen+sort%3Areactions-%2B1-desc).

.github/PULL_REQUEST_TEMPLATE/pull_request_template.md

@@ -5,3 +5,7 @@ Please include relevant [release notes](https://github.com/NixOS/nix/blob/master
 **Testing**
 
 If this issue is a regression or something that should block release, please consider including a test either in the [testsuite](https://github.com/NixOS/nix/tree/master/tests) or as a [hydraJob]( https://github.com/NixOS/nix/blob/master/flake.nix#L396) so that it can be part of the [automatic checks](https://hydra.nixos.org/jobset/nix/master).
+
+**Priorities**
+
+Add :+1: to [pull requests you find important](https://github.com/NixOS/nix/pulls?q=is%3Aopen+sort%3Areactions-%2B1-desc).

.github/stale.yml

@@ -1,10 +1,9 @@
 # Configuration for probot-stale - https://github.com/probot/stale
 daysUntilStale: 180
-daysUntilClose: 365
+daysUntilClose: false
 exemptLabels:
   - "critical"
+  - "never-stale"
 staleLabel: "stale"
-markComment: |
-  I marked this as stale due to inactivity. → [More info](https://github.com/NixOS/nix/blob/master/.github/STALE-BOT.md)
-closeComment: |
-  I closed this issue due to inactivity. → [More info](https://github.com/NixOS/nix/blob/master/.github/STALE-BOT.md)
+markComment: false
+closeComment: false

.github/workflows/backport.yml

@@ -2,9 +2,15 @@ name: Backport
 on:
   pull_request_target:
     types: [closed, labeled]
+permissions:
+  contents: read
 jobs:
   backport:
     name: Backport Pull Request
+    permissions:
+      # for zeebe-io/backport-action
+      contents: write
+      pull-requests: write
     if: github.repository_owner == 'NixOS' && github.event.pull_request.merged == true && (github.event_name != 'labeled' || startsWith('backport', github.event.label.name))
     runs-on: ubuntu-latest
     steps:
@@ -15,7 +21,7 @@ jobs:
           fetch-depth: 0
       - name: Create backport PRs
         # should be kept in sync with `version`
-        uses: zeebe-io/backport-action@v0.0.8
+        uses: zeebe-io/backport-action@v1.0.1
         with:
           # Config README: https://github.com/zeebe-io/backport-action#backport-action
           github_token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/ci.yml

@@ -9,7 +9,7 @@ permissions: read-all
 jobs:
 
   tests:
-    needs: [check_cachix]
+    needs: [check_secrets]
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
@@ -19,33 +19,37 @@ jobs:
     - uses: actions/checkout@v3
       with:
         fetch-depth: 0
-    - uses: cachix/install-nix-action@v17
+    - uses: cachix/install-nix-action@v18
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/cachix-action@v10
-      if: needs.check_cachix.outputs.secret == 'true'
+    - uses: cachix/cachix-action@v12
+      if: needs.check_secrets.outputs.cachix == 'true'
       with:
         name: '${{ env.CACHIX_NAME }}'
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
         authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
     - run: nix --experimental-features 'nix-command flakes' flake check -L
 
-  check_cachix:
+  check_secrets:
     permissions:
       contents: none
-    name: Cachix secret present for installer tests
+    name: Check Cachix and Docker secrets present for installer tests
     runs-on: ubuntu-latest
     outputs:
-      secret: ${{ steps.secret.outputs.secret }}
+      cachix: ${{ steps.secret.outputs.cachix }}
+      docker: ${{ steps.secret.outputs.docker }}
     steps:
-      - name: Check for Cachix secret
+      - name: Check for secrets
         id: secret
         env:
           _CACHIX_SECRETS: ${{ secrets.CACHIX_SIGNING_KEY }}${{ secrets.CACHIX_AUTH_TOKEN }}
-        run: echo "::set-output name=secret::${{ env._CACHIX_SECRETS != '' }}"
+          _DOCKER_SECRETS: ${{ secrets.DOCKERHUB_USERNAME }}${{ secrets.DOCKERHUB_TOKEN }}
+        run: |
+          echo "::set-output name=cachix::${{ env._CACHIX_SECRETS != '' }}"
+          echo "::set-output name=docker::${{ env._DOCKER_SECRETS != '' }}"
 
   installer:
-    needs: [tests, check_cachix]
-    if: github.event_name == 'push' && needs.check_cachix.outputs.secret == 'true'
+    needs: [tests, check_secrets]
+    if: github.event_name == 'push' && needs.check_secrets.outputs.cachix == 'true'
     runs-on: ubuntu-latest
     outputs:
       installerURL: ${{ steps.prepare-installer.outputs.installerURL }}
@@ -54,8 +58,8 @@ jobs:
       with:
         fetch-depth: 0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v17
-    - uses: cachix/cachix-action@v10
+    - uses: cachix/install-nix-action@v18
+    - uses: cachix/cachix-action@v12
       with:
         name: '${{ env.CACHIX_NAME }}'
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
@@ -64,8 +68,8 @@ jobs:
       run: scripts/prepare-installer-for-github-actions
 
   installer_test:
-    needs: [installer, check_cachix]
-    if: github.event_name == 'push' && needs.check_cachix.outputs.secret == 'true'
+    needs: [installer, check_secrets]
+    if: github.event_name == 'push' && needs.check_secrets.outputs.cachix == 'true'
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest]
@@ -73,28 +77,36 @@ jobs:
     steps:
     - uses: actions/checkout@v3
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v17
+    - uses: cachix/install-nix-action@v18
       with:
         install_url: '${{needs.installer.outputs.installerURL}}'
         install_options: "--tarball-url-prefix https://${{ env.CACHIX_NAME }}.cachix.org/serve"
-    - run: nix-instantiate -E 'builtins.currentTime' --eval
+    - run: sudo apt install fish zsh
+      if: matrix.os == 'ubuntu-latest'
+    - run: brew install fish
+      if: matrix.os == 'macos-latest'
+    - run: exec bash -c "nix-instantiate -E 'builtins.currentTime' --eval"
+    - run: exec sh -c "nix-instantiate -E 'builtins.currentTime' --eval"
+    - run: exec zsh -c "nix-instantiate -E 'builtins.currentTime' --eval"
+    - run: exec fish -c "nix-instantiate -E 'builtins.currentTime' --eval"
 
   docker_push_image:
-    needs: [check_cachix, tests]
+    needs: [check_secrets, tests]
     if: >-
       github.event_name == 'push' &&
       github.ref_name == 'master' &&
-      needs.check_cachix.outputs.secret == 'true'
+      needs.check_secrets.outputs.cachix == 'true' &&
+      needs.check_secrets.outputs.docker == 'true'
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
       with:
         fetch-depth: 0
-    - uses: cachix/install-nix-action@v17
+    - uses: cachix/install-nix-action@v18
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
     - run: echo NIX_VERSION="$(nix --experimental-features 'nix-command flakes' eval .\#default.version | tr -d \")" >> $GITHUB_ENV
-    - uses: cachix/cachix-action@v10
-      if: needs.check_cachix.outputs.secret == 'true'
+    - uses: cachix/cachix-action@v12
+      if: needs.check_secrets.outputs.cachix == 'true'
       with:
         name: '${{ env.CACHIX_NAME }}'
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'

.gitignore

@@ -22,11 +22,13 @@ perl/Makefile.config
 /doc/manual/src/SUMMARY.md
 /doc/manual/src/command-ref/new-cli
 /doc/manual/src/command-ref/conf-file.md
-/doc/manual/src/expressions/builtins.md
+/doc/manual/src/language/builtins.md
 
 # /scripts/
 /scripts/nix-profile.sh
 /scripts/nix-profile-daemon.sh
+/scripts/nix-profile.fish
+/scripts/nix-profile-daemon.fish
 
 # /src/libexpr/
 /src/libexpr/lexer-tab.cc

.version

@@ -1 +1 @@
-2.10.0
+2.13.2

README.md

@@ -20,7 +20,7 @@ Information on additional installation methods is available on the [Nix download
 
 ## Building And Developing
 
-See our [Hacking guide](https://hydra.nixos.org/job/nix/master/build.x86_64-linux/latest/download-by-type/doc/manual/contributing/hacking.html) in our manual for instruction on how to
+See our [Hacking guide](https://nixos.org/manual/nix/stable/contributing/hacking.html) in our manual for instruction on how to
 build nix from source with nix-build or how to get a development environment.
 
 ## Additional Resources

boehmgc-coroutine-sp-fallback.diff

@@ -1,17 +1,49 @@
+diff --git a/darwin_stop_world.c b/darwin_stop_world.c
+index 3dbaa3fb..36a1d1f7 100644
+--- a/darwin_stop_world.c
++++ b/darwin_stop_world.c
+@@ -352,6 +352,7 @@ GC_INNER void GC_push_all_stacks(void)
+   int nthreads = 0;
+   word total_size = 0;
+   mach_msg_type_number_t listcount = (mach_msg_type_number_t)THREAD_TABLE_SZ;
++  size_t stack_limit;
+   if (!EXPECT(GC_thr_initialized, TRUE))
+     GC_thr_init();
+ 
+@@ -407,6 +408,19 @@ GC_INNER void GC_push_all_stacks(void)
+             GC_push_all_stack_sections(lo, hi, p->traced_stack_sect);
+           }
+           if (altstack_lo) {
++            // When a thread goes into a coroutine, we lose its original sp until
++            // control flow returns to the thread.
++            // While in the coroutine, the sp points outside the thread stack,
++            // so we can detect this and push the entire thread stack instead,
++            // as an approximation.
++            // We assume that the coroutine has similarly added its entire stack.
++            // This could be made accurate by cooperating with the application
++            // via new functions and/or callbacks.
++            stack_limit = pthread_get_stacksize_np(p->id);
++            if (altstack_lo >= altstack_hi || altstack_lo < altstack_hi - stack_limit) { // sp outside stack
++              altstack_lo = altstack_hi - stack_limit;
++            }
++
+             total_size += altstack_hi - altstack_lo;
+             GC_push_all_stack(altstack_lo, altstack_hi);
+           }
 diff --git a/pthread_stop_world.c b/pthread_stop_world.c
-index 4b2c429..1fb4c52 100644
+index b5d71e62..aed7b0bf 100644
 --- a/pthread_stop_world.c
 +++ b/pthread_stop_world.c
-@@ -673,6 +673,8 @@ GC_INNER void GC_push_all_stacks(void)
-     struct GC_traced_stack_sect_s *traced_stack_sect;
-     pthread_t self = pthread_self();
-     word total_size = 0;
+@@ -768,6 +768,8 @@ STATIC void GC_restart_handler(int sig)
+ /* world is stopped.  Should not fail if it isn't.                      */
+ GC_INNER void GC_push_all_stacks(void)
+ {
 +    size_t stack_limit;
 +    pthread_attr_t pattr;
- 
-     if (!EXPECT(GC_thr_initialized, TRUE))
-       GC_thr_init();
-@@ -722,6 +724,31 @@ GC_INNER void GC_push_all_stacks(void)
+     GC_bool found_me = FALSE;
+     size_t nthreads = 0;
+     int i;
+@@ -851,6 +853,31 @@ GC_INNER void GC_push_all_stacks(void)
            hi = p->altstack + p->altstack_size;
            /* FIXME: Need to scan the normal stack too, but how ? */
            /* FIXME: Assume stack grows down */

configure.ac

@@ -41,8 +41,6 @@ AC_DEFINE_UNQUOTED(SYSTEM, ["$system"], [platform identifier ('cpu-os')])
 test "$localstatedir" = '${prefix}/var' && localstatedir=/nix/var
 
 
-CFLAGS=
-CXXFLAGS=
 AC_PROG_CC
 AC_PROG_CXX
 AC_PROG_CPP
@@ -177,7 +175,7 @@ fi
 PKG_CHECK_MODULES([OPENSSL], [libcrypto], [CXXFLAGS="$OPENSSL_CFLAGS $CXXFLAGS"])
 
 
-# Checks for libarchive
+# Look for libarchive.
 PKG_CHECK_MODULES([LIBARCHIVE], [libarchive >= 3.1.2], [CXXFLAGS="$LIBARCHIVE_CFLAGS $CXXFLAGS"])
 # Workaround until https://github.com/libarchive/libarchive/issues/1446 is fixed
 if test "$shared" != yes; then
@@ -296,15 +294,6 @@ AC_CHECK_FUNCS([setresuid setreuid lchown])
 AC_CHECK_FUNCS([strsignal posix_fallocate sysconf])
 
 
-# This is needed if bzip2 is a static library, and the Nix libraries
-# are dynamic.
-case "${host_os}" in
-  darwin*)
-    LDFLAGS="-all_load $LDFLAGS"
-    ;;
-esac
-
-
 AC_ARG_WITH(sandbox-shell, AS_HELP_STRING([--with-sandbox-shell=PATH],[path of a statically-linked shell to use as /bin/sh in sandboxes]),
   sandbox_shell=$withval)
 AC_SUBST(sandbox_shell)

doc/manual/book.toml

@@ -1,7 +1,21 @@
+[book]
+title = "Nix Reference Manual"
+
 [output.html]
 additional-css = ["custom.css"]
 additional-js = ["redirects.js"]
+edit-url-template = "https://github.com/NixOS/nix/tree/master/doc/manual/{path}"
+git-repository-url = "https://github.com/NixOS/nix"
 
 [preprocessor.anchors]
 renderers = ["html"]
 command = "jq --from-file doc/manual/anchors.jq"
+
+[output.linkcheck]
+# no Internet during the build (in the sandbox)
+follow-web-links = false
+
+# mdbook-linkcheck does not understand [foo]{#bar} style links, resulting in
+# excessive "Potential incomplete link" warnings. No other kind of warning was
+# produced at the time of writing.
+warning-policy = "ignore"

doc/manual/generate-builtins.nix

@@ -1,16 +1,20 @@
-with builtins;
-with import ./utils.nix;
+builtinsDump:
+let
+  showBuiltin = name:
+    let
+      inherit (builtinsDump.${name}) doc args;
+    in
+    ''
+      <dt id="builtins-${name}">
+        <a href="#builtins-${name}"><code>${name} ${listArgs args}</code></a>
+      </dt>
+      <dd>
 
-builtins:
+        ${doc}
+
+      </dd>
+    '';
+  listArgs = args: builtins.concatStringsSep " " (map (s: "<var>${s}</var>") args);
+in
+with builtins; concatStringsSep "\n" (map showBuiltin (attrNames builtinsDump))
 
-concatStrings (map
-  (name:
-    let builtin = builtins.${name}; in
-    "<dt id=\"builtins-${name}\"><a href=\"#builtins-${name}\"><code>${name} "
-    + concatStringsSep " " (map (s: "<var>${s}</var>") builtin.args)
-    + "</code></a></dt>"
-    + "<dd>\n\n"
-    + builtin.doc
-    + "\n\n</dd>"
-  )
-  (attrNames builtins))

doc/manual/generate-manpage.nix

@@ -1,99 +1,115 @@
-{ command, renderLinks ? false }:
+{ toplevel }:
 
 with builtins;
 with import ./utils.nix;
 
 let
 
-  showCommand =
-    { command, def, filename }:
-    ''
-      **Warning**: This program is **experimental** and its interface is subject to change.
-    ''
-    + "# Name\n\n"
-    + "`${command}` - ${def.description}\n\n"
-    + "# Synopsis\n\n"
-    + showSynopsis { inherit command; args = def.args; }
-    + (if def.commands or {} != {}
-       then
-         let
-           categories = sort (x: y: x.id < y.id) (unique (map (cmd: cmd.category) (attrValues def.commands)));
-           listCommands = cmds:
-             concatStrings (map (name:
-               "* "
-               + (if renderLinks
-                  then "[`${command} ${name}`](./${appendName filename name}.md)"
-                  else "`${command} ${name}`")
-               + " - ${cmds.${name}.description}\n")
-               (attrNames cmds));
-         in
-         "where *subcommand* is one of the following:\n\n"
-         # FIXME: group by category
-         + (if length categories > 1
-            then
-              concatStrings (map
-                (cat:
-                  "**${toString cat.description}:**\n\n"
-                  + listCommands (filterAttrs (n: v: v.category == cat) def.commands)
-                  + "\n"
-                ) categories)
-              + "\n"
-            else
-              listCommands def.commands
-              + "\n")
-       else "")
-    + (if def ? doc
-       then def.doc + "\n\n"
-       else "")
-    + (let s = showOptions def.flags; in
-       if s != ""
-       then "# Options\n\n${s}"
-       else "")
-  ;
+  showCommand = { command, details, filename, toplevel }:
+    let
+      result = ''
+        > **Warning** \
+        > This program is **experimental** and its interface is subject to change.
+
+        # Name
+
+        `${command}` - ${details.description}
+
+        # Synopsis
+
+        ${showSynopsis command details.args}
+
+        ${maybeSubcommands}
+
+        ${maybeDocumentation}
+
+        ${maybeOptions}
+      '';
+      showSynopsis = command: args:
+        let
+          showArgument = arg: "*${arg.label}*" + (if arg ? arity then "" else "...");
+          arguments = concatStringsSep " " (map showArgument args);
+        in ''
+         `${command}` [*option*...] ${arguments}
+        '';
+      maybeSubcommands = if details ? commands && details.commands != {}
+        then ''
+           where *subcommand* is one of the following:
+
+           ${subcommands}
+         ''
+        else "";
+      subcommands = if length categories > 1
+        then listCategories
+        else listSubcommands details.commands;
+      categories = sort (x: y: x.id < y.id) (unique (map (cmd: cmd.category) (attrValues details.commands)));
+      listCategories = concatStrings (map showCategory categories);
+      showCategory = cat: ''
+        **${toString cat.description}:**
+
+        ${listSubcommands (filterAttrs (n: v: v.category == cat) details.commands)}
+      '';
+      listSubcommands = cmds: concatStrings (attrValues (mapAttrs showSubcommand cmds));
+      showSubcommand = name: subcmd: ''
+        * [`${command} ${name}`](./${appendName filename name}.md) - ${subcmd.description}
+      '';
+      maybeDocumentation = if details ? doc then details.doc else "";
+      maybeOptions = if details.flags == {} then "" else ''
+        # Options
+
+        ${showOptions details.flags toplevel.flags}
+      '';
+      showOptions = options: commonOptions:
+        let
+          allOptions = options // commonOptions;
+          showCategory = cat: ''
+            ${if cat != "" then "**${cat}:**" else ""}
+
+            ${listOptions (filterAttrs (n: v: v.category == cat) allOptions)}
+            '';
+          listOptions = opts: concatStringsSep "\n" (attrValues (mapAttrs showOption opts));
+          showOption = name: option:
+            let
+              shortName = if option ? shortName then "/ `-${option.shortName}`" else "";
+              labels = if option ? labels then (concatStringsSep " " (map (s: "*${s}*") option.labels)) else "";
+            in trim ''
+              - `--${name}` ${shortName} ${labels}
+
+                ${option.description}
+            '';
+          categories = sort builtins.lessThan (unique (map (cmd: cmd.category) (attrValues allOptions)));
+        in concatStrings (map showCategory categories);
+    in squash result;
 
   appendName = filename: name: (if filename == "nix" then "nix3" else filename) + "-" + name;
 
-  showOptions = flags:
+  processCommand = { command, details, filename, toplevel }:
     let
-      categories = sort builtins.lessThan (unique (map (cmd: cmd.category) (attrValues flags)));
-    in
-      concatStrings (map
-        (cat:
-          (if cat != ""
-           then "**${cat}:**\n\n"
-           else "")
-          + concatStrings
-            (map (longName:
-              let
-                flag = flags.${longName};
-              in
-                "  - `--${longName}`"
-                + (if flag ? shortName then " / `-${flag.shortName}`" else "")
-                + (if flag ? labels then " " + (concatStringsSep " " (map (s: "*${s}*") flag.labels)) else "")
-                + "  \n"
-                + "    " + flag.description + "\n\n"
-            ) (attrNames (filterAttrs (n: v: v.category == cat) flags))))
-        categories);
+      cmd = {
+        inherit command;
+        name = filename + ".md";
+        value = showCommand { inherit command details filename toplevel; };
+      };
+      subcommand = subCmd: processCommand {
+        command = command + " " + subCmd;
+        details = details.commands.${subCmd};
+        filename = appendName filename subCmd;
+        inherit toplevel;
+      };
+    in [ cmd ] ++ concatMap subcommand (attrNames details.commands or {});
 
-  showSynopsis =
-    { command, args }:
-    "`${command}` [*option*...] ${concatStringsSep " "
-      (map (arg: "*${arg.label}*" + (if arg ? arity then "" else "...")) args)}\n\n";
+  parsedToplevel = builtins.fromJSON toplevel;
+  
+  manpages = processCommand {
+    command = "nix";
+    details = parsedToplevel;
+    filename = "nix";
+    toplevel = parsedToplevel;
+  };
 
-  processCommand = { command, def, filename }:
-    [ { name = filename + ".md"; value = showCommand { inherit command def filename; }; inherit command; } ]
-    ++ concatMap
-      (name: processCommand {
-        filename = appendName filename name;
-        command = command + " " + name;
-        def = def.commands.${name};
-      })
-      (attrNames def.commands or {});
+  tableOfContents = let
+    showEntry = page:
+      "    - [${page.command}](command-ref/new-cli/${page.name})";
+    in concatStringsSep "\n" (map showEntry manpages) + "\n";
 
-in
-
-let
-  manpages = processCommand { filename = "nix"; command = "nix"; def = builtins.fromJSON command; };
-  summary = concatStrings (map (manpage: "    - [${manpage.command}](command-ref/new-cli/${manpage.name})\n") manpages);
-in
-(listToAttrs manpages) // { "SUMMARY.md" = summary; }
+in (listToAttrs manpages) // { "SUMMARY.md" = tableOfContents; }

doc/manual/generate-options.nix

@@ -1,29 +1,41 @@
-with builtins;
-with import ./utils.nix;
+let
+  inherit (builtins) attrNames concatStringsSep isAttrs isBool;
+  inherit (import ./utils.nix) concatStrings squash splitLines;
+in
 
-options:
+optionsInfo:
+let
+  showOption = name:
+    let
+      inherit (optionsInfo.${name}) description documentDefault defaultValue aliases;
+      result = squash ''
+          - <span id="conf-${name}">[`${name}`](#conf-${name})</span>
 
-concatStrings (map
-  (name:
-    let option = options.${name}; in
-    "  - [`${name}`](#conf-${name})"
-    + "<p id=\"conf-${name}\"></p>\n\n"
-    + concatStrings (map (s: "    ${s}\n") (splitLines option.description)) + "\n\n"
-    + (if option.documentDefault
-       then "    **Default:** " + (
-       if option.value == "" || option.value == []
-       then "*empty*"
-       else if isBool option.value
-       then (if option.value then "`true`" else "`false`")
-       else
-         # n.b. a StringMap value type is specified as a string, but
-         # this shows the value type.  The empty stringmap is "null" in
-         # JSON, but that converts to "{ }" here.
-         (if isAttrs option.value then "`\"\"`"
-          else "`" + toString option.value + "`")) + "\n\n"
-       else "    **Default:** *machine-specific*\n")
-    + (if option.aliases != []
-       then "    **Deprecated alias:** " + (concatStringsSep ", " (map (s: "`${s}`") option.aliases)) + "\n\n"
-       else "")
-    )
-  (attrNames options))
+          ${indent "  " body}
+        '';
+      # separate body to cleanly handle indentation
+      body = ''
+          ${description}
+
+          **Default:** ${showDefault documentDefault defaultValue}
+
+          ${showAliases aliases}
+        '';
+      showDefault = documentDefault: defaultValue:
+        if documentDefault then
+          # a StringMap value type is specified as a string, but
+          # this shows the value type. The empty stringmap is `null` in
+          # JSON, but that converts to `{ }` here.
+          if defaultValue == "" || defaultValue == [] || isAttrs defaultValue
+            then "*empty*"
+            else if isBool defaultValue then
+              if defaultValue then "`true`" else "`false`"
+            else "`${toString defaultValue}`"
+        else "*machine-specific*";
+      showAliases = aliases:
+          if aliases == [] then "" else
+            "**Deprecated alias:** ${(concatStringsSep ", " (map (s: "`${s}`") aliases))}";
+      indent = prefix: s:
+        concatStringsSep "\n" (map (x: if x == "" then x else "${prefix}${x}") (splitLines s));
+      in result;
+in concatStrings (map showOption (attrNames optionsInfo))

doc/manual/local.mk

@@ -1,5 +1,9 @@
 ifeq ($(doc_generate),yes)
 
+MANUAL_SRCS := \
+  $(call rwildcard, $(d)/src, *.md) \
+  $(call rwildcard, $(d)/src, */*.md)
+
 # Generate man pages.
 man-pages := $(foreach n, \
   nix-env.1 nix-build.1 nix-shell.1 nix-store.1 nix-instantiate.1 \
@@ -25,19 +29,19 @@ nix-eval = $(dummy-env) $(bindir)/nix eval --experimental-features nix-command -
 $(d)/%.1: $(d)/src/command-ref/%.md
 	@printf "Title: %s\n\n" "$$(basename $@ .1)" > $^.tmp
 	@cat $^ >> $^.tmp
-	$(trace-gen) lowdown -sT man -M section=1 $^.tmp -o $@
+	$(trace-gen) lowdown -sT man --nroff-nolinks -M section=1 $^.tmp -o $@
 	@rm $^.tmp
 
 $(d)/%.8: $(d)/src/command-ref/%.md
 	@printf "Title: %s\n\n" "$$(basename $@ .8)" > $^.tmp
 	@cat $^ >> $^.tmp
-	$(trace-gen) lowdown -sT man -M section=8 $^.tmp -o $@
+	$(trace-gen) lowdown -sT man --nroff-nolinks -M section=8 $^.tmp -o $@
 	@rm $^.tmp
 
 $(d)/nix.conf.5: $(d)/src/command-ref/conf-file.md
 	@printf "Title: %s\n\n" "$$(basename $@ .5)" > $^.tmp
 	@cat $^ >> $^.tmp
-	$(trace-gen) lowdown -sT man -M section=5 $^.tmp -o $@
+	$(trace-gen) lowdown -sT man --nroff-nolinks -M section=5 $^.tmp -o $@
 	@rm $^.tmp
 
 $(d)/src/SUMMARY.md: $(d)/src/SUMMARY.md.in $(d)/src/command-ref/new-cli
@@ -46,11 +50,16 @@ $(d)/src/SUMMARY.md: $(d)/src/SUMMARY.md.in $(d)/src/command-ref/new-cli
 
 $(d)/src/command-ref/new-cli: $(d)/nix.json $(d)/generate-manpage.nix $(bindir)/nix
 	@rm -rf $@
-	$(trace-gen) $(nix-eval) --write-to $@ --expr 'import doc/manual/generate-manpage.nix { command = builtins.readFile $<; renderLinks = true; }'
+	$(trace-gen) $(nix-eval) --write-to $@.tmp --expr 'import doc/manual/generate-manpage.nix { toplevel = builtins.readFile $<; }'
+	# @docroot@: https://nixos.org/manual/nix/unstable/contributing/hacking.html#docroot-variable
+	$(trace-gen) sed -i $@.tmp/*.md -e 's^@docroot@^../..^g'
+	@mv $@.tmp $@
 
 $(d)/src/command-ref/conf-file.md: $(d)/conf-file.json $(d)/generate-options.nix $(d)/src/command-ref/conf-file-prefix.md $(bindir)/nix
 	@cat doc/manual/src/command-ref/conf-file-prefix.md > $@.tmp
-	$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-options.nix (builtins.fromJSON (builtins.readFile $<))' >> $@.tmp
+	# @docroot@: https://nixos.org/manual/nix/unstable/contributing/hacking.html#docroot-variable
+	$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-options.nix (builtins.fromJSON (builtins.readFile $<))' \
+	  | sed -e 's^@docroot@^..^g'>> $@.tmp
 	@mv $@.tmp $@
 
 $(d)/nix.json: $(bindir)/nix
@@ -61,10 +70,12 @@ $(d)/conf-file.json: $(bindir)/nix
 	$(trace-gen) $(dummy-env) $(bindir)/nix show-config --json --experimental-features nix-command > $@.tmp
 	@mv $@.tmp $@
 
-$(d)/src/expressions/builtins.md: $(d)/builtins.json $(d)/generate-builtins.nix $(d)/src/expressions/builtins-prefix.md $(bindir)/nix
-	@cat doc/manual/src/expressions/builtins-prefix.md > $@.tmp
-	$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-builtins.nix (builtins.fromJSON (builtins.readFile $<))' >> $@.tmp
-	@cat doc/manual/src/expressions/builtins-suffix.md >> $@.tmp
+$(d)/src/language/builtins.md: $(d)/builtins.json $(d)/generate-builtins.nix $(d)/src/language/builtins-prefix.md $(bindir)/nix
+	@cat doc/manual/src/language/builtins-prefix.md > $@.tmp
+	# @docroot@: https://nixos.org/manual/nix/unstable/contributing/hacking.html#docroot-variable
+	$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-builtins.nix (builtins.fromJSON (builtins.readFile $<))' \
+	  | sed -e 's^@docroot@^..^g' >> $@.tmp
+	@cat doc/manual/src/language/builtins-suffix.md >> $@.tmp
 	@mv $@.tmp $@
 
 $(d)/builtins.json: $(bindir)/nix
@@ -92,12 +103,18 @@ doc/manual/generated/man1/nix3-manpages: $(d)/src/command-ref/new-cli
 	  if [[ $$name = SUMMARY ]]; then continue; fi; \
 	  printf "Title: %s\n\n" "$$name" > $$tmpFile; \
 	  cat $$i >> $$tmpFile; \
-	  lowdown -sT man -M section=1 $$tmpFile -o $(DESTDIR)$$(dirname $@)/$$name.1; \
+	  lowdown -sT man --nroff-nolinks -M section=1 $$tmpFile -o $(DESTDIR)$$(dirname $@)/$$name.1; \
 	  rm $$tmpFile; \
 	done
 	@touch $@
 
-$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/anchors.jq $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/command-ref/new-cli $(d)/src/command-ref/conf-file.md $(d)/src/expressions/builtins.md $(call rwildcard, $(d)/src, *.md)
-	$(trace-gen) RUST_LOG=warn mdbook build doc/manual -d $(DESTDIR)$(docdir)/manual
+$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/anchors.jq $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/command-ref/new-cli $(d)/src/command-ref/conf-file.md $(d)/src/language/builtins.md
+	$(trace-gen) \
+	  set -euo pipefail; \
+	  RUST_LOG=warn mdbook build doc/manual -d $(DESTDIR)$(docdir)/manual.tmp 2>&1 \
+		  | { grep -Fv "because fragment resolution isn't implemented" || :; }
+	@rm -rf $(DESTDIR)$(docdir)/manual
+	@mv $(DESTDIR)$(docdir)/manual.tmp/html $(DESTDIR)$(docdir)/manual
+	@rm -rf $(DESTDIR)$(docdir)/manual.tmp
 
 endif

doc/manual/redirects.js

@@ -1,337 +1,421 @@
-// Redirects from old DocBook manual.
-var redirects = {
-  "#part-advanced-topics": "advanced-topics/advanced-topics.html",
-  "#chap-tuning-cores-and-jobs": "advanced-topics/cores-vs-jobs.html",
-  "#chap-diff-hook": "advanced-topics/diff-hook.html",
-  "#check-dirs-are-unregistered": "advanced-topics/diff-hook.html#check-dirs-are-unregistered",
-  "#chap-distributed-builds": "advanced-topics/distributed-builds.html",
-  "#chap-post-build-hook": "advanced-topics/post-build-hook.html",
-  "#chap-post-build-hook-caveats": "advanced-topics/post-build-hook.html#implementation-caveats",
-  "#part-command-ref": "command-ref/command-ref.html",
-  "#conf-allow-import-from-derivation": "command-ref/conf-file.html#conf-allow-import-from-derivation",
-  "#conf-allow-new-privileges": "command-ref/conf-file.html#conf-allow-new-privileges",
-  "#conf-allowed-uris": "command-ref/conf-file.html#conf-allowed-uris",
-  "#conf-allowed-users": "command-ref/conf-file.html#conf-allowed-users",
-  "#conf-auto-optimise-store": "command-ref/conf-file.html#conf-auto-optimise-store",
-  "#conf-binary-cache-public-keys": "command-ref/conf-file.html#conf-binary-cache-public-keys",
-  "#conf-binary-caches": "command-ref/conf-file.html#conf-binary-caches",
-  "#conf-build-compress-log": "command-ref/conf-file.html#conf-build-compress-log",
-  "#conf-build-cores": "command-ref/conf-file.html#conf-build-cores",
-  "#conf-build-extra-chroot-dirs": "command-ref/conf-file.html#conf-build-extra-chroot-dirs",
-  "#conf-build-extra-sandbox-paths": "command-ref/conf-file.html#conf-build-extra-sandbox-paths",
-  "#conf-build-fallback": "command-ref/conf-file.html#conf-build-fallback",
-  "#conf-build-max-jobs": "command-ref/conf-file.html#conf-build-max-jobs",
-  "#conf-build-max-log-size": "command-ref/conf-file.html#conf-build-max-log-size",
-  "#conf-build-max-silent-time": "command-ref/conf-file.html#conf-build-max-silent-time",
-  "#conf-build-repeat": "command-ref/conf-file.html#conf-build-repeat",
-  "#conf-build-timeout": "command-ref/conf-file.html#conf-build-timeout",
-  "#conf-build-use-chroot": "command-ref/conf-file.html#conf-build-use-chroot",
-  "#conf-build-use-sandbox": "command-ref/conf-file.html#conf-build-use-sandbox",
-  "#conf-build-use-substitutes": "command-ref/conf-file.html#conf-build-use-substitutes",
-  "#conf-build-users-group": "command-ref/conf-file.html#conf-build-users-group",
-  "#conf-builders": "command-ref/conf-file.html#conf-builders",
-  "#conf-builders-use-substitutes": "command-ref/conf-file.html#conf-builders-use-substitutes",
-  "#conf-compress-build-log": "command-ref/conf-file.html#conf-compress-build-log",
-  "#conf-connect-timeout": "command-ref/conf-file.html#conf-connect-timeout",
-  "#conf-cores": "command-ref/conf-file.html#conf-cores",
-  "#conf-diff-hook": "command-ref/conf-file.html#conf-diff-hook",
-  "#conf-enforce-determinism": "command-ref/conf-file.html#conf-enforce-determinism",
-  "#conf-env-keep-derivations": "command-ref/conf-file.html#conf-env-keep-derivations",
-  "#conf-extra-binary-caches": "command-ref/conf-file.html#conf-extra-binary-caches",
-  "#conf-extra-platforms": "command-ref/conf-file.html#conf-extra-platforms",
-  "#conf-extra-sandbox-paths": "command-ref/conf-file.html#conf-extra-sandbox-paths",
-  "#conf-extra-substituters": "command-ref/conf-file.html#conf-extra-substituters",
-  "#conf-fallback": "command-ref/conf-file.html#conf-fallback",
-  "#conf-fsync-metadata": "command-ref/conf-file.html#conf-fsync-metadata",
-  "#conf-gc-keep-derivations": "command-ref/conf-file.html#conf-gc-keep-derivations",
-  "#conf-gc-keep-outputs": "command-ref/conf-file.html#conf-gc-keep-outputs",
-  "#conf-hashed-mirrors": "command-ref/conf-file.html#conf-hashed-mirrors",
-  "#conf-http-connections": "command-ref/conf-file.html#conf-http-connections",
-  "#conf-keep-build-log": "command-ref/conf-file.html#conf-keep-build-log",
-  "#conf-keep-derivations": "command-ref/conf-file.html#conf-keep-derivations",
-  "#conf-keep-env-derivations": "command-ref/conf-file.html#conf-keep-env-derivations",
-  "#conf-keep-outputs": "command-ref/conf-file.html#conf-keep-outputs",
-  "#conf-max-build-log-size": "command-ref/conf-file.html#conf-max-build-log-size",
-  "#conf-max-free": "command-ref/conf-file.html#conf-max-free",
-  "#conf-max-jobs": "command-ref/conf-file.html#conf-max-jobs",
-  "#conf-max-silent-time": "command-ref/conf-file.html#conf-max-silent-time",
-  "#conf-min-free": "command-ref/conf-file.html#conf-min-free",
-  "#conf-narinfo-cache-negative-ttl": "command-ref/conf-file.html#conf-narinfo-cache-negative-ttl",
-  "#conf-narinfo-cache-positive-ttl": "command-ref/conf-file.html#conf-narinfo-cache-positive-ttl",
-  "#conf-netrc-file": "command-ref/conf-file.html#conf-netrc-file",
-  "#conf-plugin-files": "command-ref/conf-file.html#conf-plugin-files",
-  "#conf-post-build-hook": "command-ref/conf-file.html#conf-post-build-hook",
-  "#conf-pre-build-hook": "command-ref/conf-file.html#conf-pre-build-hook",
-  "#conf-repeat": "command-ref/conf-file.html#conf-repeat",
-  "#conf-require-sigs": "command-ref/conf-file.html#conf-require-sigs",
-  "#conf-restrict-eval": "command-ref/conf-file.html#conf-restrict-eval",
-  "#conf-run-diff-hook": "command-ref/conf-file.html#conf-run-diff-hook",
-  "#conf-sandbox": "command-ref/conf-file.html#conf-sandbox",
-  "#conf-sandbox-dev-shm-size": "command-ref/conf-file.html#conf-sandbox-dev-shm-size",
-  "#conf-sandbox-paths": "command-ref/conf-file.html#conf-sandbox-paths",
-  "#conf-secret-key-files": "command-ref/conf-file.html#conf-secret-key-files",
-  "#conf-show-trace": "command-ref/conf-file.html#conf-show-trace",
-  "#conf-stalled-download-timeout": "command-ref/conf-file.html#conf-stalled-download-timeout",
-  "#conf-substitute": "command-ref/conf-file.html#conf-substitute",
-  "#conf-substituters": "command-ref/conf-file.html#conf-substituters",
-  "#conf-system": "command-ref/conf-file.html#conf-system",
-  "#conf-system-features": "command-ref/conf-file.html#conf-system-features",
-  "#conf-tarball-ttl": "command-ref/conf-file.html#conf-tarball-ttl",
-  "#conf-timeout": "command-ref/conf-file.html#conf-timeout",
-  "#conf-trace-function-calls": "command-ref/conf-file.html#conf-trace-function-calls",
-  "#conf-trusted-binary-caches": "command-ref/conf-file.html#conf-trusted-binary-caches",
-  "#conf-trusted-public-keys": "command-ref/conf-file.html#conf-trusted-public-keys",
-  "#conf-trusted-substituters": "command-ref/conf-file.html#conf-trusted-substituters",
-  "#conf-trusted-users": "command-ref/conf-file.html#conf-trusted-users",
-  "#extra-sandbox-paths": "command-ref/conf-file.html#extra-sandbox-paths",
-  "#sec-conf-file": "command-ref/conf-file.html",
-  "#env-NIX_PATH": "command-ref/env-common.html#env-NIX_PATH",
-  "#env-common": "command-ref/env-common.html",
-  "#envar-remote": "command-ref/env-common.html#env-NIX_REMOTE",
-  "#sec-common-env": "command-ref/env-common.html",
-  "#ch-files": "command-ref/files.html",
-  "#ch-main-commands": "command-ref/main-commands.html",
-  "#opt-out-link": "command-ref/nix-build.html#opt-out-link",
-  "#sec-nix-build": "command-ref/nix-build.html",
-  "#sec-nix-channel": "command-ref/nix-channel.html",
-  "#sec-nix-collect-garbage": "command-ref/nix-collect-garbage.html",
-  "#sec-nix-copy-closure": "command-ref/nix-copy-closure.html",
-  "#sec-nix-daemon": "command-ref/nix-daemon.html",
-  "#refsec-nix-env-install-examples": "command-ref/nix-env.html#examples",
-  "#rsec-nix-env-install": "command-ref/nix-env.html#operation---install",
-  "#rsec-nix-env-set": "command-ref/nix-env.html#operation---set",
-  "#rsec-nix-env-set-flag": "command-ref/nix-env.html#operation---set-flag",
-  "#rsec-nix-env-upgrade": "command-ref/nix-env.html#operation---upgrade",
-  "#sec-nix-env": "command-ref/nix-env.html",
-  "#ssec-version-comparisons": "command-ref/nix-env.html#versions",
-  "#sec-nix-hash": "command-ref/nix-hash.html",
-  "#sec-nix-instantiate": "command-ref/nix-instantiate.html",
-  "#sec-nix-prefetch-url": "command-ref/nix-prefetch-url.html",
-  "#sec-nix-shell": "command-ref/nix-shell.html",
-  "#ssec-nix-shell-shebang": "command-ref/nix-shell.html#use-as-a--interpreter",
-  "#nixref-queries": "command-ref/nix-store.html#queries",
-  "#opt-add-root": "command-ref/nix-store.html#opt-add-root",
-  "#refsec-nix-store-dump": "command-ref/nix-store.html#operation---dump",
-  "#refsec-nix-store-export": "command-ref/nix-store.html#operation---export",
-  "#refsec-nix-store-import": "command-ref/nix-store.html#operation---import",
-  "#refsec-nix-store-query": "command-ref/nix-store.html#operation---query",
-  "#refsec-nix-store-verify": "command-ref/nix-store.html#operation---verify",
-  "#rsec-nix-store-gc": "command-ref/nix-store.html#operation---gc",
-  "#rsec-nix-store-generate-binary-cache-key": "command-ref/nix-store.html#operation---generate-binary-cache-key",
-  "#rsec-nix-store-realise": "command-ref/nix-store.html#operation---realise",
-  "#rsec-nix-store-serve": "command-ref/nix-store.html#operation---serve",
-  "#sec-nix-store": "command-ref/nix-store.html",
-  "#opt-I": "command-ref/opt-common.html#opt-I",
-  "#opt-attr": "command-ref/opt-common.html#opt-attr",
-  "#opt-common": "command-ref/opt-common.html",
-  "#opt-cores": "command-ref/opt-common.html#opt-cores",
-  "#opt-log-format": "command-ref/opt-common.html#opt-log-format",
-  "#opt-max-jobs": "command-ref/opt-common.html#opt-max-jobs",
-  "#opt-max-silent-time": "command-ref/opt-common.html#opt-max-silent-time",
-  "#opt-timeout": "command-ref/opt-common.html#opt-timeout",
-  "#sec-common-options": "command-ref/opt-common.html",
-  "#ch-utilities": "command-ref/utilities.html",
-  "#chap-hacking": "contributing/hacking.html",
-  "#adv-attr-allowSubstitutes": "expressions/advanced-attributes.html#adv-attr-allowSubstitutes",
-  "#adv-attr-allowedReferences": "expressions/advanced-attributes.html#adv-attr-allowedReferences",
-  "#adv-attr-allowedRequisites": "expressions/advanced-attributes.html#adv-attr-allowedRequisites",
-  "#adv-attr-disallowedReferences": "expressions/advanced-attributes.html#adv-attr-disallowedReferences",
-  "#adv-attr-disallowedRequisites": "expressions/advanced-attributes.html#adv-attr-disallowedRequisites",
-  "#adv-attr-exportReferencesGraph": "expressions/advanced-attributes.html#adv-attr-exportReferencesGraph",
-  "#adv-attr-impureEnvVars": "expressions/advanced-attributes.html#adv-attr-impureEnvVars",
-  "#adv-attr-outputHash": "expressions/advanced-attributes.html#adv-attr-outputHash",
-  "#adv-attr-outputHashAlgo": "expressions/advanced-attributes.html#adv-attr-outputHashAlgo",
-  "#adv-attr-outputHashMode": "expressions/advanced-attributes.html#adv-attr-outputHashMode",
-  "#adv-attr-passAsFile": "expressions/advanced-attributes.html#adv-attr-passAsFile",
-  "#adv-attr-preferLocalBuild": "expressions/advanced-attributes.html#adv-attr-preferLocalBuild",
-  "#fixed-output-drvs": "expressions/advanced-attributes.html#adv-attr-outputHash",
-  "#sec-advanced-attributes": "expressions/advanced-attributes.html",
-  "#sec-arguments": "expressions/arguments-variables.html",
-  "#sec-build-script": "expressions/build-script.html",
-  "#builtin-abort": "expressions/builtins.html#builtins-abort",
-  "#builtin-add": "expressions/builtins.html#builtins-add",
-  "#builtin-all": "expressions/builtins.html#builtins-all",
-  "#builtin-any": "expressions/builtins.html#builtins-any",
-  "#builtin-attrNames": "expressions/builtins.html#builtins-attrNames",
-  "#builtin-attrValues": "expressions/builtins.html#builtins-attrValues",
-  "#builtin-baseNameOf": "expressions/builtins.html#builtins-baseNameOf",
-  "#builtin-bitAnd": "expressions/builtins.html#builtins-bitAnd",
-  "#builtin-bitOr": "expressions/builtins.html#builtins-bitOr",
-  "#builtin-bitXor": "expressions/builtins.html#builtins-bitXor",
-  "#builtin-builtins": "expressions/builtins.html#builtins-builtins",
-  "#builtin-compareVersions": "expressions/builtins.html#builtins-compareVersions",
-  "#builtin-concatLists": "expressions/builtins.html#builtins-concatLists",
-  "#builtin-concatStringsSep": "expressions/builtins.html#builtins-concatStringsSep",
-  "#builtin-currentSystem": "expressions/builtins.html#builtins-currentSystem",
-  "#builtin-deepSeq": "expressions/builtins.html#builtins-deepSeq",
-  "#builtin-derivation": "expressions/builtins.html#builtins-derivation",
-  "#builtin-dirOf": "expressions/builtins.html#builtins-dirOf",
-  "#builtin-div": "expressions/builtins.html#builtins-div",
-  "#builtin-elem": "expressions/builtins.html#builtins-elem",
-  "#builtin-elemAt": "expressions/builtins.html#builtins-elemAt",
-  "#builtin-fetchGit": "expressions/builtins.html#builtins-fetchGit",
-  "#builtin-fetchTarball": "expressions/builtins.html#builtins-fetchTarball",
-  "#builtin-fetchurl": "expressions/builtins.html#builtins-fetchurl",
-  "#builtin-filterSource": "expressions/builtins.html#builtins-filterSource",
-  "#builtin-foldl-prime": "expressions/builtins.html#builtins-foldl-prime",
-  "#builtin-fromJSON": "expressions/builtins.html#builtins-fromJSON",
-  "#builtin-functionArgs": "expressions/builtins.html#builtins-functionArgs",
-  "#builtin-genList": "expressions/builtins.html#builtins-genList",
-  "#builtin-getAttr": "expressions/builtins.html#builtins-getAttr",
-  "#builtin-getEnv": "expressions/builtins.html#builtins-getEnv",
-  "#builtin-hasAttr": "expressions/builtins.html#builtins-hasAttr",
-  "#builtin-hashFile": "expressions/builtins.html#builtins-hashFile",
-  "#builtin-hashString": "expressions/builtins.html#builtins-hashString",
-  "#builtin-head": "expressions/builtins.html#builtins-head",
-  "#builtin-import": "expressions/builtins.html#builtins-import",
-  "#builtin-intersectAttrs": "expressions/builtins.html#builtins-intersectAttrs",
-  "#builtin-isAttrs": "expressions/builtins.html#builtins-isAttrs",
-  "#builtin-isBool": "expressions/builtins.html#builtins-isBool",
-  "#builtin-isFloat": "expressions/builtins.html#builtins-isFloat",
-  "#builtin-isFunction": "expressions/builtins.html#builtins-isFunction",
-  "#builtin-isInt": "expressions/builtins.html#builtins-isInt",
-  "#builtin-isList": "expressions/builtins.html#builtins-isList",
-  "#builtin-isNull": "expressions/builtins.html#builtins-isNull",
-  "#builtin-isString": "expressions/builtins.html#builtins-isString",
-  "#builtin-length": "expressions/builtins.html#builtins-length",
-  "#builtin-lessThan": "expressions/builtins.html#builtins-lessThan",
-  "#builtin-listToAttrs": "expressions/builtins.html#builtins-listToAttrs",
-  "#builtin-map": "expressions/builtins.html#builtins-map",
-  "#builtin-match": "expressions/builtins.html#builtins-match",
-  "#builtin-mul": "expressions/builtins.html#builtins-mul",
-  "#builtin-parseDrvName": "expressions/builtins.html#builtins-parseDrvName",
-  "#builtin-path": "expressions/builtins.html#builtins-path",
-  "#builtin-pathExists": "expressions/builtins.html#builtins-pathExists",
-  "#builtin-placeholder": "expressions/builtins.html#builtins-placeholder",
-  "#builtin-readDir": "expressions/builtins.html#builtins-readDir",
-  "#builtin-readFile": "expressions/builtins.html#builtins-readFile",
-  "#builtin-removeAttrs": "expressions/builtins.html#builtins-removeAttrs",
-  "#builtin-replaceStrings": "expressions/builtins.html#builtins-replaceStrings",
-  "#builtin-seq": "expressions/builtins.html#builtins-seq",
-  "#builtin-sort": "expressions/builtins.html#builtins-sort",
-  "#builtin-split": "expressions/builtins.html#builtins-split",
-  "#builtin-splitVersion": "expressions/builtins.html#builtins-splitVersion",
-  "#builtin-stringLength": "expressions/builtins.html#builtins-stringLength",
-  "#builtin-sub": "expressions/builtins.html#builtins-sub",
-  "#builtin-substring": "expressions/builtins.html#builtins-substring",
-  "#builtin-tail": "expressions/builtins.html#builtins-tail",
-  "#builtin-throw": "expressions/builtins.html#builtins-throw",
-  "#builtin-toFile": "expressions/builtins.html#builtins-toFile",
-  "#builtin-toJSON": "expressions/builtins.html#builtins-toJSON",
-  "#builtin-toPath": "expressions/builtins.html#builtins-toPath",
-  "#builtin-toString": "expressions/builtins.html#builtins-toString",
-  "#builtin-toXML": "expressions/builtins.html#builtins-toXML",
-  "#builtin-trace": "expressions/builtins.html#builtins-trace",
-  "#builtin-tryEval": "expressions/builtins.html#builtins-tryEval",
-  "#builtin-typeOf": "expressions/builtins.html#builtins-typeOf",
-  "#ssec-builtins": "expressions/builtins.html",
-  "#attr-system": "expressions/derivations.html#attr-system",
-  "#ssec-derivation": "expressions/derivations.html",
-  "#ch-expression-language": "expressions/expression-language.html",
-  "#sec-expression-syntax": "expressions/expression-syntax.html",
-  "#sec-generic-builder": "expressions/generic-builder.html",
-  "#sec-constructs": "expressions/language-constructs.html",
-  "#sect-let-expressions": "expressions/language-constructs.html#let-expressions",
-  "#ss-functions": "expressions/language-constructs.html#functions",
-  "#sec-language-operators": "expressions/language-operators.html",
-  "#table-operators": "expressions/language-operators.html",
-  "#ssec-values": "expressions/language-values.html",
-  "#sec-building-simple": "expressions/simple-building-testing.html",
-  "#ch-simple-expression": "expressions/simple-expression.html",
-  "#chap-writing-nix-expressions": "expressions/writing-nix-expressions.html",
-  "#gloss-closure": "glossary.html#gloss-closure",
-  "#gloss-derivation": "glossary.html#gloss-derivation",
-  "#gloss-deriver": "glossary.html#gloss-deriver",
-  "#gloss-nar": "glossary.html#gloss-nar",
-  "#gloss-output-path": "glossary.html#gloss-output-path",
-  "#gloss-profile": "glossary.html#gloss-profile",
-  "#gloss-reachable": "glossary.html#gloss-reachable",
-  "#gloss-reference": "glossary.html#gloss-reference",
-  "#gloss-substitute": "glossary.html#gloss-substitute",
-  "#gloss-user-env": "glossary.html#gloss-user-env",
-  "#gloss-validity": "glossary.html#gloss-validity",
-  "#part-glossary": "glossary.html",
-  "#sec-building-source": "installation/building-source.html",
-  "#ch-env-variables": "installation/env-variables.html",
-  "#sec-installer-proxy-settings": "installation/env-variables.html#proxy-environment-variables",
-  "#sec-nix-ssl-cert-file": "installation/env-variables.html#nix_ssl_cert_file",
-  "#sec-nix-ssl-cert-file-with-nix-daemon-and-macos": "installation/env-variables.html#nix_ssl_cert_file-with-macos-and-the-nix-daemon",
-  "#chap-installation": "installation/installation.html",
-  "#ch-installing-binary": "installation/installing-binary.html",
-  "#sect-macos-installation": "installation/installing-binary.html#macos-installation",
-  "#sect-macos-installation-change-store-prefix": "installation/installing-binary.html#macos-installation",
-  "#sect-macos-installation-encrypted-volume": "installation/installing-binary.html#macos-installation",
-  "#sect-macos-installation-recommended-notes": "installation/installing-binary.html#macos-installation",
-  "#sect-macos-installation-symlink": "installation/installing-binary.html#macos-installation",
-  "#sect-multi-user-installation": "installation/installing-binary.html#multi-user-installation",
-  "#sect-nix-install-binary-tarball": "installation/installing-binary.html#installing-from-a-binary-tarball",
-  "#sect-nix-install-pinned-version-url": "installation/installing-binary.html#installing-a-pinned-nix-version-from-a-url",
-  "#sect-single-user-installation": "installation/installing-binary.html#single-user-installation",
-  "#ch-installing-source": "installation/installing-source.html",
-  "#ssec-multi-user": "installation/multi-user.html",
-  "#ch-nix-security": "installation/nix-security.html",
-  "#sec-obtaining-source": "installation/obtaining-source.html",
-  "#sec-prerequisites-source": "installation/prerequisites-source.html",
-  "#sec-single-user": "installation/single-user.html",
-  "#ch-supported-platforms": "installation/supported-platforms.html",
-  "#ch-upgrading-nix": "installation/upgrading.html",
-  "#ch-about-nix": "introduction.html",
-  "#chap-introduction": "introduction.html",
-  "#ch-basic-package-mgmt": "package-management/basic-package-mgmt.html",
-  "#ssec-binary-cache-substituter": "package-management/binary-cache-substituter.html",
-  "#sec-channels": "package-management/channels.html",
-  "#ssec-copy-closure": "package-management/copy-closure.html",
-  "#sec-garbage-collection": "package-management/garbage-collection.html",
-  "#ssec-gc-roots": "package-management/garbage-collector-roots.html",
-  "#chap-package-management": "package-management/package-management.html",
-  "#sec-profiles": "package-management/profiles.html",
-  "#ssec-s3-substituter": "package-management/s3-substituter.html",
-  "#ssec-s3-substituter-anonymous-reads": "package-management/s3-substituter.html#anonymous-reads-to-your-s3-compatible-binary-cache",
-  "#ssec-s3-substituter-authenticated-reads": "package-management/s3-substituter.html#authenticated-reads-to-your-s3-binary-cache",
-  "#ssec-s3-substituter-authenticated-writes": "package-management/s3-substituter.html#authenticated-writes-to-your-s3-compatible-binary-cache",
-  "#sec-sharing-packages": "package-management/sharing-packages.html",
-  "#ssec-ssh-substituter": "package-management/ssh-substituter.html",
-  "#chap-quick-start": "quick-start.html",
-  "#sec-relnotes": "release-notes/release-notes.html",
-  "#ch-relnotes-0.10.1": "release-notes/rl-0.10.1.html",
-  "#ch-relnotes-0.10": "release-notes/rl-0.10.html",
-  "#ssec-relnotes-0.11": "release-notes/rl-0.11.html",
-  "#ssec-relnotes-0.12": "release-notes/rl-0.12.html",
-  "#ssec-relnotes-0.13": "release-notes/rl-0.13.html",
-  "#ssec-relnotes-0.14": "release-notes/rl-0.14.html",
-  "#ssec-relnotes-0.15": "release-notes/rl-0.15.html",
-  "#ssec-relnotes-0.16": "release-notes/rl-0.16.html",
-  "#ch-relnotes-0.5": "release-notes/rl-0.5.html",
-  "#ch-relnotes-0.6": "release-notes/rl-0.6.html",
-  "#ch-relnotes-0.7": "release-notes/rl-0.7.html",
-  "#ch-relnotes-0.8.1": "release-notes/rl-0.8.1.html",
-  "#ch-relnotes-0.8": "release-notes/rl-0.8.html",
-  "#ch-relnotes-0.9.1": "release-notes/rl-0.9.1.html",
-  "#ch-relnotes-0.9.2": "release-notes/rl-0.9.2.html",
-  "#ch-relnotes-0.9": "release-notes/rl-0.9.html",
-  "#ssec-relnotes-1.0": "release-notes/rl-1.0.html",
-  "#ssec-relnotes-1.1": "release-notes/rl-1.1.html",
-  "#ssec-relnotes-1.10": "release-notes/rl-1.10.html",
-  "#ssec-relnotes-1.11.10": "release-notes/rl-1.11.10.html",
-  "#ssec-relnotes-1.11": "release-notes/rl-1.11.html",
-  "#ssec-relnotes-1.2": "release-notes/rl-1.2.html",
-  "#ssec-relnotes-1.3": "release-notes/rl-1.3.html",
-  "#ssec-relnotes-1.4": "release-notes/rl-1.4.html",
-  "#ssec-relnotes-1.5.1": "release-notes/rl-1.5.1.html",
-  "#ssec-relnotes-1.5.2": "release-notes/rl-1.5.2.html",
-  "#ssec-relnotes-1.5": "release-notes/rl-1.5.html",
-  "#ssec-relnotes-1.6.1": "release-notes/rl-1.6.1.html",
-  "#ssec-relnotes-1.6.0": "release-notes/rl-1.6.html",
-  "#ssec-relnotes-1.7": "release-notes/rl-1.7.html",
-  "#ssec-relnotes-1.8": "release-notes/rl-1.8.html",
-  "#ssec-relnotes-1.9": "release-notes/rl-1.9.html",
-  "#ssec-relnotes-2.0": "release-notes/rl-2.0.html",
-  "#ssec-relnotes-2.1": "release-notes/rl-2.1.html",
-  "#ssec-relnotes-2.2": "release-notes/rl-2.2.html",
-  "#ssec-relnotes-2.3": "release-notes/rl-2.3.html"
+// redirect rules for anchors ensure backwards compatibility of URLs.
+// this must be done on the client side, as web servers do not see the anchor part of the URL.
+
+// redirections are declared as follows:
+// each entry has as its key a path matching the requested URL path, relative to the mdBook document root.
+//
+//     IMPORTANT: it must specify the full path with file name and suffix
+//
+// each entry is itself a set of key-value pairs, where
+// - keys are anchors on the matched path.
+// - values are redirection targets relative to the current path.
+
+const redirects = {
+ "index.html": {
+    "part-advanced-topics": "advanced-topics/advanced-topics.html",
+    "chap-tuning-cores-and-jobs": "advanced-topics/cores-vs-jobs.html",
+    "chap-diff-hook": "advanced-topics/diff-hook.html",
+    "check-dirs-are-unregistered": "advanced-topics/diff-hook.html#check-dirs-are-unregistered",
+    "chap-distributed-builds": "advanced-topics/distributed-builds.html",
+    "chap-post-build-hook": "advanced-topics/post-build-hook.html",
+    "chap-post-build-hook-caveats": "advanced-topics/post-build-hook.html#implementation-caveats",
+    "part-command-ref": "command-ref/command-ref.html",
+    "conf-allow-import-from-derivation": "command-ref/conf-file.html#conf-allow-import-from-derivation",
+    "conf-allow-new-privileges": "command-ref/conf-file.html#conf-allow-new-privileges",
+    "conf-allowed-uris": "command-ref/conf-file.html#conf-allowed-uris",
+    "conf-allowed-users": "command-ref/conf-file.html#conf-allowed-users",
+    "conf-auto-optimise-store": "command-ref/conf-file.html#conf-auto-optimise-store",
+    "conf-binary-cache-public-keys": "command-ref/conf-file.html#conf-binary-cache-public-keys",
+    "conf-binary-caches": "command-ref/conf-file.html#conf-binary-caches",
+    "conf-build-compress-log": "command-ref/conf-file.html#conf-build-compress-log",
+    "conf-build-cores": "command-ref/conf-file.html#conf-build-cores",
+    "conf-build-extra-chroot-dirs": "command-ref/conf-file.html#conf-build-extra-chroot-dirs",
+    "conf-build-extra-sandbox-paths": "command-ref/conf-file.html#conf-build-extra-sandbox-paths",
+    "conf-build-fallback": "command-ref/conf-file.html#conf-build-fallback",
+    "conf-build-max-jobs": "command-ref/conf-file.html#conf-build-max-jobs",
+    "conf-build-max-log-size": "command-ref/conf-file.html#conf-build-max-log-size",
+    "conf-build-max-silent-time": "command-ref/conf-file.html#conf-build-max-silent-time",
+    "conf-build-timeout": "command-ref/conf-file.html#conf-build-timeout",
+    "conf-build-use-chroot": "command-ref/conf-file.html#conf-build-use-chroot",
+    "conf-build-use-sandbox": "command-ref/conf-file.html#conf-build-use-sandbox",
+    "conf-build-use-substitutes": "command-ref/conf-file.html#conf-build-use-substitutes",
+    "conf-build-users-group": "command-ref/conf-file.html#conf-build-users-group",
+    "conf-builders": "command-ref/conf-file.html#conf-builders",
+    "conf-builders-use-substitutes": "command-ref/conf-file.html#conf-builders-use-substitutes",
+    "conf-compress-build-log": "command-ref/conf-file.html#conf-compress-build-log",
+    "conf-connect-timeout": "command-ref/conf-file.html#conf-connect-timeout",
+    "conf-cores": "command-ref/conf-file.html#conf-cores",
+    "conf-diff-hook": "command-ref/conf-file.html#conf-diff-hook",
+    "conf-env-keep-derivations": "command-ref/conf-file.html#conf-env-keep-derivations",
+    "conf-extra-binary-caches": "command-ref/conf-file.html#conf-extra-binary-caches",
+    "conf-extra-platforms": "command-ref/conf-file.html#conf-extra-platforms",
+    "conf-extra-sandbox-paths": "command-ref/conf-file.html#conf-extra-sandbox-paths",
+    "conf-extra-substituters": "command-ref/conf-file.html#conf-extra-substituters",
+    "conf-fallback": "command-ref/conf-file.html#conf-fallback",
+    "conf-fsync-metadata": "command-ref/conf-file.html#conf-fsync-metadata",
+    "conf-gc-keep-derivations": "command-ref/conf-file.html#conf-gc-keep-derivations",
+    "conf-gc-keep-outputs": "command-ref/conf-file.html#conf-gc-keep-outputs",
+    "conf-hashed-mirrors": "command-ref/conf-file.html#conf-hashed-mirrors",
+    "conf-http-connections": "command-ref/conf-file.html#conf-http-connections",
+    "conf-keep-build-log": "command-ref/conf-file.html#conf-keep-build-log",
+    "conf-keep-derivations": "command-ref/conf-file.html#conf-keep-derivations",
+    "conf-keep-env-derivations": "command-ref/conf-file.html#conf-keep-env-derivations",
+    "conf-keep-outputs": "command-ref/conf-file.html#conf-keep-outputs",
+    "conf-max-build-log-size": "command-ref/conf-file.html#conf-max-build-log-size",
+    "conf-max-free": "command-ref/conf-file.html#conf-max-free",
+    "conf-max-jobs": "command-ref/conf-file.html#conf-max-jobs",
+    "conf-max-silent-time": "command-ref/conf-file.html#conf-max-silent-time",
+    "conf-min-free": "command-ref/conf-file.html#conf-min-free",
+    "conf-narinfo-cache-negative-ttl": "command-ref/conf-file.html#conf-narinfo-cache-negative-ttl",
+    "conf-narinfo-cache-positive-ttl": "command-ref/conf-file.html#conf-narinfo-cache-positive-ttl",
+    "conf-netrc-file": "command-ref/conf-file.html#conf-netrc-file",
+    "conf-plugin-files": "command-ref/conf-file.html#conf-plugin-files",
+    "conf-post-build-hook": "command-ref/conf-file.html#conf-post-build-hook",
+    "conf-pre-build-hook": "command-ref/conf-file.html#conf-pre-build-hook",
+    "conf-require-sigs": "command-ref/conf-file.html#conf-require-sigs",
+    "conf-restrict-eval": "command-ref/conf-file.html#conf-restrict-eval",
+    "conf-run-diff-hook": "command-ref/conf-file.html#conf-run-diff-hook",
+    "conf-sandbox": "command-ref/conf-file.html#conf-sandbox",
+    "conf-sandbox-dev-shm-size": "command-ref/conf-file.html#conf-sandbox-dev-shm-size",
+    "conf-sandbox-paths": "command-ref/conf-file.html#conf-sandbox-paths",
+    "conf-secret-key-files": "command-ref/conf-file.html#conf-secret-key-files",
+    "conf-show-trace": "command-ref/conf-file.html#conf-show-trace",
+    "conf-stalled-download-timeout": "command-ref/conf-file.html#conf-stalled-download-timeout",
+    "conf-substitute": "command-ref/conf-file.html#conf-substitute",
+    "conf-substituters": "command-ref/conf-file.html#conf-substituters",
+    "conf-system": "command-ref/conf-file.html#conf-system",
+    "conf-system-features": "command-ref/conf-file.html#conf-system-features",
+    "conf-tarball-ttl": "command-ref/conf-file.html#conf-tarball-ttl",
+    "conf-timeout": "command-ref/conf-file.html#conf-timeout",
+    "conf-trace-function-calls": "command-ref/conf-file.html#conf-trace-function-calls",
+    "conf-trusted-binary-caches": "command-ref/conf-file.html#conf-trusted-binary-caches",
+    "conf-trusted-public-keys": "command-ref/conf-file.html#conf-trusted-public-keys",
+    "conf-trusted-substituters": "command-ref/conf-file.html#conf-trusted-substituters",
+    "conf-trusted-users": "command-ref/conf-file.html#conf-trusted-users",
+    "extra-sandbox-paths": "command-ref/conf-file.html#extra-sandbox-paths",
+    "sec-conf-file": "command-ref/conf-file.html",
+    "env-NIX_PATH": "command-ref/env-common.html#env-NIX_PATH",
+    "env-common": "command-ref/env-common.html",
+    "envar-remote": "command-ref/env-common.html#env-NIX_REMOTE",
+    "sec-common-env": "command-ref/env-common.html",
+    "ch-files": "command-ref/files.html",
+    "ch-main-commands": "command-ref/main-commands.html",
+    "opt-out-link": "command-ref/nix-build.html#opt-out-link",
+    "sec-nix-build": "command-ref/nix-build.html",
+    "sec-nix-channel": "command-ref/nix-channel.html",
+    "sec-nix-collect-garbage": "command-ref/nix-collect-garbage.html",
+    "sec-nix-copy-closure": "command-ref/nix-copy-closure.html",
+    "sec-nix-daemon": "command-ref/nix-daemon.html",
+    "refsec-nix-env-install-examples": "command-ref/nix-env.html#examples",
+    "rsec-nix-env-install": "command-ref/nix-env.html#operation---install",
+    "rsec-nix-env-set": "command-ref/nix-env.html#operation---set",
+    "rsec-nix-env-set-flag": "command-ref/nix-env.html#operation---set-flag",
+    "rsec-nix-env-upgrade": "command-ref/nix-env.html#operation---upgrade",
+    "sec-nix-env": "command-ref/nix-env.html",
+    "ssec-version-comparisons": "command-ref/nix-env.html#versions",
+    "sec-nix-hash": "command-ref/nix-hash.html",
+    "sec-nix-instantiate": "command-ref/nix-instantiate.html",
+    "sec-nix-prefetch-url": "command-ref/nix-prefetch-url.html",
+    "sec-nix-shell": "command-ref/nix-shell.html",
+    "ssec-nix-shell-shebang": "command-ref/nix-shell.html#use-as-a--interpreter",
+    "nixref-queries": "command-ref/nix-store.html#queries",
+    "opt-add-root": "command-ref/nix-store.html#opt-add-root",
+    "refsec-nix-store-dump": "command-ref/nix-store.html#operation---dump",
+    "refsec-nix-store-export": "command-ref/nix-store.html#operation---export",
+    "refsec-nix-store-import": "command-ref/nix-store.html#operation---import",
+    "refsec-nix-store-query": "command-ref/nix-store.html#operation---query",
+    "refsec-nix-store-verify": "command-ref/nix-store.html#operation---verify",
+    "rsec-nix-store-gc": "command-ref/nix-store.html#operation---gc",
+    "rsec-nix-store-generate-binary-cache-key": "command-ref/nix-store.html#operation---generate-binary-cache-key",
+    "rsec-nix-store-realise": "command-ref/nix-store.html#operation---realise",
+    "rsec-nix-store-serve": "command-ref/nix-store.html#operation---serve",
+    "sec-nix-store": "command-ref/nix-store.html",
+    "opt-I": "command-ref/opt-common.html#opt-I",
+    "opt-attr": "command-ref/opt-common.html#opt-attr",
+    "opt-common": "command-ref/opt-common.html",
+    "opt-cores": "command-ref/opt-common.html#opt-cores",
+    "opt-log-format": "command-ref/opt-common.html#opt-log-format",
+    "opt-max-jobs": "command-ref/opt-common.html#opt-max-jobs",
+    "opt-max-silent-time": "command-ref/opt-common.html#opt-max-silent-time",
+    "opt-timeout": "command-ref/opt-common.html#opt-timeout",
+    "sec-common-options": "command-ref/opt-common.html",
+    "ch-utilities": "command-ref/utilities.html",
+    "chap-hacking": "contributing/hacking.html",
+    "adv-attr-allowSubstitutes": "language/advanced-attributes.html#adv-attr-allowSubstitutes",
+    "adv-attr-allowedReferences": "language/advanced-attributes.html#adv-attr-allowedReferences",
+    "adv-attr-allowedRequisites": "language/advanced-attributes.html#adv-attr-allowedRequisites",
+    "adv-attr-disallowedReferences": "language/advanced-attributes.html#adv-attr-disallowedReferences",
+    "adv-attr-disallowedRequisites": "language/advanced-attributes.html#adv-attr-disallowedRequisites",
+    "adv-attr-exportReferencesGraph": "language/advanced-attributes.html#adv-attr-exportReferencesGraph",
+    "adv-attr-impureEnvVars": "language/advanced-attributes.html#adv-attr-impureEnvVars",
+    "adv-attr-outputHash": "language/advanced-attributes.html#adv-attr-outputHash",
+    "adv-attr-outputHashAlgo": "language/advanced-attributes.html#adv-attr-outputHashAlgo",
+    "adv-attr-outputHashMode": "language/advanced-attributes.html#adv-attr-outputHashMode",
+    "adv-attr-passAsFile": "language/advanced-attributes.html#adv-attr-passAsFile",
+    "adv-attr-preferLocalBuild": "language/advanced-attributes.html#adv-attr-preferLocalBuild",
+    "fixed-output-drvs": "language/advanced-attributes.html#adv-attr-outputHash",
+    "sec-advanced-attributes": "language/advanced-attributes.html",
+    "builtin-abort": "language/builtins.html#builtins-abort",
+    "builtin-add": "language/builtins.html#builtins-add",
+    "builtin-all": "language/builtins.html#builtins-all",
+    "builtin-any": "language/builtins.html#builtins-any",
+    "builtin-attrNames": "language/builtins.html#builtins-attrNames",
+    "builtin-attrValues": "language/builtins.html#builtins-attrValues",
+    "builtin-baseNameOf": "language/builtins.html#builtins-baseNameOf",
+    "builtin-bitAnd": "language/builtins.html#builtins-bitAnd",
+    "builtin-bitOr": "language/builtins.html#builtins-bitOr",
+    "builtin-bitXor": "language/builtins.html#builtins-bitXor",
+    "builtin-builtins": "language/builtins.html#builtins-builtins",
+    "builtin-compareVersions": "language/builtins.html#builtins-compareVersions",
+    "builtin-concatLists": "language/builtins.html#builtins-concatLists",
+    "builtin-concatStringsSep": "language/builtins.html#builtins-concatStringsSep",
+    "builtin-currentSystem": "language/builtins.html#builtins-currentSystem",
+    "builtin-deepSeq": "language/builtins.html#builtins-deepSeq",
+    "builtin-derivation": "language/builtins.html#builtins-derivation",
+    "builtin-dirOf": "language/builtins.html#builtins-dirOf",
+    "builtin-div": "language/builtins.html#builtins-div",
+    "builtin-elem": "language/builtins.html#builtins-elem",
+    "builtin-elemAt": "language/builtins.html#builtins-elemAt",
+    "builtin-fetchGit": "language/builtins.html#builtins-fetchGit",
+    "builtin-fetchTarball": "language/builtins.html#builtins-fetchTarball",
+    "builtin-fetchurl": "language/builtins.html#builtins-fetchurl",
+    "builtin-filterSource": "language/builtins.html#builtins-filterSource",
+    "builtin-foldl-prime": "language/builtins.html#builtins-foldl-prime",
+    "builtin-fromJSON": "language/builtins.html#builtins-fromJSON",
+    "builtin-functionArgs": "language/builtins.html#builtins-functionArgs",
+    "builtin-genList": "language/builtins.html#builtins-genList",
+    "builtin-getAttr": "language/builtins.html#builtins-getAttr",
+    "builtin-getEnv": "language/builtins.html#builtins-getEnv",
+    "builtin-hasAttr": "language/builtins.html#builtins-hasAttr",
+    "builtin-hashFile": "language/builtins.html#builtins-hashFile",
+    "builtin-hashString": "language/builtins.html#builtins-hashString",
+    "builtin-head": "language/builtins.html#builtins-head",
+    "builtin-import": "language/builtins.html#builtins-import",
+    "builtin-intersectAttrs": "language/builtins.html#builtins-intersectAttrs",
+    "builtin-isAttrs": "language/builtins.html#builtins-isAttrs",
+    "builtin-isBool": "language/builtins.html#builtins-isBool",
+    "builtin-isFloat": "language/builtins.html#builtins-isFloat",
+    "builtin-isFunction": "language/builtins.html#builtins-isFunction",
+    "builtin-isInt": "language/builtins.html#builtins-isInt",
+    "builtin-isList": "language/builtins.html#builtins-isList",
+    "builtin-isNull": "language/builtins.html#builtins-isNull",
+    "builtin-isString": "language/builtins.html#builtins-isString",
+    "builtin-length": "language/builtins.html#builtins-length",
+    "builtin-lessThan": "language/builtins.html#builtins-lessThan",
+    "builtin-listToAttrs": "language/builtins.html#builtins-listToAttrs",
+    "builtin-map": "language/builtins.html#builtins-map",
+    "builtin-match": "language/builtins.html#builtins-match",
+    "builtin-mul": "language/builtins.html#builtins-mul",
+    "builtin-parseDrvName": "language/builtins.html#builtins-parseDrvName",
+    "builtin-path": "language/builtins.html#builtins-path",
+    "builtin-pathExists": "language/builtins.html#builtins-pathExists",
+    "builtin-placeholder": "language/builtins.html#builtins-placeholder",
+    "builtin-readDir": "language/builtins.html#builtins-readDir",
+    "builtin-readFile": "language/builtins.html#builtins-readFile",
+    "builtin-removeAttrs": "language/builtins.html#builtins-removeAttrs",
+    "builtin-replaceStrings": "language/builtins.html#builtins-replaceStrings",
+    "builtin-seq": "language/builtins.html#builtins-seq",
+    "builtin-sort": "language/builtins.html#builtins-sort",
+    "builtin-split": "language/builtins.html#builtins-split",
+    "builtin-splitVersion": "language/builtins.html#builtins-splitVersion",
+    "builtin-stringLength": "language/builtins.html#builtins-stringLength",
+    "builtin-sub": "language/builtins.html#builtins-sub",
+    "builtin-substring": "language/builtins.html#builtins-substring",
+    "builtin-tail": "language/builtins.html#builtins-tail",
+    "builtin-throw": "language/builtins.html#builtins-throw",
+    "builtin-toFile": "language/builtins.html#builtins-toFile",
+    "builtin-toJSON": "language/builtins.html#builtins-toJSON",
+    "builtin-toPath": "language/builtins.html#builtins-toPath",
+    "builtin-toString": "language/builtins.html#builtins-toString",
+    "builtin-toXML": "language/builtins.html#builtins-toXML",
+    "builtin-trace": "language/builtins.html#builtins-trace",
+    "builtin-tryEval": "language/builtins.html#builtins-tryEval",
+    "builtin-typeOf": "language/builtins.html#builtins-typeOf",
+    "ssec-builtins": "language/builtins.html",
+    "attr-system": "language/derivations.html#attr-system",
+    "ssec-derivation": "language/derivations.html",
+    "ch-expression-language": "language/index.html",
+    "sec-constructs": "language/constructs.html",
+    "sect-let-language": "language/constructs.html#let-language",
+    "ss-functions": "language/constructs.html#functions",
+    "sec-language-operators": "language/operators.html",
+    "table-operators": "language/operators.html",
+    "ssec-values": "language/values.html",
+    "gloss-closure": "glossary.html#gloss-closure",
+    "gloss-derivation": "glossary.html#gloss-derivation",
+    "gloss-deriver": "glossary.html#gloss-deriver",
+    "gloss-nar": "glossary.html#gloss-nar",
+    "gloss-output-path": "glossary.html#gloss-output-path",
+    "gloss-profile": "glossary.html#gloss-profile",
+    "gloss-reachable": "glossary.html#gloss-reachable",
+    "gloss-reference": "glossary.html#gloss-reference",
+    "gloss-substitute": "glossary.html#gloss-substitute",
+    "gloss-user-env": "glossary.html#gloss-user-env",
+    "gloss-validity": "glossary.html#gloss-validity",
+    "part-glossary": "glossary.html",
+    "sec-building-source": "installation/building-source.html",
+    "ch-env-variables": "installation/env-variables.html",
+    "sec-installer-proxy-settings": "installation/env-variables.html#proxy-environment-variables",
+    "sec-nix-ssl-cert-file": "installation/env-variables.html#nix_ssl_cert_file",
+    "sec-nix-ssl-cert-file-with-nix-daemon-and-macos": "installation/env-variables.html#nix_ssl_cert_file-with-macos-and-the-nix-daemon",
+    "chap-installation": "installation/installation.html",
+    "ch-installing-binary": "installation/installing-binary.html",
+    "sect-macos-installation": "installation/installing-binary.html#macos-installation",
+    "sect-macos-installation-change-store-prefix": "installation/installing-binary.html#macos-installation",
+    "sect-macos-installation-encrypted-volume": "installation/installing-binary.html#macos-installation",
+    "sect-macos-installation-recommended-notes": "installation/installing-binary.html#macos-installation",
+    "sect-macos-installation-symlink": "installation/installing-binary.html#macos-installation",
+    "sect-multi-user-installation": "installation/installing-binary.html#multi-user-installation",
+    "sect-nix-install-binary-tarball": "installation/installing-binary.html#installing-from-a-binary-tarball",
+    "sect-nix-install-pinned-version-url": "installation/installing-binary.html#installing-a-pinned-nix-version-from-a-url",
+    "sect-single-user-installation": "installation/installing-binary.html#single-user-installation",
+    "ch-installing-source": "installation/installing-source.html",
+    "ssec-multi-user": "installation/multi-user.html",
+    "ch-nix-security": "installation/nix-security.html",
+    "sec-obtaining-source": "installation/obtaining-source.html",
+    "sec-prerequisites-source": "installation/prerequisites-source.html",
+    "sec-single-user": "installation/single-user.html",
+    "ch-supported-platforms": "installation/supported-platforms.html",
+    "ch-upgrading-nix": "installation/upgrading.html",
+    "ch-about-nix": "introduction.html",
+    "chap-introduction": "introduction.html",
+    "ch-basic-package-mgmt": "package-management/basic-package-mgmt.html",
+    "ssec-binary-cache-substituter": "package-management/binary-cache-substituter.html",
+    "sec-channels": "package-management/channels.html",
+    "ssec-copy-closure": "package-management/copy-closure.html",
+    "sec-garbage-collection": "package-management/garbage-collection.html",
+    "ssec-gc-roots": "package-management/garbage-collector-roots.html",
+    "chap-package-management": "package-management/package-management.html",
+    "sec-profiles": "package-management/profiles.html",
+    "ssec-s3-substituter": "package-management/s3-substituter.html",
+    "ssec-s3-substituter-anonymous-reads": "package-management/s3-substituter.html#anonymous-reads-to-your-s3-compatible-binary-cache",
+    "ssec-s3-substituter-authenticated-reads": "package-management/s3-substituter.html#authenticated-reads-to-your-s3-binary-cache",
+    "ssec-s3-substituter-authenticated-writes": "package-management/s3-substituter.html#authenticated-writes-to-your-s3-compatible-binary-cache",
+    "sec-sharing-packages": "package-management/sharing-packages.html",
+    "ssec-ssh-substituter": "package-management/ssh-substituter.html",
+    "chap-quick-start": "quick-start.html",
+    "sec-relnotes": "release-notes/release-notes.html",
+    "ch-relnotes-0.10.1": "release-notes/rl-0.10.1.html",
+    "ch-relnotes-0.10": "release-notes/rl-0.10.html",
+    "ssec-relnotes-0.11": "release-notes/rl-0.11.html",
+    "ssec-relnotes-0.12": "release-notes/rl-0.12.html",
+    "ssec-relnotes-0.13": "release-notes/rl-0.13.html",
+    "ssec-relnotes-0.14": "release-notes/rl-0.14.html",
+    "ssec-relnotes-0.15": "release-notes/rl-0.15.html",
+    "ssec-relnotes-0.16": "release-notes/rl-0.16.html",
+    "ch-relnotes-0.5": "release-notes/rl-0.5.html",
+    "ch-relnotes-0.6": "release-notes/rl-0.6.html",
+    "ch-relnotes-0.7": "release-notes/rl-0.7.html",
+    "ch-relnotes-0.8.1": "release-notes/rl-0.8.1.html",
+    "ch-relnotes-0.8": "release-notes/rl-0.8.html",
+    "ch-relnotes-0.9.1": "release-notes/rl-0.9.1.html",
+    "ch-relnotes-0.9.2": "release-notes/rl-0.9.2.html",
+    "ch-relnotes-0.9": "release-notes/rl-0.9.html",
+    "ssec-relnotes-1.0": "release-notes/rl-1.0.html",
+    "ssec-relnotes-1.1": "release-notes/rl-1.1.html",
+    "ssec-relnotes-1.10": "release-notes/rl-1.10.html",
+    "ssec-relnotes-1.11.10": "release-notes/rl-1.11.10.html",
+    "ssec-relnotes-1.11": "release-notes/rl-1.11.html",
+    "ssec-relnotes-1.2": "release-notes/rl-1.2.html",
+    "ssec-relnotes-1.3": "release-notes/rl-1.3.html",
+    "ssec-relnotes-1.4": "release-notes/rl-1.4.html",
+    "ssec-relnotes-1.5.1": "release-notes/rl-1.5.1.html",
+    "ssec-relnotes-1.5.2": "release-notes/rl-1.5.2.html",
+    "ssec-relnotes-1.5": "release-notes/rl-1.5.html",
+    "ssec-relnotes-1.6.1": "release-notes/rl-1.6.1.html",
+    "ssec-relnotes-1.6.0": "release-notes/rl-1.6.html",
+    "ssec-relnotes-1.7": "release-notes/rl-1.7.html",
+    "ssec-relnotes-1.8": "release-notes/rl-1.8.html",
+    "ssec-relnotes-1.9": "release-notes/rl-1.9.html",
+    "ssec-relnotes-2.0": "release-notes/rl-2.0.html",
+    "ssec-relnotes-2.1": "release-notes/rl-2.1.html",
+    "ssec-relnotes-2.2": "release-notes/rl-2.2.html",
+    "ssec-relnotes-2.3": "release-notes/rl-2.3.html"
+  },
+  "language/values.html": {
+    "simple-values": "#primitives",
+    "lists": "#list",
+    "strings": "#string",
+    "lists": "#list",
+    "attribute-sets": "#attribute-set"
+  }
 };
 
-var isRoot = (document.location.pathname.endsWith('/') || document.location.pathname.endsWith('/index.html')) && path_to_root === '';
-if (isRoot && redirects[document.location.hash]) {
-  document.location.href = path_to_root + redirects[document.location.hash];
+// the following code matches the current page's URL against the set of redirects.
+//
+// it is written to minimize the latency between page load and redirect.
+// therefore we avoid function calls, copying data, and unnecessary loops.
+// IMPORTANT: we use stateful array operations and their order matters!
+//
+// matching URLs is more involved than it should be:
+//
+// 1. `document.location.pathname` can have an arbitrary prefix.
+//
+// 2. `path_to_root` is set by mdBook. it consists only of `../`s and
+//    determines the depth of `<path>` relative to the prefix:
+//
+//          `document.location.pathname`
+//        |------------------------------|
+//        /<prefix>/<path>/[<file>[.html]][#<anchor>]
+//                  |----|
+//              `path_to_root` has same number of path segments
+//
+//    source: https://phaiax.github.io/mdBook/format/theme/index-hbs.html#data
+//
+// 3. the following paths are equivalent:
+//
+//        /foo/bar/
+//        /foo/bar/index.html
+//        /foo/bar/index
+//
+//  4. the following paths are also equivalent:
+//
+//        /foo/bar/baz
+//        /foo/bar/baz.html
+//
+
+let segments = document.location.pathname.split('/');
+
+let file = segments.pop();
+
+// normalize file name
+if (file === '') { file = "index.html"; }
+else if (!file.endsWith('.html')) { file = file + '.html'; }
+
+segments.push(file);
+
+// use `path_to_root` to discern prefix from path.
+const depth = path_to_root.split('/').length;
+
+// remove segments containing prefix. the following works because
+// 1. the original `document.location.pathname` is absolute,
+//    hence first element of `segments` is always empty.
+// 2. last element of splitting `path_to_root` is also always empty.
+// 3. last element of `segments` is the file name.
+//
+// visual example:
+//
+//     '/foo/bar/baz.html'.split('/') -> [ '', 'foo', 'bar', 'baz.html' ]
+//          '../'.split('/')          -> [ '..', '' ]
+//
+// the following operations will then result in
+//
+//     path = 'bar/baz.html'
+//
+segments.splice(0, segments.length - depth);
+const path = segments.join('/');
+
+// anchor starts with the hash character (`#`),
+// but our redirect declarations don't, so we strip it.
+// example:
+//     document.location.hash -> '#foo'
+//     document.location.hash.substring(1) -> 'foo'
+const anchor = document.location.hash.substring(1);
+
+const redirect = redirects[path];
+if (redirect) {
+  const target = redirect[anchor];
+  if (target) {
+    document.location.href = target;
+  }
 }

doc/manual/src/SUMMARY.md.in

@@ -26,21 +26,15 @@
     - [Copying Closures via SSH](package-management/copy-closure.md)
     - [Serving a Nix store via SSH](package-management/ssh-substituter.md)
     - [Serving a Nix store via S3](package-management/s3-substituter.md)
-- [Writing Nix Expressions](expressions/writing-nix-expressions.md)
-  - [A Simple Nix Expression](expressions/simple-expression.md)
-    - [Expression Syntax](expressions/expression-syntax.md)
-    - [Build Script](expressions/build-script.md)
-    - [Arguments and Variables](expressions/arguments-variables.md)
-    - [Building and Testing](expressions/simple-building-testing.md)
-    - [Generic Builder Syntax](expressions/generic-builder.md)
-  - [Writing Nix Expressions](expressions/expression-language.md)
-    - [Values](expressions/language-values.md)
-    - [Language Constructs](expressions/language-constructs.md)
-    - [Operators](expressions/language-operators.md)
-    - [Derivations](expressions/derivations.md)
-      - [Advanced Attributes](expressions/advanced-attributes.md)
-    - [Built-in Constants](expressions/builtin-constants.md)
-    - [Built-in Functions](expressions/builtins.md)
+- [Nix Language](language/index.md)
+  - [Data Types](language/values.md)
+  - [Language Constructs](language/constructs.md)
+    - [String interpolation](language/string-interpolation.md)
+  - [Operators](language/operators.md)
+  - [Derivations](language/derivations.md)
+    - [Advanced Attributes](language/advanced-attributes.md)
+  - [Built-in Constants](language/builtin-constants.md)
+  - [Built-in Functions](language/builtins.md)
 - [Advanced Topics](advanced-topics/advanced-topics.md)
   - [Remote Builds](advanced-topics/distributed-builds.md)
   - [Tuning Cores and Jobs](advanced-topics/cores-vs-jobs.md)
@@ -66,12 +60,15 @@
 @manpages@
   - [Files](command-ref/files.md)
     - [nix.conf](command-ref/conf-file.md)
+- [Architecture](architecture/architecture.md)
 - [Glossary](glossary.md)
 - [Contributing](contributing/contributing.md)
   - [Hacking](contributing/hacking.md)
   - [CLI guideline](contributing/cli-guideline.md)
 - [Release Notes](release-notes/release-notes.md)
-  - [Release X.Y (202?-??-??)](release-notes/rl-next.md)
+  - [Release 2.13 (2023-01-17)](release-notes/rl-2.13.md)
+  - [Release 2.12 (2022-12-06)](release-notes/rl-2.12.md)
+  - [Release 2.11 (2022-08-25)](release-notes/rl-2.11.md)
   - [Release 2.10 (2022-07-11)](release-notes/rl-2.10.md)
   - [Release 2.9 (2022-05-30)](release-notes/rl-2.9.md)
   - [Release 2.8 (2022-04-19)](release-notes/rl-2.8.md)

doc/manual/src/advanced-topics/diff-hook.md

@@ -121,37 +121,3 @@ error:
     are not valid, so checking is not possible
 
 Run the build without `--check`, and then try with `--check` again.
-
-# Automatic and Optionally Enforced Determinism Verification
-
-Automatically verify every build at build time by executing the build
-multiple times.
-
-Setting `repeat` and `enforce-determinism` in your `nix.conf` permits
-the automated verification of every build Nix performs.
-
-The following configuration will run each build three times, and will
-require the build to be deterministic:
-
-    enforce-determinism = true
-    repeat = 2
-
-Setting `enforce-determinism` to false as in the following
-configuration will run the build multiple times, execute the build
-hook, but will allow the build to succeed even if it does not build
-reproducibly:
-
-    enforce-determinism = false
-    repeat = 1
-
-An example output of this configuration:
-
-```console
-$ nix-build ./test.nix -A unstable
-this derivation will be built:
-  /nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv
-building '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' (round 1/2)...
-building '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' (round 2/2)...
-output '/nix/store/6xg356v9gl03hpbbg8gws77n19qanh02-unstable' of '/nix/store/ch6llwpr2h8c3jmnf3f2ghkhx59aa97f-unstable.drv' differs from '/nix/store/6xg356v9gl03hpbbg8gws77n19qanh02-unstable.check' from previous round
-/nix/store/6xg356v9gl03hpbbg8gws77n19qanh02-unstable
-```

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

@@ -12,14 +12,14 @@ machine is accessible via SSH and that it has Nix installed. You can
 test whether connecting to the remote Nix instance works, e.g.
 
 ```console
-$ nix ping-store --store ssh://mac
+$ nix store ping --store ssh://mac
 ```
 
 will try to connect to the machine named `mac`. It is possible to
 specify an SSH identity file as part of the remote store URI, e.g.
 
 ```console
-$ nix ping-store --store ssh://mac?ssh-key=/home/alice/my-key
+$ nix store ping --store ssh://mac?ssh-key=/home/alice/my-key
 ```
 
 Since builds should be non-interactive, the key should not have a

doc/manual/src/advanced-topics/post-build-hook.md

@@ -33,12 +33,17 @@ distribute the public key for verifying the authenticity of the paths.
 example-nix-cache-1:1/cKDz3QCCOmwcztD2eV6Coggp6rqc9DGjWv7C0G+rM=
 ```
 
-Then, add the public key and the cache URL to your `nix.conf`'s
-`trusted-public-keys` and `substituters` options:
+Then update [`nix.conf`](../command-ref/conf-file.md) on any machine that will access the cache.
+Add the cache URL to [`substituters`](../command-ref/conf-file.md#conf-substituters) and the public key to [`trusted-public-keys`](../command-ref/conf-file.md#conf-trusted-public-keys):
 
     substituters = https://cache.nixos.org/ s3://example-nix-cache
     trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= example-nix-cache-1:1/cKDz3QCCOmwcztD2eV6Coggp6rqc9DGjWv7C0G+rM=
 
+Machines that build for the cache must sign derivations using the private key.
+On those machines, add the path to the key file to the [`secret-key-files`](../command-ref/conf-file.md#conf-secret-key-files) field in their [`nix.conf`](../command-ref/conf-file.md):
+
+    secret-key-files = /etc/nix/key.private
+
 We will restart the Nix daemon in a later step.
 
 # Implementing the build hook
@@ -52,14 +57,12 @@ set -eu
 set -f # disable globbing
 export IFS=' '
 
-echo "Signing paths" $OUT_PATHS
-nix store sign --key-file /etc/nix/key.private $OUT_PATHS
 echo "Uploading paths" $OUT_PATHS
-exec nix copy --to 's3://example-nix-cache' $OUT_PATHS
+exec nix copy --to "s3://example-nix-cache" $OUT_PATHS
 ```
 
 > **Note**
-> 
+>
 > The `$OUT_PATHS` variable is a space-separated list of Nix store
 > paths. In this case, we expect and want the shell to perform word
 > splitting to make each output path its own argument to `nix

doc/manual/src/architecture/architecture.md

@@ -0,0 +1,115 @@
+# Architecture
+
+This chapter describes how Nix works.
+It should help users understand why Nix behaves as it does, and it should help developers understand how to modify Nix and how to write similar tools.
+
+## Overview
+
+Nix consists of [hierarchical layers].
+
+[hierarchical layers]: https://en.m.wikipedia.org/wiki/Multitier_architecture#Layers
+
+The following [concept map] shows its main components (rectangles), the objects they operate on (rounded rectangles), and their interactions (connecting phrases):
+
+[concept map]: https://en.m.wikipedia.org/wiki/Concept_map
+
+```
+
+   .----------------.
+   | Nix expression |----------.
+   '----------------'          |
+           |              passed to
+           |                   |
++----------|-------------------|--------------------------------+
+| Nix      |                   V                                |
+|          |      +-------------------------+                   |
+|          |      | commmand line interface |------.            |
+|          |      +-------------------------+      |            |
+|          |                   |                   |            |
+|    evaluated by            calls              manages         |
+|          |                   |                   |            |
+|          |                   V                   |            |
+|          |         +--------------------+        |            |
+|          '-------->| language evaluator |        |            |
+|                    +--------------------+        |            |
+|                              |                   |            |
+|                           produces               |            |
+|                              |                   V            |
+| +----------------------------|------------------------------+ |
+| | store                      |                              | |
+| |            referenced by   V       builds                 | |
+| | .-------------.      .------------.      .--------------. | |
+| | | build input |----->| build plan |----->| build result | | |
+| | '-------------'      '------------'      '--------------' | |
+| +-------------------------------------------------|---------+ |
++---------------------------------------------------|-----------+
+                                                    |
+                                              represented as
+                                                    |
+                                                    V
+                                            .---------------.
+                                            |     file      |
+                                            '---------------'
+```
+
+At the top is the [command line interface](../command-ref/command-ref.md) that drives the underlying layers.
+
+The [Nix language](../language/index.md) evaluator transforms Nix expressions into self-contained *build plans*, which are used to derive *build results* from referenced *build inputs*.
+
+The command line interface and Nix expressions are what users deal with most.
+
+> **Note**
+> The Nix language itself does not have a notion of *packages* or *configurations*.
+> As far as we are concerned here, the inputs and results of a build plan are just data.
+
+Underlying the command line interface and the Nix language evaluator is the [Nix store](../glossary.md#gloss-store), a mechanism to keep track of build plans, data, and references between them.
+It can also execute build plans to produce new data, which are made available to the operating system as files.
+
+A build plan itself is a series of *build tasks*, together with their build inputs.
+
+> **Important**
+> A build task in Nix is called [derivation](../glossary.md#gloss-derivation).
+
+Each build task has a special build input executed as *build instructions* in order to perform the build.
+The result of a build task can be input to another build task.
+
+The following [data flow diagram] shows a build plan for illustration.
+Build inputs used as instructions to a build task are marked accordingly:
+
+[data flow diagram]: https://en.m.wikipedia.org/wiki/Data-flow_diagram
+
+```
++--------------------------------------------------------------------+
+| build plan                                                         |
+|                                                                    |
+| .-------------.                                                    |
+| | build input |---------.                                          |
+| '-------------'         |                                          |
+|                    instructions                                    |
+|                         |                                          |
+|                         v                                          |
+| .-------------.    .----------.                                    |
+| | build input |-->( build task )-------.                           |
+| '-------------'    '----------'        |                           |
+|                                  instructions                      |
+|                                        |                           |
+|                                        v                           |
+| .-------------.                  .----------.     .--------------. |
+| | build input |---------.       ( build task )--->| build result | |
+| '-------------'         |        '----------'     '--------------' |
+|                    instructions        ^                           |
+|                         |              |                           |
+|                         v              |                           |
+| .-------------.    .----------.        |                           |
+| | build input |-->( build task )-------'                           |
+| '-------------'    '----------'                                    |
+|                         ^                                          |
+|                         |                                          |
+|                         |                                          |
+| .-------------.         |                                          |
+| | build input |---------'                                          |
+| '-------------'                                                    |
+|                                                                    |
++--------------------------------------------------------------------+
+```
+

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

@@ -7,42 +7,11 @@ Most Nix commands interpret the following environment variables:
     `nix-shell`. It can have the values `pure` or `impure`.
 
   - [`NIX_PATH`]{#env-NIX_PATH}\
-    A colon-separated list of directories used to look up Nix
-    expressions enclosed in angle brackets (i.e., `<path>`). For
-    instance, the value
-
-        /home/eelco/Dev:/etc/nixos
-
-    will cause Nix to look for paths relative to `/home/eelco/Dev` and
-    `/etc/nixos`, in this order. It is also possible to match paths
-    against a prefix. For example, the value
-
-        nixpkgs=/home/eelco/Dev/nixpkgs-branch:/etc/nixos
-
-    will cause Nix to search for `<nixpkgs/path>` in
-    `/home/eelco/Dev/nixpkgs-branch/path` and `/etc/nixos/nixpkgs/path`.
-
-    If a path in the Nix search path starts with `http://` or
-    `https://`, it is interpreted as the URL of a tarball that will be
-    downloaded and unpacked to a temporary location. The tarball must
-    consist of a single top-level directory. For example, setting
-    `NIX_PATH` to
-
-        nixpkgs=https://github.com/NixOS/nixpkgs/archive/master.tar.gz
-
-    tells Nix to download and use the current contents of the
-    `master` branch in the `nixpkgs` repository.
-
-    The URLs of the tarballs from the official nixos.org channels (see
-    [the manual for `nix-channel`](nix-channel.md)) can be abbreviated
-    as `channel:<channel-name>`.  For instance, the following two
-    values of `NIX_PATH` are equivalent:
-
-        nixpkgs=channel:nixos-21.05
-        nixpkgs=https://nixos.org/channels/nixos-21.05/nixexprs.tar.xz
-
-    The Nix search path can also be extended using the `-I` option to
-    many Nix commands, which takes precedence over `NIX_PATH`.
+    A colon-separated list of directories used to look up the location of Nix
+    expressions using [paths](../language/values.md#type-path)
+    enclosed in angle brackets (i.e., `<path>`),
+    e.g. `/home/eelco/Dev:/etc/nixos`. It can be extended using the
+    [`-I` option](./opt-common.md#opt-I).
 
   - [`NIX_IGNORE_SYMLINK_STORE`]{#env-NIX_IGNORE_SYMLINK_STORE}\
     Normally, the Nix store directory (typically `/nix/store`) is not

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

@@ -37,10 +37,12 @@ directory containing at least a file named `default.nix`.
 
 `nix-build` is essentially a wrapper around
 [`nix-instantiate`](nix-instantiate.md) (to translate a high-level Nix
-expression to a low-level store derivation) and [`nix-store
+expression to a low-level [store derivation]) and [`nix-store
 --realise`](nix-store.md#operation---realise) (to build the store
 derivation).
 
+[store derivation]: ../glossary.md#gloss-store-derivation
+
 > **Warning**
 >
 > The result of the build is automatically registered as a root of the
@@ -53,16 +55,18 @@ All options not listed here are passed to `nix-store
 --realise`, except for `--arg` and `--attr` / `-A` which are passed to
 `nix-instantiate`.
 
-  - [`--no-out-link`]{#opt-no-out-link}\
+  - <span id="opt-no-out-link">[`--no-out-link`](#opt-no-out-link)<span>
+
     Do not create a symlink to the output path. Note that as a result
     the output does not become a root of the garbage collector, and so
-    might be deleted by `nix-store
-                    --gc`.
+    might be deleted by `nix-store --gc`.
+
+  - <span id="opt-dry-run">[`--dry-run`](#opt-dry-run)</span>
 
-  - [`--dry-run`]{#opt-dry-run}\
     Show what store paths would be built or downloaded.
 
-  - [`--out-link`]{#opt-out-link} / `-o` *outlink*\
+  - <span id="opt-out-link">[`--out-link`](#opt-out-link)</span> / `-o` *outlink*
+
     Change the name of the symlink to the output path created from
     `result` to *outlink*.
 

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

@@ -30,8 +30,8 @@ Since `nix-copy-closure` calls `ssh`, you may be asked to type in the
 appropriate password or passphrase.  In fact, you may be asked _twice_
 because `nix-copy-closure` currently connects twice to the remote
 machine, first to get the set of paths missing on the target machine,
-and second to send the dump of those paths.  If this bothers you, use
-`ssh-agent`.
+and second to send the dump of those paths.  When using public key
+authentication, you can avoid typing the passphrase with `ssh-agent`.
 
 # Options
 
@@ -47,7 +47,9 @@ and second to send the dump of those paths.  If this bothers you, use
     Enable compression of the SSH connection.
 
   - `--include-outputs`\
-    Also copy the outputs of store derivations included in the closure.
+    Also copy the outputs of [store derivation]s included in the closure.
+
+    [store derivation]: ../glossary.md#gloss-store-derivation
 
   - `--use-substitutes` / `-s`\
     Attempt to download missing paths on the target machine using Nix’s

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

@@ -8,6 +8,6 @@
 
 # Description
 
-The Nix daemon is necessary in multi-user Nix installations. It performs
-build actions and other operations on the Nix store on behalf of
+The Nix daemon is necessary in multi-user Nix installations. It runs
+build tasks and other operations on the Nix store on behalf of
 unprivileged users.

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

@@ -198,17 +198,19 @@ a number of possible ways:
     another.
 
   - If `--from-expression` is given, *args* are Nix
-    [functions](../expressions/language-constructs.md#functions)
+    [functions](../language/constructs.md#functions)
     that are called with the active Nix expression as their single
     argument. The derivations returned by those function calls are
     installed. This allows derivations to be specified in an
     unambiguous way, which is necessary if there are multiple
     derivations with the same name.
 
-  - If *args* are store derivations, then these are
+  - If *args* are [store derivation]s, then these are
     [realised](nix-store.md#operation---realise), and the resulting output paths
     are installed.
 
+    [store derivation]: ../glossary.md#gloss-store-derivation
+
   - If *args* are store paths that are not store derivations, then these
     are [realised](nix-store.md#operation---realise) and installed.
 
@@ -280,7 +282,7 @@ To copy the store path with symbolic name `gcc` from another profile:
 $ nix-env -i --from-profile /nix/var/nix/profiles/foo gcc
 ```
 
-To install a specific store derivation (typically created by
+To install a specific [store derivation] (typically created by
 `nix-instantiate`):
 
 ```console
@@ -665,7 +667,7 @@ derivation is shown unless `--no-name` is specified.
     Print the `system` attribute of the derivation.
 
   - `--drv-path`\
-    Print the path of the store derivation.
+    Print the path of the [store derivation].
 
   - `--out-path`\
     Print the output path of the derivation.

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

@@ -17,13 +17,14 @@
 
 # Description
 
-The command `nix-instantiate` generates [store
-derivations](../glossary.md) from (high-level) Nix expressions. It
-evaluates the Nix expressions in each of *files* (which defaults to
+The command `nix-instantiate` produces [store derivation]s from (high-level) Nix expressions.
+It evaluates the Nix expressions in each of *files* (which defaults to
 *./default.nix*). Each top-level expression should evaluate to a
 derivation, a list of derivations, or a set of derivations. The paths
 of the resulting store derivations are printed on standard output.
 
+[store derivation]: ../glossary.md#gloss-store-derivation
+
 If *files* is the character `-`, then a Nix expression will be read from
 standard input.
 
@@ -51,7 +52,7 @@ standard input.
   - `--strict`\
     When used with `--eval`, recursively evaluate list elements and
     attributes. Normally, such sub-expressions are left unevaluated
-    (since the Nix expression language is lazy).
+    (since the Nix language is lazy).
 
     > **Warning**
     >
@@ -66,7 +67,7 @@ standard input.
     When used with `--eval`, print the resulting value as an XML
     representation of the abstract syntax tree rather than as an ATerm.
     The schema is the same as that used by the [`toXML`
-    built-in](../expressions/builtins.md).
+    built-in](../language/builtins.md).
 
   - `--read-write-mode`\
     When used with `--eval`, perform evaluation in read/write mode so
@@ -79,8 +80,7 @@ standard input.
 
 # Examples
 
-Instantiating store derivations from a Nix expression, and building them
-using `nix-store`:
+Instantiate [store derivation]s from a Nix expression, and build them using `nix-store`:
 
 ```console
 $ nix-instantiate test.nix (instantiate)

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

@@ -22,7 +22,8 @@ This section lists the options that are common to all operations. These
 options are allowed for every subcommand, though they may not always
 have an effect.
 
-  - [`--add-root`]{#opt-add-root} *path*\
+  - <span id="opt-add-root">[`--add-root`](#opt-add-root)</span> *path*
+
     Causes the result of a realisation (`--realise` and
     `--force-realise`) to be registered as a root of the garbage
     collector. *path* will be created as a symlink to the resulting
@@ -71,7 +72,7 @@ paths. Realisation is a somewhat overloaded term:
     outputs are already valid, in which case we are done
     immediately. Otherwise, there may be [substitutes](../glossary.md)
     that produce the outputs (e.g., by downloading them). Finally, the
-    outputs can be produced by performing the build action described
+    outputs can be produced by running the build task described
     by the derivation.
 
   - If the store path is not a derivation, realisation ensures that the
@@ -104,10 +105,6 @@ The following flags are available:
     previous build, the new output path is left in
     `/nix/store/name.check.`
 
-    See also the `build-repeat` configuration option, which repeats a
-    derivation a number of times and prevents its outputs from being
-    registered as “valid” in the Nix store unless they are identical.
-
 Special exit codes:
 
   - `100`\
@@ -121,7 +118,7 @@ Special exit codes:
   - `102`\
     Hash mismatch, the build output was rejected because it does not
     match the [`outputHash` attribute of the
-    derivation](../expressions/advanced-attributes.md).
+    derivation](../language/advanced-attributes.md).
 
   - `104`\
     Not deterministic, the build succeeded in check mode but the
@@ -140,8 +137,10 @@ or.
 
 ## Examples
 
-This operation is typically used to build store derivations produced by
-[`nix-instantiate`](nix-instantiate.md):
+This operation is typically used to build [store derivation]s produced by
+[`nix-instantiate`](./nix-instantiate.md):
+
+[store derivation]: ../glossary.md#gloss-store-derivation
 
 ```console
 $ nix-store -r $(nix-instantiate ./test.nix)
@@ -156,6 +155,12 @@ To test whether a previously-built derivation is deterministic:
 $ nix-build '<nixpkgs>' -A hello --check -K
 ```
 
+Use [`--read-log`](#operation---read-log) to show the stderr and stdout of a build:
+
+```console
+$ nix-store --read-log $(nix-instantiate ./test.nix)
+```
+
 # Operation `--serve`
 
 ## Synopsis
@@ -301,7 +306,7 @@ symlink.
 ## Common query options
 
   - `--use-output`; `-u`\
-    For each argument to the query that is a store derivation, apply the
+    For each argument to the query that is a [store derivation], apply the
     query to the output path of the derivation instead.
 
   - `--force-realise`; `-f`\
@@ -321,7 +326,7 @@ symlink.
     This query has one option:
 
       - `--include-outputs`
-        Also include the existing output paths of store derivations,
+        Also include the existing output paths of [store derivation]s,
         and their closures.
 
     This query can be used to implement various kinds of deployment. A
@@ -375,12 +380,12 @@ symlink.
     Prints the references graph of the store paths *paths* in the
     [GraphML](http://graphml.graphdrawing.org/) file format. This can be
     used to visualise dependency graphs. To obtain a build-time
-    dependency graph, apply this to a store derivation. To obtain a
+    dependency graph, apply this to a [store derivation]. To obtain a
     runtime dependency graph, apply it to an output path.
 
   - `--binding` *name*; `-b` *name*\
     Prints the value of the attribute *name* (i.e., environment
-    variable) of the store derivations *paths*. It is an error for a
+    variable) of the [store derivation]s *paths*. It is an error for a
     derivation to not have the specified attribute.
 
   - `--hash`\

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

@@ -145,7 +145,7 @@ Most Nix commands accept the following command-line options:
     expression evaluator will automatically try to call functions that
     it encounters. It can automatically call functions for which every
     argument has a [default
-    value](../expressions/language-constructs.md#functions) (e.g.,
+    value](../language/constructs.md#functions) (e.g.,
     `{ argName ?  defaultValue }: ...`). With `--arg`, you can also
     call functions that have arguments without a default value (or
     override a default value). That is, if the evaluator encounters a
@@ -164,7 +164,7 @@ Most Nix commands accept the following command-line options:
 
     So if you call this Nix expression (e.g., when you do `nix-env -iA
     pkgname`), the function will be called automatically using the
-    value [`builtins.currentSystem`](../expressions/builtins.md) for
+    value [`builtins.currentSystem`](../language/builtins.md) for
     the `system` argument. You can override this using `--arg`, e.g.,
     `nix-env -iA pkgname --arg system \"i686-freebsd\"`. (Note that
     since the argument is a Nix string literal, you have to escape the

doc/manual/src/contributing/hacking.md

@@ -42,7 +42,7 @@ $ nix develop
 ```
 
 To get a shell with a different compilation environment (e.g. stdenv,
-gccStdenv, clangStdenv, clang11Stdenv):
+gccStdenv, clangStdenv, clang11Stdenv, ccacheStdenv):
 
 ```console
 $ nix-shell -A devShells.x86_64-linux.clang11StdenvPackages
@@ -54,6 +54,9 @@ or if you have a flake-enabled nix:
 $ nix develop .#clang11StdenvPackages
 ```
 
+Note: you can use `ccacheStdenv` to drastically improve rebuild
+time. By default, ccache keeps artifacts in `~/.cache/ccache/`.
+
 To build Nix itself in this shell:
 
 ```console
@@ -83,9 +86,7 @@ by:
 $ nix develop
 ```
 
-## Testing
-
-Nix comes with three different flavors of tests: unit, functional and integration.
+## Running tests
 
 ### Unit-tests
 
@@ -98,8 +99,79 @@ You can run the whole testsuite with `make check`, or the tests for a specific c
 ### Functional tests
 
 The functional tests reside under the `tests` directory and are listed in `tests/local.mk`.
-The whole testsuite can be run with `make install && make installcheck`.
-Individual tests can be run with `make tests/{testName}.sh.test`.
+Each test is a bash script.
+
+The whole test suite can be run with:
+
+```shell-session
+$ make install && make installcheck
+ran test tests/foo.sh... [PASS]
+ran test tests/bar.sh... [PASS]
+...
+```
+
+Individual tests can be run with `make`:
+
+```shell-session
+$ make tests/${testName}.sh.test
+ran test tests/${testName}.sh... [PASS]
+```
+
+or without `make`:
+
+```shell-session
+$ ./mk/run-test.sh tests/${testName}.sh
+ran test tests/${testName}.sh... [PASS]
+```
+
+To see the complete output, one can also run:
+
+```shell-session
+$ ./mk/debug-test.sh tests/${testName}.sh
++ foo
+output from foo
++ bar
+output from bar
+...
+```
+
+The test script will then be traced with `set -x` and the output displayed as it happens, regardless of whether the test succeeds or fails.
+
+#### Debugging failing functional tests
+
+When a functional test fails, it usually does so somewhere in the middle of the script.
+
+To figure out what's wrong, it is convenient to run the test regularly up to the failing `nix` command, and then run that command with a debugger like GDB.
+
+For example, if the script looks like:
+
+```bash
+foo
+nix blah blub
+bar
+```
+edit it like so:
+
+```diff
+ foo
+-nix blah blub
++gdb --args nix blah blub
+ bar
+```
+
+Then, running the test with `./mk/debug-test.sh` will drop you into GDB once the script reaches that point:
+
+```shell-session
+$ ./mk/debug-test.sh tests/${testName}.sh
+...
++ gdb blash blub
+GNU gdb (GDB) 12.1
+...
+(gdb)
+```
+
+One can debug the Nix invocation in all the usual ways.
+For example, enter `run` to start the Nix invocation.
 
 ### Integration tests
 
@@ -108,3 +180,105 @@ These tests include everything that needs to interact with external services or
 Because these tests are expensive and require more than what the standard github-actions setup provides, they only run on the master branch (on <https://hydra.nixos.org/jobset/nix/master>).
 
 You can run them manually with `nix build .#hydraJobs.tests.{testName}` or `nix-build -A hydraJobs.tests.{testName}`
+
+### Installer tests
+
+After a one-time setup, the Nix repository's GitHub Actions continuous integration (CI) workflow can test the installer each time you push to a branch.
+
+Creating a Cachix cache for your installer tests and adding its authorization token to GitHub enables [two installer-specific jobs in the CI workflow](https://github.com/NixOS/nix/blob/88a45d6149c0e304f6eb2efcc2d7a4d0d569f8af/.github/workflows/ci.yml#L50-L91):
+
+- The `installer` job generates installers for the platforms below and uploads them to your Cachix cache:
+  - `x86_64-linux`
+  - `armv6l-linux`
+  - `armv7l-linux`
+  - `x86_64-darwin`
+
+- The `installer_test` job (which runs on `ubuntu-latest` and `macos-latest`) will try to install Nix with the cached installer and run a trivial Nix command.
+
+#### One-time setup
+
+1. Have a GitHub account with a fork of the [Nix repository](https://github.com/NixOS/nix).
+2. At cachix.org:
+    - Create or log in to an account.
+    - Create a Cachix cache using the format `<github-username>-nix-install-tests`.
+    - Navigate to the new cache > Settings > Auth Tokens.
+    - Generate a new Cachix auth token and copy the generated value.
+3. At github.com:
+    - Navigate to your Nix fork > Settings > Secrets > Actions > New repository secret.
+    - Name the secret `CACHIX_AUTH_TOKEN`.
+    - Paste the copied value of the Cachix cache auth token.
+
+#### Using the CI-generated installer for manual testing
+
+After the CI run completes, you can check the output to extract the installer URL:
+1. Click into the detailed view of the CI run.
+2. Click into any `installer_test` run (the URL you're here to extract will be the same in all of them).
+3. Click into the `Run cachix/install-nix-action@v...` step and click the detail triangle next to the first log line (it will also be `Run cachix/install-nix-action@v...`)
+4. Copy the value of `install_url`
+5. To generate an install command, plug this `install_url` and your GitHub username into this template:
+
+    ```console
+    sh <(curl -L <install_url>) --tarball-url-prefix https://<github-username>-nix-install-tests.cachix.org/serve
+    ```
+
+<!-- #### Manually generating test installers
+
+There's obviously a manual way to do this, and it's still the only way for
+platforms that lack GA runners.
+
+I did do this back in Fall 2020 (before the GA approach encouraged here). I'll
+sketch what I recall in case it encourages someone to fill in detail, but: I
+didn't know what I was doing at the time and had to fumble/ask around a lot--
+so I don't want to uphold any of it as "right". It may have been dumb or
+the _hard_ way from the getgo. Fundamentals may have changed since.
+
+Here's the build command I used to do this on and for x86_64-darwin:
+nix build --out-link /tmp/foo ".#checks.x86_64-darwin.binaryTarball"
+
+I used the stable out-link to make it easier to script the next steps:
+link=$(readlink /tmp/foo)
+cp $link/*-darwin.tar.xz ~/somewheres
+
+I've lost the last steps and am just going from memory:
+
+From here, I think I had to extract and modify the `install` script to point
+it at this tarball (which I scped to my own site, but it might make more sense
+to just share them locally). I extracted this script once and then just
+search/replaced in it for each new build.
+
+The installer now supports a `--tarball-url-prefix` flag which _may_ have
+solved this need?
+-->
+
+### Checking links in the manual
+
+The build checks for broken internal links.
+This happens late in the process, so `nix build` is not suitable for iterating.
+To build the manual incrementally, run:
+
+```console
+make html -j $NIX_BUILD_CORES
+```
+
+In order to reflect changes to the [Makefile], clear all generated files before re-building:
+
+[Makefile]: https://github.com/NixOS/nix/blob/master/doc/manual/local.mk
+
+```console
+rm $(git ls-files doc/manual/ -o | grep -F '.md') && rmdir doc/manual/src/command-ref/new-cli && make html -j $NIX_BUILD_CORES
+```
+
+[`mdbook-linkcheck`] does not implement checking [URI fragments] yet.
+
+[`mdbook-linkcheck`]: https://github.com/Michael-F-Bryan/mdbook-linkcheck
+[URI fragments]: https://en.m.wikipedia.org/wiki/URI_fragment
+
+#### `@docroot@` variable
+
+`@docroot@` provides a base path for links that occur in reusable snippets or other documentation that doesn't have a base path of its own.
+
+If a broken link occurs in a snippet that was inserted into multiple generated files in different directories, use `@docroot@` to reference the `doc/manual/src` directory.
+
+If the `@docroot@` literal appears in an error message from the `mdbook-linkcheck` tool, the `@docroot@` replacement needs to be applied to the generated source file that mentions it.
+See existing `@docroot@` logic in the [Makefile].
+Regular markdown files used for the manual have a base path of their own and they can use relative paths instead of `@docroot@`.

doc/manual/src/expressions/arguments-variables.md

@@ -1,80 +0,0 @@
-# Arguments and Variables
-
-The [Nix expression for GNU Hello](expression-syntax.md) is a
-function; it is missing some arguments that have to be filled in
-somewhere. In the Nix Packages collection this is done in the file
-`pkgs/top-level/all-packages.nix`, where all Nix expressions for
-packages are imported and called with the appropriate arguments. Here
-are some fragments of `all-packages.nix`, with annotations of what
-they mean:
-
-```nix
-...
-
-rec { ①
-
-  hello = import ../applications/misc/hello/ex-1 ② { ③
-    inherit fetchurl stdenv perl;
-  };
-
-  perl = import ../development/interpreters/perl { ④
-    inherit fetchurl stdenv;
-  };
-
-  fetchurl = import ../build-support/fetchurl {
-    inherit stdenv; ...
-  };
-
-  stdenv = ...;
-
-}
-```
-
-1.  This file defines a set of attributes, all of which are concrete
-    derivations (i.e., not functions). In fact, we define a *mutually
-    recursive* set of attributes. That is, the attributes can refer to
-    each other. This is precisely what we want since we want to “plug”
-    the various packages into each other.
-
-2.  Here we *import* the Nix expression for GNU Hello. The import
-    operation just loads and returns the specified Nix expression. In
-    fact, we could just have put the contents of the Nix expression
-    for GNU Hello in `all-packages.nix` at this point. That would be
-    completely equivalent, but it would make `all-packages.nix` rather
-    bulky.
-    
-    Note that we refer to `../applications/misc/hello/ex-1`, not
-    `../applications/misc/hello/ex-1/default.nix`. When you try to
-    import a directory, Nix automatically appends `/default.nix` to the
-    file name.
-
-3.  This is where the actual composition takes place. Here we *call* the
-    function imported from `../applications/misc/hello/ex-1` with a set
-    containing the things that the function expects, namely `fetchurl`,
-    `stdenv`, and `perl`. We use inherit again to use the attributes
-    defined in the surrounding scope (we could also have written
-    `fetchurl = fetchurl;`, etc.).
-    
-    The result of this function call is an actual derivation that can be
-    built by Nix (since when we fill in the arguments of the function,
-    what we get is its body, which is the call to `stdenv.mkDerivation`
-    in the [Nix expression for GNU Hello](expression-syntax.md)).
-    
-    > **Note**
-    > 
-    > Nixpkgs has a convenience function `callPackage` that imports and
-    > calls a function, filling in any missing arguments by passing the
-    > corresponding attribute from the Nixpkgs set, like this:
-    > 
-    > ```nix
-    > hello = callPackage ../applications/misc/hello/ex-1 { };
-    > ```
-    > 
-    > If necessary, you can set or override arguments:
-    > 
-    > ```nix
-    > hello = callPackage ../applications/misc/hello/ex-1 { stdenv = myStdenv; };
-    > ```
-
-4.  Likewise, we have to instantiate Perl, `fetchurl`, and the standard
-    environment.

doc/manual/src/expressions/build-script.md

@@ -1,70 +0,0 @@
-# Build Script
-
-Here is the builder referenced from Hello's Nix expression (stored in
-`pkgs/applications/misc/hello/ex-1/builder.sh`):
-
-```bash
-source $stdenv/setup ①
-
-PATH=$perl/bin:$PATH ②
-
-tar xvfz $src ③
-cd hello-*
-./configure --prefix=$out ④
-make ⑤
-make install
-```
-
-The builder can actually be made a lot shorter by using the *generic
-builder* functions provided by `stdenv`, but here we write out the build
-steps to elucidate what a builder does. It performs the following steps:
-
-1.  When Nix runs a builder, it initially completely clears the
-    environment (except for the attributes declared in the derivation).
-    This is done to prevent undeclared inputs from being used in the
-    build process. If for example the `PATH` contained `/usr/bin`, then
-    you might accidentally use `/usr/bin/gcc`.
-    
-    So the first step is to set up the environment. This is done by
-    calling the `setup` script of the standard environment. The
-    environment variable `stdenv` points to the location of the
-    standard environment being used. (It wasn't specified explicitly
-    as an attribute in Hello's Nix expression, but `mkDerivation` adds
-    it automatically.)
-
-2.  Since Hello needs Perl, we have to make sure that Perl is in the
-    `PATH`. The `perl` environment variable points to the location of
-    the Perl package (since it was passed in as an attribute to the
-    derivation), so `$perl/bin` is the directory containing the Perl
-    interpreter.
-
-3.  Now we have to unpack the sources. The `src` attribute was bound to
-    the result of fetching the Hello source tarball from the network, so
-    the `src` environment variable points to the location in the Nix
-    store to which the tarball was downloaded. After unpacking, we `cd`
-    to the resulting source directory.
-    
-    The whole build is performed in a temporary directory created in
-    `/tmp`, by the way. This directory is removed after the builder
-    finishes, so there is no need to clean up the sources afterwards.
-    Also, the temporary directory is always newly created, so you don't
-    have to worry about files from previous builds interfering with the
-    current build.
-
-4.  GNU Hello is a typical Autoconf-based package, so we first have to
-    run its `configure` script. In Nix every package is stored in a
-    separate location in the Nix store, for instance
-    `/nix/store/9a54ba97fb71b65fda531012d0443ce2-hello-2.1.1`. Nix
-    computes this path by cryptographically hashing all attributes of
-    the derivation. The path is passed to the builder through the `out`
-    environment variable. So here we give `configure` the parameter
-    `--prefix=$out` to cause Hello to be installed in the expected
-    location.
-
-5.  Finally we build Hello (`make`) and install it into the location
-    specified by `out` (`make install`).
-
-If you are wondering about the absence of error checking on the result
-of various commands called in the builder: this is because the shell
-script is evaluated with Bash's `-e` option, which causes the script to
-be aborted if any command fails without an error check.

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

@@ -1,12 +0,0 @@
-# Nix Expression Language
-
-The Nix expression language is a pure, lazy, functional language. Purity
-means that operations in the language don't have side-effects (for
-instance, there is no variable assignment). Laziness means that
-arguments to functions are evaluated only when they are needed.
-Functional means that functions are “normal” values that can be passed
-around and manipulated in interesting ways. The language is not a
-full-featured, general purpose language. Its main job is to describe
-packages, compositions of packages, and the variability within packages.
-
-This section presents the various features of the language.

doc/manual/src/expressions/expression-syntax.md

@@ -1,93 +0,0 @@
-# Expression Syntax
-
-Here is a Nix expression for GNU Hello:
-
-```nix
-{ stdenv, fetchurl, perl }: ①
-
-stdenv.mkDerivation { ②
-  name = "hello-2.1.1"; ③
-  builder = ./builder.sh; ④
-  src = fetchurl { ⑤
-    url = "ftp://ftp.nluug.nl/pub/gnu/hello/hello-2.1.1.tar.gz";
-    sha256 = "1md7jsfd8pa45z73bz1kszpp01yw6x5ljkjk2hx7wl800any6465";
-  };
-  inherit perl; ⑥
-}
-```
-
-This file is actually already in the Nix Packages collection in
-`pkgs/applications/misc/hello/ex-1/default.nix`. It is customary to
-place each package in a separate directory and call the single Nix
-expression in that directory `default.nix`. The file has the following
-elements (referenced from the figure by number):
-
-1.  This states that the expression is a *function* that expects to be
-    called with three arguments: `stdenv`, `fetchurl`, and `perl`. They
-    are needed to build Hello, but we don't know how to build them here;
-    that's why they are function arguments. `stdenv` is a package that
-    is used by almost all Nix Packages; it provides a
-    “standard” environment consisting of the things you would expect
-    in a basic Unix environment: a C/C++ compiler (GCC, to be precise),
-    the Bash shell, fundamental Unix tools such as `cp`, `grep`, `tar`,
-    etc. `fetchurl` is a function that downloads files. `perl` is the
-    Perl interpreter.
-    
-    Nix functions generally have the form `{ x, y, ..., z }: e` where
-    `x`, `y`, etc. are the names of the expected arguments, and where
-    *e* is the body of the function. So here, the entire remainder of
-    the file is the body of the function; when given the required
-    arguments, the body should describe how to build an instance of
-    the Hello package.
-
-2.  So we have to build a package. Building something from other stuff
-    is called a *derivation* in Nix (as opposed to sources, which are
-    built by humans instead of computers). We perform a derivation by
-    calling `stdenv.mkDerivation`. `mkDerivation` is a function
-    provided by `stdenv` that builds a package from a set of
-    *attributes*. A set is just a list of key/value pairs where each
-    key is a string and each value is an arbitrary Nix
-    expression. They take the general form `{ name1 = expr1; ...
-    nameN = exprN; }`.
-
-3.  The attribute `name` specifies the symbolic name and version of
-    the package. Nix doesn't really care about these things, but they
-    are used by for instance `nix-env -q` to show a “human-readable”
-    name for packages. This attribute is required by `mkDerivation`.
-
-4.  The attribute `builder` specifies the builder. This attribute can
-    sometimes be omitted, in which case `mkDerivation` will fill in a
-    default builder (which does a `configure; make; make install`, in
-    essence). Hello is sufficiently simple that the default builder
-    would suffice, but in this case, we will show an actual builder
-    for educational purposes. The value `./builder.sh` refers to the
-    shell script shown in the [next section](build-script.md),
-    discussed below.
-
-5.  The builder has to know what the sources of the package are. Here,
-    the attribute `src` is bound to the result of a call to the
-    `fetchurl` function. Given a URL and a SHA-256 hash of the expected
-    contents of the file at that URL, this function builds a derivation
-    that downloads the file and checks its hash. So the sources are a
-    dependency that like all other dependencies is built before Hello
-    itself is built.
-    
-    Instead of `src` any other name could have been used, and in fact
-    there can be any number of sources (bound to different attributes).
-    However, `src` is customary, and it's also expected by the default
-    builder (which we don't use in this example).
-
-6.  Since the derivation requires Perl, we have to pass the value of the
-    `perl` function argument to the builder. All attributes in the set
-    are actually passed as environment variables to the builder, so
-    declaring an attribute
-
-    ```nix
-    perl = perl;
-    ```
-    
-    will do the trick: it binds an attribute `perl` to the function
-    argument which also happens to be called `perl`. However, it looks a
-    bit silly, so there is a shorter syntax. The `inherit` keyword
-    causes the specified attributes to be bound to whatever variables
-    with the same name happen to be in scope.

doc/manual/src/expressions/generic-builder.md

@@ -1,66 +0,0 @@
-# Generic Builder Syntax
-
-Recall that the [build script for GNU Hello](build-script.md) looked
-something like this:
-
-```bash
-PATH=$perl/bin:$PATH
-tar xvfz $src
-cd hello-*
-./configure --prefix=$out
-make
-make install
-```
-
-The builders for almost all Unix packages look like this — set up some
-environment variables, unpack the sources, configure, build, and
-install. For this reason the standard environment provides some Bash
-functions that automate the build process. Here is what a builder using
-the generic build facilities looks like:
-
-```bash
-buildInputs="$perl" ①
-
-source $stdenv/setup ②
-
-genericBuild ③
-```
-
-Here is what each line means:
-
-1.  The `buildInputs` variable tells `setup` to use the indicated
-    packages as “inputs”. This means that if a package provides a `bin`
-    subdirectory, it's added to `PATH`; if it has a `include`
-    subdirectory, it's added to GCC's header search path; and so on.
-    (This is implemented in a modular way: `setup` tries to source the
-    file `pkg/nix-support/setup-hook` of all dependencies. These “setup
-    hooks” can then set up whatever environment variables they want; for
-    instance, the setup hook for Perl sets the `PERL5LIB` environment
-    variable to contain the `lib/site_perl` directories of all inputs.)
-
-2.  The function `genericBuild` is defined in the file `$stdenv/setup`.
-
-3.  The final step calls the shell function `genericBuild`, which
-    performs the steps that were done explicitly in the previous build
-    script. The generic builder is smart enough to figure out whether
-    to unpack the sources using `gzip`, `bzip2`, etc.  It can be
-    customised in many ways; see the Nixpkgs manual for details.
-
-Discerning readers will note that the `buildInputs` could just as well
-have been set in the Nix expression, like this:
-
-```nix
-  buildInputs = [ perl ];
-```
-
-The `perl` attribute can then be removed, and the builder becomes even
-shorter:
-
-```bash
-source $stdenv/setup
-genericBuild
-```
-
-In fact, `mkDerivation` provides a default builder that looks exactly
-like that, so it is actually possible to omit the builder for Hello
-entirely.

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

@@ -1,28 +0,0 @@
-# Operators
-
-The table below lists the operators in the Nix expression language, in
-order of precedence (from strongest to weakest binding).
-
-| Name                     | Syntax                              | Associativity | Description                                                                                                                                                                                                                   | Precedence |
-| ------------------------ | ----------------------------------- | ------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------- |
-| Select                   | *e* `.` *attrpath* \[ `or` *def* \] | none          | Select attribute denoted by the attribute path *attrpath* from set *e*. (An attribute path is a dot-separated list of attribute names.) If the attribute doesn’t exist, return *def* if provided, otherwise abort evaluation. | 1          |
-| Application              | *e1* *e2*                           | left          | Call function *e1* with argument *e2*.                                                                                                                                                                                        | 2          |
-| Arithmetic Negation      | `-` *e*                             | none          | Arithmetic negation.                                                                                                                                                                                                          | 3          |
-| Has Attribute            | *e* `?` *attrpath*                  | none          | Test whether set *e* contains the attribute denoted by *attrpath*; return `true` or `false`.                                                                                                                                  | 4          |
-| List Concatenation       | *e1* `++` *e2*                      | right         | List concatenation.                                                                                                                                                                                                           | 5          |
-| Multiplication           | *e1* `*` *e2*,                      | left          | Arithmetic multiplication.                                                                                                                                                                                                    | 6          |
-| Division                 | *e1* `/` *e2*                       | left          | Arithmetic division.                                                                                                                                                                                                          | 6          |
-| Addition                 | *e1* `+` *e2*                       | left          | Arithmetic addition.                                                                                                                                                                                                          | 7          |
-| Subtraction              | *e1* `-` *e2*                       | left          | Arithmetic subtraction.                                                                                                                                                                                                       | 7          |
-| String Concatenation     | *string1* `+` *string2*             | left          | String concatenation.                                                                                                                                                                                                         | 7          |
-| Not                      | `!` *e*                             | none          | Boolean negation.                                                                                                                                                                                                             | 8          |
-| Update                   | *e1* `//` *e2*                      | right         | Return a set consisting of the attributes in *e1* and *e2* (with the latter taking precedence over the former in case of equally named attributes).                                                                           | 9          |
-| Less Than                | *e1* `<` *e2*,                      | none          | Arithmetic/lexicographic comparison.                                                                                                                                                                                                        | 10         |
-| Less Than or Equal To    | *e1* `<=` *e2*                      | none          | Arithmetic/lexicographic comparison.                                                                                                                                                                                                        | 10         |
-| Greater Than             | *e1* `>` *e2*                       | none          | Arithmetic/lexicographic comparison.                                                                                                                                                                                                        | 10         |
-| Greater Than or Equal To | *e1* `>=` *e2*                      | none          | Arithmetic/lexicographic comparison.                                                                                                                                                                                                        | 10         |
-| Equality                 | *e1* `==` *e2*                      | none          | Equality.                                                                                                                                                                                                                     | 11         |
-| Inequality               | *e1* `!=` *e2*                      | none          | Inequality.                                                                                                                                                                                                                   | 11         |
-| Logical AND              | *e1* `&&` *e2*                      | left          | Logical AND.                                                                                                                                                                                                                  | 12         |
-| Logical OR               | *e1* <code>&#124;&#124;</code> *e2* | left          | Logical OR.                                                                                                                                                                                                                   | 13         |
-| Logical Implication      | *e1* `->` *e2*                      | none          | Logical implication (equivalent to <code>!e1 &#124;&#124; e2</code>).                                                                                                                                                                            | 14         |

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

@@ -1,251 +0,0 @@
-# Values
-
-## Simple Values
-
-Nix has the following basic data types:
-
-  - *Strings* can be written in three ways.
-    
-    The most common way is to enclose the string between double quotes,
-    e.g., `"foo bar"`. Strings can span multiple lines. The special
-    characters `"` and `\` and the character sequence `${` must be
-    escaped by prefixing them with a backslash (`\`). Newlines, carriage
-    returns and tabs can be written as `\n`, `\r` and `\t`,
-    respectively.
-    
-    You can include the result of an expression into a string by
-    enclosing it in `${...}`, a feature known as *antiquotation*. The
-    enclosed expression must evaluate to something that can be coerced
-    into a string (meaning that it must be a string, a path, or a
-    derivation). For instance, rather than writing
-    
-    ```nix
-    "--with-freetype2-library=" + freetype + "/lib"
-    ```
-    
-    (where `freetype` is a derivation), you can instead write the more
-    natural
-    
-    ```nix
-    "--with-freetype2-library=${freetype}/lib"
-    ```
-    
-    The latter is automatically translated to the former. A more
-    complicated example (from the Nix expression for
-    [Qt](http://www.trolltech.com/products/qt)):
-    
-    ```nix
-    configureFlags = "
-      -system-zlib -system-libpng -system-libjpeg
-      ${if openglSupport then "-dlopen-opengl
-        -L${mesa}/lib -I${mesa}/include
-        -L${libXmu}/lib -I${libXmu}/include" else ""}
-      ${if threadSupport then "-thread" else "-no-thread"}
-    ";
-    ```
-    
-    Note that Nix expressions and strings can be arbitrarily nested; in
-    this case the outer string contains various antiquotations that
-    themselves contain strings (e.g., `"-thread"`), some of which in
-    turn contain expressions (e.g., `${mesa}`).
-    
-    The second way to write string literals is as an *indented string*,
-    which is enclosed between pairs of *double single-quotes*, like so:
-    
-    ```nix
-    ''
-      This is the first line.
-      This is the second line.
-        This is the third line.
-    ''
-    ```
-    
-    This kind of string literal intelligently strips indentation from
-    the start of each line. To be precise, it strips from each line a
-    number of spaces equal to the minimal indentation of the string as a
-    whole (disregarding the indentation of empty lines). For instance,
-    the first and second line are indented two spaces, while the third
-    line is indented four spaces. Thus, two spaces are stripped from
-    each line, so the resulting string is
-    
-    ```nix
-    "This is the first line.\nThis is the second line.\n  This is the third line.\n"
-    ```
-    
-    Note that the whitespace and newline following the opening `''` is
-    ignored if there is no non-whitespace text on the initial line.
-    
-    Antiquotation (`${expr}`) is supported in indented strings.
-    
-    Since `${` and `''` have special meaning in indented strings, you
-    need a way to quote them. `$` can be escaped by prefixing it with
-    `''` (that is, two single quotes), i.e., `''$`. `''` can be escaped
-    by prefixing it with `'`, i.e., `'''`. `$` removes any special
-    meaning from the following `$`. Linefeed, carriage-return and tab
-    characters can be written as `''\n`, `''\r`, `''\t`, and `''\`
-    escapes any other character.
-    
-    Indented strings are primarily useful in that they allow multi-line
-    string literals to follow the indentation of the enclosing Nix
-    expression, and that less escaping is typically necessary for
-    strings representing languages such as shell scripts and
-    configuration files because `''` is much less common than `"`.
-    Example:
-    
-    ```nix
-    stdenv.mkDerivation {
-      ...
-      postInstall =
-        ''
-          mkdir $out/bin $out/etc
-          cp foo $out/bin
-          echo "Hello World" > $out/etc/foo.conf
-          ${if enableBar then "cp bar $out/bin" else ""}
-        '';
-      ...
-    }
-    ```
-    
-    Finally, as a convenience, *URIs* as defined in appendix B of
-    [RFC 2396](http://www.ietf.org/rfc/rfc2396.txt) can be written *as
-    is*, without quotes. For instance, the string
-    `"http://example.org/foo.tar.bz2"` can also be written as
-    `http://example.org/foo.tar.bz2`.
-
-  - Numbers, which can be *integers* (like `123`) or *floating point*
-    (like `123.43` or `.27e13`).
-    
-    Numbers are type-compatible: pure integer operations will always
-    return integers, whereas any operation involving at least one
-    floating point number will have a floating point number as a result.
-
-  - *Paths*, e.g., `/bin/sh` or `./builder.sh`. A path must contain at
-    least one slash to be recognised as such. For instance, `builder.sh`
-    is not a path: it's parsed as an expression that selects the
-    attribute `sh` from the variable `builder`. If the file name is
-    relative, i.e., if it does not begin with a slash, it is made
-    absolute at parse time relative to the directory of the Nix
-    expression that contained it. For instance, if a Nix expression in
-    `/foo/bar/bla.nix` refers to `../xyzzy/fnord.nix`, the absolute path
-    is `/foo/xyzzy/fnord.nix`.
-    
-    If the first component of a path is a `~`, it is interpreted as if
-    the rest of the path were relative to the user's home directory.
-    e.g. `~/foo` would be equivalent to `/home/edolstra/foo` for a user
-    whose home directory is `/home/edolstra`.
-    
-    Paths can also be specified between angle brackets, e.g.
-    `<nixpkgs>`. This means that the directories listed in the
-    environment variable `NIX_PATH` will be searched for the given file
-    or directory name.
-
-    Antiquotation is supported in any paths except those in angle brackets.
-    `./${foo}-${bar}.nix` is a more convenient way of writing 
-    `./. + "/" + foo + "-" + bar + ".nix"` or `./. + "/${foo}-${bar}.nix"`. At
-    least one slash must appear *before* any antiquotations for this to be
-    recognized as a path. `a.${foo}/b.${bar}` is a syntactically valid division
-    operation. `./a.${foo}/b.${bar}` is a path.
-
-  - *Booleans* with values `true` and `false`.
-
-  - The null value, denoted as `null`.
-
-## Lists
-
-Lists are formed by enclosing a whitespace-separated list of values
-between square brackets. For example,
-
-```nix
-[ 123 ./foo.nix "abc" (f { x = y; }) ]
-```
-
-defines a list of four elements, the last being the result of a call to
-the function `f`. Note that function calls have to be enclosed in
-parentheses. If they had been omitted, e.g.,
-
-```nix
-[ 123 ./foo.nix "abc" f { x = y; } ]
-```
-
-the result would be a list of five elements, the fourth one being a
-function and the fifth being a set.
-
-Note that lists are only lazy in values, and they are strict in length.
-
-## Sets
-
-Sets are really the core of the language, since ultimately the Nix
-language is all about creating derivations, which are really just sets
-of attributes to be passed to build scripts.
-
-Sets are just a list of name/value pairs (called *attributes*) enclosed
-in curly brackets, where each value is an arbitrary expression
-terminated by a semicolon. For example:
-
-```nix
-{ x = 123;
-  text = "Hello";
-  y = f { bla = 456; };
-}
-```
-
-This defines a set with attributes named `x`, `text`, `y`. The order of
-the attributes is irrelevant. An attribute name may only occur once.
-
-Attributes can be selected from a set using the `.` operator. For
-instance,
-
-```nix
-{ a = "Foo"; b = "Bar"; }.a
-```
-
-evaluates to `"Foo"`. It is possible to provide a default value in an
-attribute selection using the `or` keyword. For example,
-
-```nix
-{ a = "Foo"; b = "Bar"; }.c or "Xyzzy"
-```
-
-will evaluate to `"Xyzzy"` because there is no `c` attribute in the set.
-
-You can use arbitrary double-quoted strings as attribute names:
-
-```nix
-{ "foo ${bar}" = 123; "nix-1.0" = 456; }."foo ${bar}"
-```
-
-This will evaluate to `123` (Assuming `bar` is antiquotable). In the
-case where an attribute name is just a single antiquotation, the quotes
-can be dropped:
-
-```nix
-{ foo = 123; }.${bar} or 456
-```
-
-This will evaluate to `123` if `bar` evaluates to `"foo"` when coerced
-to a string and `456` otherwise (again assuming `bar` is antiquotable).
-
-In the special case where an attribute name inside of a set declaration
-evaluates to `null` (which is normally an error, as `null` is not
-antiquotable), that attribute is simply not added to the set:
-
-```nix
-{ ${if foo then "bar" else null} = true; }
-```
-
-This will evaluate to `{}` if `foo` evaluates to `false`.
-
-A set that has a `__functor` attribute whose value is callable (i.e. is
-itself a function or a set with a `__functor` attribute whose value is
-callable) can be applied as if it were a function, with the set itself
-passed in first , e.g.,
-
-```nix
-let add = { __functor = self: x: x + self.x; };
-    inc = add // { x = 1; };
-in inc 1
-```
-
-evaluates to `2`. This can be used to attach metadata to a function
-without the caller needing to treat it specially, or to implement a form
-of object-oriented programming, for example.

doc/manual/src/expressions/simple-building-testing.md

@@ -1,61 +0,0 @@
-# Building and Testing
-
-You can now try to build Hello. Of course, you could do `nix-env -f . -iA
-hello`, but you may not want to install a possibly broken package just
-yet. The best way to test the package is by using the command
-`nix-build`, which builds a Nix expression and creates a symlink named
-`result` in the current directory:
-
-```console
-$ nix-build -A hello
-building path `/nix/store/632d2b22514d...-hello-2.1.1'
-hello-2.1.1/
-hello-2.1.1/intl/
-hello-2.1.1/intl/ChangeLog
-...
-
-$ ls -l result
-lrwxrwxrwx ... 2006-09-29 10:43 result -> /nix/store/632d2b22514d...-hello-2.1.1
-
-$ ./result/bin/hello
-Hello, world!
-```
-
-The `-A` option selects the `hello` attribute. This is faster than
-using the symbolic package name specified by the `name` attribute
-(which also happens to be `hello`) and is unambiguous (there can be
-multiple packages with the symbolic name `hello`, but there can be
-only one attribute in a set named `hello`).
-
-`nix-build` registers the `./result` symlink as a garbage collection
-root, so unless and until you delete the `./result` symlink, the output
-of the build will be safely kept on your system. You can use
-`nix-build`’s `-o` switch to give the symlink another name.
-
-Nix has transactional semantics. Once a build finishes successfully, Nix
-makes a note of this in its database: it registers that the path denoted
-by `out` is now “valid”. If you try to build the derivation again, Nix
-will see that the path is already valid and finish immediately. If a
-build fails, either because it returns a non-zero exit code, because Nix
-or the builder are killed, or because the machine crashes, then the
-output paths will not be registered as valid. If you try to build the
-derivation again, Nix will remove the output paths if they exist (e.g.,
-because the builder died half-way through `make
-install`) and try again. Note that there is no “negative caching”: Nix
-doesn't remember that a build failed, and so a failed build can always
-be repeated. This is because Nix cannot distinguish between permanent
-failures (e.g., a compiler error due to a syntax error in the source)
-and transient failures (e.g., a disk full condition).
-
-Nix also performs locking. If you run multiple Nix builds
-simultaneously, and they try to build the same derivation, the first Nix
-instance that gets there will perform the build, while the others block
-(or perform other derivations if available) until the build finishes:
-
-```console
-$ nix-build -A hello
-waiting for lock on `/nix/store/0h5b7hp8d4hqfrw8igvx97x1xawrjnac-hello-2.1.1x'
-```
-
-So it is always safe to run multiple instances of Nix in parallel (which
-isn’t the case with, say, `make`).

doc/manual/src/expressions/simple-expression.md

@@ -1,23 +0,0 @@
-# A Simple Nix Expression
-
-This section shows how to add and test the [GNU Hello
-package](http://www.gnu.org/software/hello/hello.html) to the Nix
-Packages collection. Hello is a program that prints out the text “Hello,
-world\!”.
-
-To add a package to the Nix Packages collection, you generally need to
-do three things:
-
-1.  Write a Nix expression for the package. This is a file that
-    describes all the inputs involved in building the package, such as
-    dependencies, sources, and so on.
-
-2.  Write a *builder*. This is a shell script that builds the package
-    from the inputs. (In fact, it can be written in any language, but
-    typically it's a `bash` shell script.)
-
-3.  Add the package to the file `pkgs/top-level/all-packages.nix`. The
-    Nix expression written in the first step is a *function*; it
-    requires other packages in order to build it. In this step you put
-    it all together, i.e., you call the function with the right
-    arguments to build the actual package.

doc/manual/src/expressions/writing-nix-expressions.md

@@ -1,12 +0,0 @@
-This chapter shows you how to write Nix expressions, which instruct Nix
-how to build packages. It starts with a simple example (a Nix expression
-for GNU Hello), and then moves on to a more in-depth look at the Nix
-expression language.
-
-> **Note**
-> 
-> This chapter is mostly about the Nix expression language. For more
-> extensive information on adding packages to the Nix Packages
-> collection (such as functions in the standard environment and coding
-> conventions), please consult [its
-> manual](http://nixos.org/nixpkgs/manual/).

doc/manual/src/glossary.md

@@ -1,26 +1,93 @@
 # Glossary
 
   - [derivation]{#gloss-derivation}\
-    A description of a build action. The result of a derivation is a
+    A description of a build task. The result of a derivation is a
     store object. Derivations are typically specified in Nix expressions
-    using the [`derivation` primitive](expressions/derivations.md). These are
+    using the [`derivation` primitive](./language/derivations.md). These are
     translated into low-level *store derivations* (implicitly by
     `nix-env` and `nix-build`, or explicitly by `nix-instantiate`).
 
+    [derivation]: #gloss-derivation
+
+  - [store derivation]{#gloss-store-derivation}\
+    A [derivation] represented as a `.drv` file in the [store].
+    It has a [store path], like any [store object].
+
+    Example: `/nix/store/g946hcz4c8mdvq2g8vxx42z51qb71rvp-git-2.38.1.drv`
+
+    See [`nix show-derivation`](./command-ref/new-cli/nix3-show-derivation.md) (experimental) for displaying the contents of store derivations.
+
+    [store derivation]: #gloss-store-derivation
+
+  - [content-addressed derivation]{#gloss-content-addressed-derivation}\
+    A derivation which has the
+    [`__contentAddressed`](./language/advanced-attributes.md#adv-attr-__contentAddressed)
+    attribute set to `true`.
+
+  - [fixed-output derivation]{#gloss-fixed-output-derivation}\
+    A derivation which includes the
+    [`outputHash`](./language/advanced-attributes.md#adv-attr-outputHash) attribute.
+
   - [store]{#gloss-store}\
     The location in the file system where store objects live. Typically
     `/nix/store`.
 
+    From   the  perspective   of   the  location   where  Nix   is
+    invoked, the  Nix store can be  referred to
+    as a "_local_" or a "_remote_" one:
+
+    + A *local  store* exists  on the filesystem of
+      the machine where Nix is  invoked. You can use other
+      local stores  by passing  the `--store` flag  to the
+      `nix` command.  Local stores can be used for building derivations.
+
+    + A  *remote store*  exists  anywhere  other than  the
+      local  filesystem. One  example is  the `/nix/store`
+      directory on another machine,  accessed via `ssh` or
+      served by the `nix-serve` Perl script.
+
+    [store]: #gloss-store
+
+  - [chroot store]{#gloss-chroot-store}\
+    A local store whose canonical path is anything other than `/nix/store`.
+
+  - [binary cache]{#gloss-binary-cache}\
+    A *binary cache* is a Nix store which uses a different format: its
+    metadata and signatures are kept in `.narinfo` files rather than in a
+    Nix database.  This different format simplifies serving store objects
+    over the network, but cannot host builds.  Examples of binary caches
+    include S3 buckets and the [NixOS binary
+    cache](https://cache.nixos.org).
+
   - [store path]{#gloss-store-path}\
-    The location in the file system of a store object, i.e., an
+    The location of a [store object] in the file system, i.e., an
     immediate child of the Nix store directory.
 
+    Example: `/nix/store/a040m110amc4h71lds2jmr8qrkj2jhxd-git-2.38.1`
+
+    [store path]: #gloss-store-path
+
   - [store object]{#gloss-store-object}\
     A file that is an immediate child of the Nix store directory. These
     can be regular files, but also entire directory trees. Store objects
     can be sources (objects copied from outside of the store),
-    derivation outputs (objects produced by running a build action), or
-    derivations (files describing a build action).
+    derivation outputs (objects produced by running a build task), or
+    derivations (files describing a build task).
+
+    [store object]: #gloss-store-object
+
+  - [input-addressed store object]{#gloss-input-addressed-store-object}\
+    A store object produced by building a
+    non-[content-addressed](#gloss-content-addressed-derivation),
+    non-[fixed-output](#gloss-fixed-output-derivation)
+    derivation.
+
+  - [output-addressed store object]{#gloss-output-addressed-store-object}\
+    A store object whose store path hashes its content.  This
+    includes derivations, the outputs of
+    [content-addressed derivations](#gloss-content-addressed-derivation),
+    and the outputs of
+    [fixed-output derivations](#gloss-fixed-output-derivation).
 
   - [substitute]{#gloss-substitute}\
     A substitute is a command invocation stored in the Nix database that
@@ -29,6 +96,11 @@
     store object by downloading a pre-built version of the store object
     from some server.
 
+  - [substituter]{#gloss-substituter}\
+    A *substituter* is an additional store from which Nix will
+    copy store objects it doesn't have.  For details, see the
+    [`substituters` option](./command-ref/conf-file.md#conf-substituters).
+
   - [purity]{#gloss-purity}\
     The assumption that equal Nix derivations when run always produce
     the same output. This cannot be guaranteed in general (e.g., a
@@ -72,7 +144,9 @@
     references `R` then `R` is also in the closure of `P`.
 
   - [output path]{#gloss-output-path}\
-    A store path produced by a derivation.
+    A [store path] produced by a [derivation].
+
+    [output path]: #gloss-output-path
 
   - [deriver]{#gloss-deriver}\
     The deriver of an *output path* is the store
@@ -87,7 +161,7 @@
     An automatically generated store object that consists of a set of
     symlinks to “active” applications, i.e., other store paths. These
     are generated automatically by
-    [`nix-env`](command-ref/nix-env.md). See *profiles*.
+    [`nix-env`](./command-ref/nix-env.md). See *profiles*.
 
   - [profile]{#gloss-profile}\
     A symlink to the current *user environment* of a user, e.g.,
@@ -98,7 +172,18 @@
     store. It can contain regular files, directories and symbolic
     links.  NARs are generated and unpacked using `nix-store --dump`
     and `nix-store --restore`.
+
   - [`∅`]{#gloss-emtpy-set}\
     The empty set symbol. In the context of profile history, this denotes a package is not present in a particular version of the profile.
+
   - [`ε`]{#gloss-epsilon}\
     The epsilon symbol. In the context of a package, this means the version is empty. More precisely, the derivation does not have a version attribute.
+
+  - [string interpolation]{#gloss-string-interpolation}\
+    Expanding expressions enclosed in `${ }` within a [string], [path], or [attribute name].
+
+    See [String interpolation](./language/string-interpolation.md) for details.
+
+    [string]: ./language/values.md#type-string
+    [path]: ./language/values.md#type-path
+    [attribute name]: ./language/values.md#attribute-set

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

@@ -13,7 +13,7 @@ for your platform:
 - multi-user on macOS
 
   > **Notes on read-only filesystem root in macOS 10.15 Catalina +**
-  > 
+  >
   > - It took some time to support this cleanly. You may see posts,
   >   examples, and tutorials using obsolete workarounds.
   > - Supporting it cleanly made macOS installs too complex to qualify
@@ -31,8 +31,8 @@ $ sh <(curl -L https://nixos.org/nix/install) --no-daemon
 ```
 
 This will perform a single-user installation of Nix, meaning that `/nix`
-is owned by the invoking user. You should run this under your usual user
-account, *not* as root. The script will invoke `sudo` to create `/nix`
+is owned by the invoking user. You can run this under your usual user
+account or root. The script will invoke `sudo` to create `/nix`
 if it doesn’t already exist. If you don’t have `sudo`, you should
 manually create `/nix` first as root, e.g.:
 
@@ -71,11 +71,11 @@ $ sh <(curl -L https://nixos.org/nix/install) --daemon
 
 The multi-user installation of Nix will create build users between the
 user IDs 30001 and 30032, and a group with the group ID 30000. You
-should run this under your usual user account, *not* as root. The script
+can run this under your usual user account or root. The script
 will invoke `sudo` as needed.
 
 > **Note**
-> 
+>
 > If you need Nix to use a different group ID or user ID set, you will
 > have to download the tarball manually and [edit the install
 > script](#installing-from-a-binary-tarball).
@@ -88,19 +88,51 @@ extension. The installer will also create `/etc/profile.d/nix.sh`.
 
 ### Linux
 
-```console
-sudo rm -rf /etc/profile/nix.sh /etc/nix /nix ~root/.nix-profile ~root/.nix-defexpr ~root/.nix-channels ~/.nix-profile ~/.nix-defexpr ~/.nix-channels
+If you are on Linux with systemd:
 
-# If you are on Linux with systemd, you will need to run:
-sudo systemctl stop nix-daemon.socket
-sudo systemctl stop nix-daemon.service
-sudo systemctl disable nix-daemon.socket
-sudo systemctl disable nix-daemon.service
-sudo systemctl daemon-reload
+1. Remove the Nix daemon service:
+
+   ```console
+   sudo systemctl stop nix-daemon.service
+   sudo systemctl disable nix-daemon.socket nix-daemon.service
+   sudo systemctl daemon-reload
+   ```
+
+1. Remove systemd service files:
+
+   ```console
+   sudo rm /etc/systemd/system/nix-daemon.service /etc/systemd/system/nix-daemon.socket
+   ```
+
+1. The installer script uses systemd-tmpfiles to create the socket directory.
+    You may also want to remove the configuration for that:
+
+   ```console
+   sudo rm /etc/tmpfiles.d/nix-daemon.conf
+   ```
+
+Remove files created by Nix:
+
+```console
+sudo rm -rf /nix /etc/nix /etc/profile/nix.sh ~root/.nix-profile ~root/.nix-defexpr ~root/.nix-channels ~/.nix-profile ~/.nix-defexpr ~/.nix-channels
 ```
 
-There may also be references to Nix in `/etc/profile`, `/etc/bashrc`,
-and `/etc/zshrc` which you may remove.
+Remove build users and their group:
+
+```console
+for i in $(seq 1 32); do
+  sudo userdel nixbld$i
+done
+sudo groupdel nixbld
+```
+
+There may also be references to Nix in
+
+- `/etc/profile`
+- `/etc/bashrc`
+- `/etc/zshrc`
+
+which you may remove.
 
 ### macOS
 
@@ -148,7 +180,8 @@ and `/etc/zshrc` which you may remove.
    This will remove all the build users that no longer serve a purpose.
 
 4. Edit fstab using `sudo vifs` to remove the line mounting the Nix Store
-   volume on `/nix`, which looks like this,
+   volume on `/nix`, which looks like
+   `UUID=<uuid> /nix apfs rw,noauto,nobrowse,suid,owners` or
    `LABEL=Nix\040Store /nix apfs rw,nobrowse`. This will prevent automatic
    mounting of the Nix Store volume.
 
@@ -167,7 +200,7 @@ and `/etc/zshrc` which you may remove.
    removed next.
 
 7. Remove the Nix Store volume:
-   
+
    ```console
    sudo diskutil apfs deleteVolume /nix
    ```
@@ -175,8 +208,20 @@ and `/etc/zshrc` which you may remove.
    This will remove the Nix Store volume and everything that was added to the
    store.
 
+   If the output indicates that the command couldn't remove the volume, you should
+   make sure you don't have an _unmounted_ Nix Store volume. Look for a
+   "Nix Store" volume in the output of the following command:
+
+   ```console
+   diskutil list
+   ```
+
+   If you _do_ see a "Nix Store" volume, delete it by re-running the diskutil
+   deleteVolume command, but replace `/nix` with the store volume's `diskXsY`
+   identifier.
+
 > **Note**
-> 
+>
 > After you complete the steps here, you will still have an empty `/nix`
 > directory. This is an expected sign of a successful uninstall. The empty
 > `/nix` directory will disappear the next time you reboot.
@@ -191,8 +236,7 @@ and `/etc/zshrc` which you may remove.
 <!-- Note: anchors above to catch permalinks to old explanations -->
 
 We believe we have ironed out how to cleanly support the read-only root
-on modern macOS. New installs will do this automatically, and you can
-also re-run a new installer to convert your existing setup.
+on modern macOS. New installs will do this automatically.
 
 This section previously detailed the situation, options, and trade-offs,
 but it now only outlines what the installer does. You don't need to know

doc/manual/src/introduction.md

@@ -104,7 +104,7 @@ a currently running program.
 
 Packages are built from _Nix expressions_, which is a simple
 functional language.  A Nix expression describes everything that goes
-into a package build action (a “derivation”): other packages, sources,
+into a package build task (a “derivation”): other packages, sources,
 the build script, environment variables for the build script, etc.
 Nix tries very hard to ensure that Nix expressions are
 _deterministic_: building a Nix expression twice should yield the same

doc/manual/src/language/derivations.md

@@ -1,7 +1,7 @@
 # Derivations
 
 The most important built-in function is `derivation`, which is used to
-describe a single derivation (a build action). It takes as input a set,
+describe a single derivation (a build task). It takes as input a set,
 the attributes of which specify the inputs of the build.
 
   - There must be an attribute named [`system`]{#attr-system} whose value must be a

doc/manual/src/language/index.md

@@ -0,0 +1,581 @@
+# Nix Language
+
+The Nix language is
+
+- *domain-specific*
+
+  It only exists for the Nix package manager:
+  to describe packages and configurations as well as their variants and compositions.
+  It is not intended for general purpose use.
+
+- *declarative*
+
+  There is no notion of executing sequential steps.
+  Dependencies between operations are established only through data.
+
+- *pure*
+
+  Values cannot change during computation.
+  Functions always produce the same output if their input does not change.
+
+- *functional*
+
+  Functions are like any other value.
+  Functions can be assigned to names, taken as arguments, or returned by functions.
+
+- *lazy*
+
+  Expressions are only evaluated when their value is needed.
+
+- *dynamically typed*
+
+  Type errors are only detected when expressions are evaluated.
+
+# Overview
+
+This is an incomplete overview of language features, by example.
+
+<table>
+ <tr>
+  <th>
+   Example
+  </th>
+  <th>
+   Description
+  </th>
+ </tr>
+ <tr>
+  <td>
+
+
+   *Basic values*
+
+
+  </td>
+  <td>
+
+
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `"hello world"`
+
+  </td>
+  <td>
+
+   A string
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   ```
+   ''
+     multi
+      line
+       string
+   ''
+   ```
+
+  </td>
+  <td>
+
+   A multi-line string. Strips common prefixed whitespace. Evaluates to `"multi\n line\n  string"`.
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `"hello ${ { a = "world" }.a }"`
+
+   `"1 2 ${toString 3}"`
+
+   `"${pkgs.bash}/bin/sh"`
+
+  </td>
+  <td>
+
+   String interpolation (expands to `"hello world"`, `"1 2 3"`, `"/nix/store/<hash>-bash-<version>/bin/sh"`)
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `true`, `false`
+
+  </td>
+  <td>
+
+   Booleans
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `null`
+
+  </td>
+  <td>
+
+   Null value
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `123`
+
+  </td>
+  <td>
+
+   An integer
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `3.141`
+
+  </td>
+  <td>
+
+   A floating point number
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `/etc`
+
+  </td>
+  <td>
+
+   An absolute path
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `./foo.png`
+
+  </td>
+  <td>
+
+   A path relative to the file containing this Nix expression
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `~/.config`
+
+  </td>
+  <td>
+
+   A home path. Evaluates to the `"<user's home directory>/.config"`.
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   <nixpkgs>
+
+  </td>
+  <td>
+
+   Search path. Value determined by [`$NIX_PATH` environment variable](../command-ref/env-common.md#env-NIX_PATH).
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   *Compound values*
+
+  </td>
+  <td>
+
+
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `{ x = 1; y = 2; }`
+
+  </td>
+  <td>
+
+   A set with attributes named `x` and `y`
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `{ foo.bar = 1; }`
+
+  </td>
+  <td>
+
+   A nested set, equivalent to `{ foo = { bar = 1; }; }`
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `rec { x = "foo"; y = x + "bar"; }`
+
+  </td>
+  <td>
+
+   A recursive set, equivalent to `{ x = "foo"; y = "foobar"; }`
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `[ "foo" "bar" "baz" ]`
+
+   `[ 1 2 3 ]`
+
+   `[ (f 1) { a = 1; b = 2; } [ "c" ] ]`
+
+  </td>
+  <td>
+
+   Lists with three elements.
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   *Operators*
+
+  </td>
+  <td>
+
+
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `"foo" + "bar"`
+
+  </td>
+  <td>
+
+   String concatenation
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `1 + 2`
+
+  </td>
+  <td>
+
+   Integer addition
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `"foo" == "f" + "oo"`
+
+  </td>
+  <td>
+
+   Equality test (evaluates to `true`)
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `"foo" != "bar"`
+
+  </td>
+  <td>
+
+   Inequality test (evaluates to `true`)
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `!true`
+
+  </td>
+  <td>
+
+   Boolean negation
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `{ x = 1; y = 2; }.x`
+
+  </td>
+  <td>
+
+   Attribute selection (evaluates to `1`)
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `{ x = 1; y = 2; }.z or 3`
+
+  </td>
+  <td>
+
+   Attribute selection with default (evaluates to `3`)
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `{ x = 1; y = 2; } // { z = 3; }`
+
+  </td>
+  <td>
+
+   Merge two sets (attributes in the right-hand set taking precedence)
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   *Control structures*
+
+  </td>
+  <td>
+
+
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `if 1 + 1 == 2 then "yes!" else "no!"`
+
+  </td>
+  <td>
+
+   Conditional expression
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `assert 1 + 1 == 2; "yes!"`
+
+  </td>
+  <td>
+
+   Assertion check (evaluates to `"yes!"`).
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `let x = "foo"; y = "bar"; in x + y`
+
+  </td>
+  <td>
+
+   Variable definition
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `with builtins; head [ 1 2 3 ]`
+
+  </td>
+  <td>
+
+   Add all attributes from the given set to the scope (evaluates to `1`)
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   *Functions (lambdas)*
+
+  </td>
+  <td>
+
+
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `x: x + 1`
+
+  </td>
+  <td>
+
+   A function that expects an integer and returns it increased by 1
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `x: y: x + y`
+
+  </td>
+  <td>
+
+   Curried function, equivalent to `x: (y: x + y)`. Can be used like a function that takes two arguments and returns their sum.
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `(x: x + 1) 100`
+
+  </td>
+  <td>
+
+   A function call (evaluates to 101)
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `let inc = x: x + 1; in inc (inc (inc 100))`
+
+  </td>
+  <td>
+
+   A function bound to a variable and subsequently called by name (evaluates to 103)
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `{ x, y }: x + y`
+
+  </td>
+  <td>
+
+   A function that expects a set with required attributes `x` and `y` and concatenates them
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `{ x, y ? "bar" }: x + y`
+
+  </td>
+  <td>
+
+   A function that expects a set with required attribute `x` and optional `y`, using `"bar"` as default value for `y`
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `{ x, y, ... }: x + y`
+
+  </td>
+  <td>
+
+   A function that expects a set with required attributes `x` and `y` and ignores any other attributes
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `{ x, y } @ args: x + y`
+
+   `args @ { x, y }: x + y`
+
+  </td>
+  <td>
+
+   A function that expects a set with required attributes `x` and `y`, and binds the whole set to `args`
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   *Built-in functions*
+
+  </td>
+  <td>
+
+
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `import ./foo.nix`
+
+  </td>
+  <td>
+
+   Load and return Nix expression in given file
+
+  </td>
+ </tr>
+ <tr>
+  <td>
+
+   `map (x: x + x) [ 1 2 3 ]`
+
+  </td>
+  <td>
+
+   Apply a function to every element of a list (evaluates to `[ 2 4 6 ]`)
+
+  </td>
+ </tr>
+</table>

doc/manual/src/language/operators.md

@@ -0,0 +1,167 @@
+# Operators
+
+| Name                                   | Syntax                                     | Associativity | Precedence |
+|----------------------------------------|--------------------------------------------|---------------|------------|
+| [Attribute selection]                  | *attrset* `.` *attrpath* \[ `or` *expr* \] | none          | 1          |
+| Function application                   | *func* *expr*                              | left          | 2          |
+| [Arithmetic negation][arithmetic]      | `-` *number*                               | none          | 3          |
+| [Has attribute]                        | *attrset* `?` *attrpath*                   | none          | 4          |
+| List concatenation                     | *list* `++` *list*                         | right         | 5          |
+| [Multiplication][arithmetic]           | *number* `*` *number*                      | left          | 6          |
+| [Division][arithmetic]                 | *number* `/` *number*                      | left          | 6          |
+| [Subtraction][arithmetic]              | *number* `-` *number*                      | left          | 7          |
+| [Addition][arithmetic]                 | *number* `+` *number*                      | left          | 7          |
+| [String concatenation]                 | *string* `+` *string*                      | left          | 7          |
+| [Path concatenation]                   | *path* `+` *path*                          | left          | 7          |
+| [Path and string concatenation]        | *path* `+` *string*                        | left          | 7          |
+| [String and path concatenation]        | *string* `+` *path*                        | left          | 7          |
+| Logical negation (`NOT`)               | `!` *bool*                                 | none          | 8          |
+| [Update]                               | *attrset* `//` *attrset*                   | right         | 9          |
+| [Less than][Comparison]                | *expr* `<` *expr*                          | none          | 10         |
+| [Less than or equal to][Comparison]    | *expr* `<=` *expr*                         | none          | 10         |
+| [Greater than][Comparison]             | *expr* `>` *expr*                          | none          | 10         |
+| [Greater than or equal to][Comparison] | *expr* `>=` *expr*                         | none          | 10         |
+| [Equality]                             | *expr* `==` *expr*                         | none          | 11         |
+| Inequality                             | *expr* `!=` *expr*                         | none          | 11         |
+| Logical conjunction (`AND`)            | *bool* `&&` *bool*                         | left          | 12         |
+| Logical disjunction (`OR`)             | *bool* `||` *bool*                         | left          | 13         |
+| [Logical implication]                  | *bool* `->` *bool*                         | none          | 14         |
+
+[string]: ./values.md#type-string
+[path]: ./values.md#type-path
+[number]: ./values.md#type-number
+[list]: ./values.md#list
+[attribute set]: ./values.md#attribute-set
+
+## Attribute selection
+
+Select the attribute denoted by attribute path *attrpath* from [attribute set] *attrset*.
+If the attribute doesn’t exist, return *value* if provided, otherwise abort evaluation.
+
+<!-- FIXME: the following should to into its own language syntax section, but that needs more work to fit in well -->
+
+An attribute path is a dot-separated list of attribute names.
+An attribute name can be an identifier or a string.
+
+> *attrpath* = *name* [ `.` *name* ]...
+> *name* = *identifier* | *string*
+> *identifier* ~ `[a-zA-Z_][a-zA-Z0-9_'-]*`
+
+[Attribute selection]: #attribute-selection
+
+## Has attribute
+
+> *attrset* `?` *attrpath*
+
+Test whether [attribute set] *attrset* contains the attribute denoted by *attrpath*.
+The result is a [Boolean] value.
+
+[Boolean]: ./values.md#type-boolean
+
+[Has attribute]: #has-attribute
+
+## Arithmetic
+
+Numbers are type-compatible:
+Pure integer operations will always return integers, whereas any operation involving at least one floating point number return a floating point number.
+
+See also [Comparison] and [Equality].
+
+The `+` operator is overloaded to also work on strings and paths.
+
+[arithmetic]: #arithmetic
+
+## String concatenation
+
+> *string* `+` *string*
+
+Concatenate two [string]s and merge their string contexts.
+
+[String concatenation]: #string-concatenation
+
+## Path concatenation
+
+> *path* `+` *path*
+
+Concatenate two [path]s.
+The result is a path.
+
+[Path concatenation]: #path-concatenation
+
+## Path and string concatenation
+
+> *path* + *string*
+
+Concatenate *[path]* with *[string]*.
+The result is a path.
+
+> **Note**
+>
+> The string must not have a string context that refers to a [store path].
+
+[Path and string concatenation]: #path-and-string-concatenation
+
+## String and path concatenation
+
+> *string* + *path*
+
+Concatenate *[string]* with *[path]*.
+The result is a string.
+
+> **Important**
+>
+> The file or directory at *path* must exist and is copied to the [store].
+> The path appears in the result as the corresponding [store path].
+
+[store path]: ../glossary.md#gloss-store-path
+[store]: ../glossary.md#gloss-store
+
+[Path and string concatenation]: #path-and-string-concatenation
+
+## Update
+
+> *attrset1* + *attrset2*
+
+Update [attribute set] *attrset1* with names and values from *attrset2*.
+
+The returned attribute set will have of all the attributes in *e1* and *e2*.
+If an attribute name is present in both, the attribute value from the former is taken.
+
+[Update]: #update
+
+## Comparison
+
+Comparison is
+
+- [arithmetic] for [number]s 
+- lexicographic for [string]s and [path]s
+- item-wise lexicographic for [list]s:
+  elements at the same index in both lists are compared according to their type and skipped if they are equal.
+
+All comparison operators are implemented in terms of `<`, and the following equivalencies hold:
+
+| comparison   | implementation        |
+|--------------|-----------------------|
+| *a* `<=` *b* | `! (` *b* `<` *a* `)` |
+| *a* `>`  *b* |       *b* `<` *a*     |
+| *a* `>=` *b* | `! (` *a* `<` *b* `)` |
+
+[Comparison]: #comparison-operators
+
+## Equality
+
+- [Attribute sets][attribute set] and [list]s are compared recursively, and therefore are fully evaluated.
+- Comparison of [function]s always returns `false`.
+- Numbers are type-compatible, see [arithmetic] operators.
+- Floating point numbers only differ up to a limited precision.
+
+[function]: ./constructs.md#functions
+
+[Equality]: #equality
+
+## Logical implication
+
+Equivalent to `!`*b1* `||` *b2*.
+
+[Logical implication]: #logical-implication
+

doc/manual/src/language/string-interpolation.md

@@ -0,0 +1,82 @@
+# String interpolation
+
+String interpolation is a language feature where a [string], [path], or [attribute name] can contain expressions enclosed in `${ }` (dollar-sign with curly brackets).
+
+Such a string is an *interpolated string*, and an expression inside is an *interpolated expression*.
+
+Interpolated expressions must evaluate to one of the following:
+
+- a [string]
+- a [path]
+- a [derivation]
+
+[string]: ./values.md#type-string
+[path]: ./values.md#type-path
+[attribute name]: ./values.md#attribute-set
+[derivation]: ../glossary.md#gloss-derivation
+
+## Examples
+
+### String
+
+Rather than writing
+
+```nix
+"--with-freetype2-library=" + freetype + "/lib"
+```
+
+(where `freetype` is a [derivation]), you can instead write
+
+```nix
+"--with-freetype2-library=${freetype}/lib"
+```
+
+The latter is automatically translated to the former.
+
+A more complicated example (from the Nix expression for [Qt](http://www.trolltech.com/products/qt)):
+
+```nix
+configureFlags = "
+  -system-zlib -system-libpng -system-libjpeg
+  ${if openglSupport then "-dlopen-opengl
+    -L${mesa}/lib -I${mesa}/include
+    -L${libXmu}/lib -I${libXmu}/include" else ""}
+  ${if threadSupport then "-thread" else "-no-thread"}
+";
+```
+
+Note that Nix expressions and strings can be arbitrarily nested;
+in this case the outer string contains various interpolated expressions that themselves contain strings (e.g., `"-thread"`), some of which in turn contain interpolated expressions (e.g., `${mesa}`).
+
+### Path
+
+Rather than writing
+
+```nix
+./. + "/" + foo + "-" + bar + ".nix"
+```
+
+or
+
+```nix
+./. + "/${foo}-${bar}.nix"
+```
+
+you can instead write
+
+```nix
+./${foo}-${bar}.nix
+```
+
+### Attribute name
+
+Attribute names can be created dynamically with string interpolation:
+
+```nix
+let name = "foo"; in
+{
+  ${name} = "bar";
+}
+```
+
+    { foo = "bar"; }

doc/manual/src/language/values.md

@@ -0,0 +1,251 @@
+# Data Types
+
+## Primitives
+
+- <a id="type-string" href="#type-string">String</a>
+
+  *Strings* can be written in three ways.
+
+  The most common way is to enclose the string between double quotes,
+  e.g., `"foo bar"`. Strings can span multiple lines. The special
+  characters `"` and `\` and the character sequence `${` must be
+  escaped by prefixing them with a backslash (`\`). Newlines, carriage
+  returns and tabs can be written as `\n`, `\r` and `\t`,
+  respectively.
+
+  You can include the results of other expressions into a string by enclosing them in `${ }`, a feature known as [string interpolation].
+
+  [string interpolation]: ./string-interpolation.md
+
+  The second way to write string literals is as an *indented string*,
+  which is enclosed between pairs of *double single-quotes*, like so:
+
+  ```nix
+  ''
+    This is the first line.
+    This is the second line.
+      This is the third line.
+  ''
+  ```
+
+  This kind of string literal intelligently strips indentation from
+  the start of each line. To be precise, it strips from each line a
+  number of spaces equal to the minimal indentation of the string as a
+  whole (disregarding the indentation of empty lines). For instance,
+  the first and second line are indented two spaces, while the third
+  line is indented four spaces. Thus, two spaces are stripped from
+  each line, so the resulting string is
+
+  ```nix
+  "This is the first line.\nThis is the second line.\n  This is the third line.\n"
+  ```
+
+  Note that the whitespace and newline following the opening `''` is
+  ignored if there is no non-whitespace text on the initial line.
+
+  Indented strings support [string interpolation].
+
+  Since `${` and `''` have special meaning in indented strings, you
+  need a way to quote them. `$` can be escaped by prefixing it with
+  `''` (that is, two single quotes), i.e., `''$`. `''` can be escaped
+  by prefixing it with `'`, i.e., `'''`. `$` removes any special
+  meaning from the following `$`. Linefeed, carriage-return and tab
+  characters can be written as `''\n`, `''\r`, `''\t`, and `''\`
+  escapes any other character.
+
+  Indented strings are primarily useful in that they allow multi-line
+  string literals to follow the indentation of the enclosing Nix
+  expression, and that less escaping is typically necessary for
+  strings representing languages such as shell scripts and
+  configuration files because `''` is much less common than `"`.
+  Example:
+
+  ```nix
+  stdenv.mkDerivation {
+    ...
+    postInstall =
+      ''
+        mkdir $out/bin $out/etc
+        cp foo $out/bin
+        echo "Hello World" > $out/etc/foo.conf
+        ${if enableBar then "cp bar $out/bin" else ""}
+      '';
+    ...
+  }
+  ```
+
+  Finally, as a convenience, *URIs* as defined in appendix B of
+  [RFC 2396](http://www.ietf.org/rfc/rfc2396.txt) can be written *as
+  is*, without quotes. For instance, the string
+  `"http://example.org/foo.tar.bz2"` can also be written as
+  `http://example.org/foo.tar.bz2`.
+
+- <a id="type-number" href="#type-number">Number</a>
+
+  Numbers, which can be *integers* (like `123`) or *floating point*
+  (like `123.43` or `.27e13`).
+
+  See [arithmetic] and [comparison] operators for semantics.
+
+  [arithmetic]: ./operators.md#arithmetic
+  [comparison]: ./operators.md#comparison
+
+- <a id="type-path" href="#type-path">Path</a>
+
+  *Paths*, e.g., `/bin/sh` or `./builder.sh`. A path must contain at
+  least one slash to be recognised as such. For instance, `builder.sh`
+  is not a path: it's parsed as an expression that selects the
+  attribute `sh` from the variable `builder`. If the file name is
+  relative, i.e., if it does not begin with a slash, it is made
+  absolute at parse time relative to the directory of the Nix
+  expression that contained it. For instance, if a Nix expression in
+  `/foo/bar/bla.nix` refers to `../xyzzy/fnord.nix`, the absolute path
+  is `/foo/xyzzy/fnord.nix`.
+
+  If the first component of a path is a `~`, it is interpreted as if
+  the rest of the path were relative to the user's home directory.
+  e.g. `~/foo` would be equivalent to `/home/edolstra/foo` for a user
+  whose home directory is `/home/edolstra`.
+
+  Paths can also be specified between angle brackets, e.g.
+  `<nixpkgs>`. This means that the directories listed in the
+  environment variable `NIX_PATH` will be searched for the given file
+  or directory name.
+
+  When an [interpolated string][string interpolation] evaluates to a path, the path is first copied into the Nix store and the resulting string is the [store path] of the newly created [store object].
+
+  [store path]: ../glossary.md#gloss-store-path
+  [store object]: ../glossary.md#gloss-store-object
+
+  For instance, evaluating `"${./foo.txt}"` will cause `foo.txt` in the current directory to be copied into the Nix store and result in the string `"/nix/store/<hash>-foo.txt"`.
+
+  Note that the Nix language assumes that all input files will remain _unchanged_ while  evaluating a Nix expression.
+  For example, assume you used a file path in an interpolated string during a `nix repl` session.
+  Later in the same session, after having changed the file contents, evaluating the interpolated string with the file path again might not return a new store path, since Nix might not re-read the file contents.
+
+  Paths themselves, except those in angle brackets (`< >`), support [string interpolation].
+
+  At least one slash (`/`) must appear *before* any interpolated expression for the result to be recognized as a path.
+
+  `a.${foo}/b.${bar}` is a syntactically valid division operation.
+  `./a.${foo}/b.${bar}` is a path.
+
+- <a id="type-boolean" href="#type-boolean">Boolean</a>
+
+  *Booleans* with values `true` and `false`.
+
+- <a id="type-null" href="#type-null">Null</a>
+
+  The null value, denoted as `null`.
+
+## List
+
+Lists are formed by enclosing a whitespace-separated list of values
+between square brackets. For example,
+
+```nix
+[ 123 ./foo.nix "abc" (f { x = y; }) ]
+```
+
+defines a list of four elements, the last being the result of a call to
+the function `f`. Note that function calls have to be enclosed in
+parentheses. If they had been omitted, e.g.,
+
+```nix
+[ 123 ./foo.nix "abc" f { x = y; } ]
+```
+
+the result would be a list of five elements, the fourth one being a
+function and the fifth being a set.
+
+Note that lists are only lazy in values, and they are strict in length.
+
+## Attribute Set
+
+An attribute set is a collection of name-value-pairs (called *attributes*) enclosed in curly brackets (`{ }`).
+
+Names and values are separated by an equal sign (`=`).
+Each value is an arbitrary expression terminated by a semicolon (`;`).
+
+Attributes can appear in any order.
+An attribute name may only occur once.
+
+Example:
+
+```nix
+{
+  x = 123;
+  text = "Hello";
+  y = f { bla = 456; };
+}
+```
+
+This defines a set with attributes named `x`, `text`, `y`.
+
+Attributes can be selected from a set using the `.` operator. For
+instance,
+
+```nix
+{ a = "Foo"; b = "Bar"; }.a
+```
+
+evaluates to `"Foo"`. It is possible to provide a default value in an
+attribute selection using the `or` keyword. For example,
+
+```nix
+{ a = "Foo"; b = "Bar"; }.c or "Xyzzy"
+```
+
+will evaluate to `"Xyzzy"` because there is no `c` attribute in the set.
+
+You can use arbitrary double-quoted strings as attribute names:
+
+```nix
+{ "$!@#?" = 123; }."$!@#?"
+```
+
+```nix
+let bar = "bar";
+{ "foo ${bar}" = 123; }."foo ${bar}"
+```
+
+Both will evaluate to `123`.
+
+Attribute names support [string interpolation]:
+
+```nix
+let bar = "foo"; in
+{ foo = 123; }.${bar}
+```
+
+```nix
+let bar = "foo"; in
+{ ${bar} = 123; }.foo
+```
+
+Both will evaluate to `123`.
+
+In the special case where an attribute name inside of a set declaration
+evaluates to `null` (which is normally an error, as `null` cannot be coerced to
+a string), that attribute is simply not added to the set:
+
+```nix
+{ ${if foo then "bar" else null} = true; }
+```
+
+This will evaluate to `{}` if `foo` evaluates to `false`.
+
+A set that has a `__functor` attribute whose value is callable (i.e. is
+itself a function or a set with a `__functor` attribute whose value is
+callable) can be applied as if it were a function, with the set itself
+passed in first , e.g.,
+
+```nix
+let add = { __functor = self: x: x + self.x; };
+    inc = add // { x = 1; };
+in inc 1
+```
+
+evaluates to `2`. This can be used to attach metadata to a function
+without the caller needing to treat it specially, or to implement a form
+of object-oriented programming, for example.

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

@@ -1,5 +1,4 @@
 This chapter discusses how to do package management with Nix, i.e.,
 how to obtain, install, upgrade, and erase packages. This is the
 “user’s” perspective of the Nix system — people who want to *create*
-packages should consult the [chapter on writing Nix
-expressions](../expressions/writing-nix-expressions.md).
+packages should consult the chapter on the [Nix language](../language/index.md).

doc/manual/src/release-notes/rl-2.11.md

@@ -0,0 +1,5 @@
+# Release 2.11 (2022-08-24)
+
+* `nix copy` now copies the store paths in parallel as much as possible (again).
+  This doesn't apply for the `daemon` and `ssh-ng` stores which copy everything
+  in one batch to avoid latencies issues.

doc/manual/src/release-notes/rl-2.12.md

@@ -0,0 +1,43 @@
+# Release 2.12 (2022-12-06)
+
+* On Linux, Nix can now run builds in a user namespace where they run
+  as root (UID 0) and have 65,536 UIDs available.
+  <!-- FIXME: move this to its own section about system features -->
+  This is primarily useful for running containers such as `systemd-nspawn`
+  inside a Nix build. For an example, see [`tests/systemd-nspawn/nix`][nspawn].
+
+  [nspawn]: https://github.com/NixOS/nix/blob/67bcb99700a0da1395fa063d7c6586740b304598/tests/systemd-nspawn.nix.
+
+  A build can enable this by setting the derivation attribute:
+
+  ```
+  requiredSystemFeatures = [ "uid-range" ];
+  ```
+
+  The `uid-range` [system feature] requires the [`auto-allocate-uids`]
+  setting to be enabled.
+
+  [system feature]: ../command-ref/conf-file.md#conf-system-features
+
+* Nix can now automatically pick UIDs for builds, removing the need to
+  create `nixbld*` user accounts. See [`auto-allocate-uids`].
+
+  [`auto-allocate-uids`]: ../command-ref/conf-file.md#conf-auto-allocate-uids
+
+* On Linux, Nix has experimental support for running builds inside a
+  cgroup. See
+  [`use-cgroups`](../command-ref/conf-file.md#conf-use-cgroups).
+
+* `<nix/fetchurl.nix>` now accepts an additional argument `impure` which
+  defaults to `false`.  If it is set to `true`, the `hash` and `sha256`
+  arguments will be ignored and the resulting derivation will have
+  `__impure` set to `true`, making it an impure derivation.
+
+* If `builtins.readFile` is called on a file with context, then only
+  the parts of the context that appear in the content of the file are
+  retained.  This avoids a lot of spurious errors where strings end up
+  having a context just because they are read from a store path
+  ([#7260](https://github.com/NixOS/nix/pull/7260)).
+
+* `nix build --json` now prints some statistics about top-level
+  derivations, such as CPU statistics when cgroups are enabled.

doc/manual/src/release-notes/rl-2.13.md

@@ -0,0 +1,40 @@
+# Release 2.13 (2023-01-17)
+
+* The `repeat` and `enforce-determinism` options have been removed
+  since they had been broken under many circumstances for a long time.
+
+* You can now use [flake references] in the [old command line interface], e.g.
+
+   [flake references]: ../command-ref/new-cli/nix3-flake.md#flake-references
+   [old command line interface]: ../command-ref/main-commands.md
+
+  ```shell-session
+  # nix-build flake:nixpkgs -A hello
+  # nix-build -I nixpkgs=flake:github:NixOS/nixpkgs/nixos-22.05 \
+      '<nixpkgs>' -A hello
+  # NIX_PATH=nixpkgs=flake:nixpkgs nix-build '<nixpkgs>' -A hello
+  ```
+
+* Instead of "antiquotation", the more common term [string interpolation](../language/string-interpolation.md) is now used consistently.
+  Historical release notes were not changed.
+
+* Allow explicitly selecting outputs in a store derivation installable, just like we can do with other sorts of installables.
+  For example,
+  ```shell-session
+  # nix build /nix/store/gzaflydcr6sb3567hap9q6srzx8ggdgg-glibc-2.33-78.drv^dev
+  ```
+  now works just as
+  ```shell-session
+  # nix build nixpkgs#glibc^dev
+  ```
+  does already.
+
+* On Linux, `nix develop` now sets the
+  [*personality*](https://man7.org/linux/man-pages/man2/personality.2.html)
+  for the development shell in the same way as the actual build of the
+  derivation. This makes shells for `i686-linux` derivations work
+  correctly on `x86_64-linux`.
+
+* You can now disable the global flake registry by setting the `flake-registry`
+  configuration option to an empty string. The same can be achieved at runtime with
+  `--flake-registry ""`.

doc/manual/utils.nix

@@ -5,6 +5,32 @@ rec {
 
   concatStrings = concatStringsSep "";
 
+  replaceStringsRec = from: to: string:
+    # recursively replace occurrences of `from` with `to` within `string`
+    # example:
+    #     replaceStringRec "--" "-" "hello-----world"
+    #     => "hello-world"
+    let
+      replaced = replaceStrings [ from ] [ to ] string;
+    in
+      if replaced == string then string else replaceStringsRec from to replaced;
+
+  squash = replaceStringsRec "\n\n\n" "\n\n";
+
+  trim = string:
+    # trim trailing spaces and squash non-leading spaces
+    let
+      trimLine = line:
+        let
+          # separate leading spaces from the rest
+          parts = split "(^ *)" line;
+          spaces = head (elemAt parts 1);
+          rest = elemAt parts 2;
+          # drop trailing spaces
+          body = head (split " *$" rest);
+        in spaces + replaceStringsRec "  " " " body;
+    in concatStringsSep "\n" (map trimLine (splitLines string));
+
   # FIXME: O(n^2)
   unique = foldl' (acc: e: if elem e acc then acc else acc ++ [ e ]) [];
 

docker.nix

@@ -2,10 +2,12 @@
 , lib ? pkgs.lib
 , name ? "nix"
 , tag ? "latest"
+, bundleNixpkgs ? true
 , channelName ? "nixpkgs"
 , channelURL ? "https://nixos.org/channels/nixpkgs-unstable"
 , extraPkgs ? []
 , maxLayers ? 100
+, nixConf ? {}
 }:
 let
   defaultPkgs = with pkgs; [
@@ -31,9 +33,20 @@ let
 
     root = {
       uid = 0;
-      shell = "/bin/bash";
+      shell = "${pkgs.bashInteractive}/bin/bash";
       home = "/root";
       gid = 0;
+      groups = [ "root" ];
+      description = "System administrator";
+    };
+
+    nobody = {
+      uid = 65534;
+      shell = "${pkgs.shadow}/bin/nologin";
+      home = "/var/empty";
+      gid = 65534;
+      groups = [ "nobody" ];
+      description = "Unprivileged account (don't use!)";
     };
 
   } // lib.listToAttrs (
@@ -55,6 +68,7 @@ let
   groups = {
     root.gid = 0;
     nixbld.gid = 30000;
+    nobody.gid = 65534;
   };
 
   userToPasswd = (
@@ -123,20 +137,27 @@ let
       (lib.attrValues (lib.mapAttrs groupToGroup groups))
   );
 
-  nixConf = {
+  defaultNixConf = {
     sandbox = "false";
     build-users-group = "nixbld";
-    trusted-public-keys = "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=";
+    trusted-public-keys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
   };
-  nixConfContents = (lib.concatStringsSep "\n" (lib.mapAttrsFlatten (n: v: "${n} = ${v}") nixConf)) + "\n";
+
+  nixConfContents = (lib.concatStringsSep "\n" (lib.mapAttrsFlatten (n: v:
+    let
+      vStr = if builtins.isList v then lib.concatStringsSep " " v else v;
+    in
+      "${n} = ${vStr}") (defaultNixConf // nixConf))) + "\n";
 
   baseSystem =
     let
       nixpkgs = pkgs.path;
-      channel = pkgs.runCommand "channel-nixos" { } ''
+      channel = pkgs.runCommand "channel-nixos" { inherit bundleNixpkgs; } ''
         mkdir $out
-        ln -s ${nixpkgs} $out/nixpkgs
-        echo "[]" > $out/manifest.nix
+        if [ "$bundleNixpkgs" ]; then
+          ln -s ${nixpkgs} $out/nixpkgs
+          echo "[]" > $out/manifest.nix
+        fi
       '';
       rootEnv = pkgs.buildPackages.buildEnv {
         name = "root-profile-env";

flake.lock

@@ -18,16 +18,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1653988320,
-        "narHash": "sha256-ZaqFFsSDipZ6KVqriwM34T739+KLYJvNmCWzErjAg7c=",
+        "lastModified": 1670461440,
+        "narHash": "sha256-jy1LB8HOMKGJEGXgzFRLDU1CBGL0/LlkolgnqIsF0D8=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "2fa57ed190fd6c7c746319444f34b5917666e5c1",
+        "rev": "04a75b2eecc0acf6239acf9dd04485ff8d14f425",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-22.05-small",
+        "ref": "nixos-22.11-small",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -1,7 +1,7 @@
 {
   description = "The purely functional package manager";
 
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-22.05-small";
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-22.11-small";
   inputs.nixpkgs-regression.url = "github:NixOS/nixpkgs/215d4d0fd80ca5163643b03a33fde804a29cc1e2";
   inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
 
@@ -9,21 +9,21 @@
 
     let
 
-      version = builtins.readFile ./.version + versionSuffix;
+      officialRelease = true;
+
+      version = nixpkgs.lib.fileContents ./.version + versionSuffix;
       versionSuffix =
         if officialRelease
         then ""
         else "pre${builtins.substring 0 8 (self.lastModifiedDate or self.lastModified or "19700101")}_${self.shortRev or "dirty"}";
 
-      officialRelease = false;
-
       linux64BitSystems = [ "x86_64-linux" "aarch64-linux" ];
       linuxSystems = linux64BitSystems ++ [ "i686-linux" ];
       systems = linuxSystems ++ [ "x86_64-darwin" "aarch64-darwin" ];
 
       crossSystems = [ "armv6l-linux" "armv7l-linux" ];
 
-      stdenvs = [ "gccStdenv" "clangStdenv" "clang11Stdenv" "stdenv" "libcxxStdenv" ];
+      stdenvs = [ "gccStdenv" "clangStdenv" "clang11Stdenv" "stdenv" "libcxxStdenv" "ccacheStdenv" ];
 
       forAllSystems = f: nixpkgs.lib.genAttrs systems (system: f system);
       forAllSystemsAndStdenvs = f: forAllSystems (system:
@@ -96,6 +96,7 @@
             buildPackages.flex
             (lib.getBin buildPackages.lowdown-nix)
             buildPackages.mdbook
+            buildPackages.mdbook-linkcheck
             buildPackages.autoconf-archive
             buildPackages.autoreconfHook
             buildPackages.pkg-config
@@ -133,7 +134,8 @@
               patches = (o.patches or []) ++ [
                 ./boehmgc-coroutine-sp-fallback.diff
               ];
-            }))
+            })
+            )
             nlohmann_json
           ];
       };
@@ -260,6 +262,7 @@
             echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
             tar cvfJ $fn \
               --owner=0 --group=0 --mode=u+rw,uga+r \
+              --mtime='1970-01-01' \
               --absolute-names \
               --hard-dereference \
               --transform "s,$TMPDIR/install,$dir/install," \
@@ -419,6 +422,8 @@
         buildCross = nixpkgs.lib.genAttrs crossSystems (crossSystem:
           nixpkgs.lib.genAttrs ["x86_64-linux"] (system: self.packages.${system}."nix-${crossSystem}"));
 
+        buildNoGc = nixpkgs.lib.genAttrs systems (system: self.packages.${system}.nix.overrideAttrs (a: { configureFlags = (a.configureFlags or []) ++ ["--enable-gc=no"];}));
+
         # Perl bindings for various platforms.
         perlBindings = nixpkgs.lib.genAttrs systems (system: self.packages.${system}.nix.perl-bindings);
 
@@ -505,6 +510,12 @@
           overlay = self.overlays.default;
         });
 
+        tests.containers = (import ./tests/containers.nix rec {
+          system = "x86_64-linux";
+          inherit nixpkgs;
+          overlay = self.overlays.default;
+        });
+
         tests.setuid = nixpkgs.lib.genAttrs
           ["i686-linux" "x86_64-linux"]
           (system:
@@ -526,6 +537,12 @@
               mkdir $out
             '';
 
+        tests.nixpkgsLibTests =
+          nixpkgs.lib.genAttrs systems (system:
+            import (nixpkgs + "/lib/tests/release.nix")
+              { pkgs = nixpkgsFor.${system}; }
+          );
+
         metrics.nixpkgs = import "${nixpkgs-regression}/pkgs/top-level/metrics.nix" {
           pkgs = nixpkgsFor.x86_64-linux;
           nixpkgs = nixpkgs-regression;
@@ -545,12 +562,18 @@
             # againstLatestStable = testNixVersions pkgs pkgs.nix pkgs.nixStable;
           } "touch $out");
 
+        installerTests = import ./tests/installer {
+          binaryTarballs = self.hydraJobs.binaryTarball;
+          inherit nixpkgsFor;
+        };
+
       };
 
       checks = forAllSystems (system: {
         binaryTarball = self.hydraJobs.binaryTarball.${system};
         perlBindings = self.hydraJobs.perlBindings.${system};
         installTests = self.hydraJobs.installTests.${system};
+        nixpkgsLibTests = self.hydraJobs.tests.nixpkgsLibTests.${system};
       } // (nixpkgs.lib.optionalAttrs (builtins.elem system linux64BitSystems)) {
         dockerImage = self.hydraJobs.dockerImage.${system};
       });

maintainers/README.md

@@ -0,0 +1,107 @@
+# Nix maintainers team
+
+## Motivation
+
+The goal of the team is to help other people to contribute to Nix.
+
+## Members
+
+- Eelco Dolstra (@edolstra) – Team lead
+- Théophane Hufschmitt (@thufschmitt)
+- Valentin Gagarin (@fricklerhandwerk)
+- Thomas Bereknyei (@tomberek)
+- Robert Hensing (@roberth)
+
+## Meeting protocol
+
+The team meets twice a week:
+
+- Discussion meeting: [Fridays 13:00-14:00 CET](https://calendar.google.com/calendar/event?eid=MHNtOGVuNWtrZXNpZHR2bW1sM3QyN2ZjaGNfMjAyMjExMjVUMTIwMDAwWiBiOW81MmZvYnFqYWs4b3E4bGZraGczdDBxZ0Bn)
+
+  1. Triage issues and pull requests from the _No Status_ column (30 min)
+  2. Discuss issues and pull requests from the _To discuss_ column (30 min)
+
+- Work meeting: [Mondays 13:00-15:00 CET](https://calendar.google.com/calendar/event?eid=NTM1MG1wNGJnOGpmOTZhYms3bTB1bnY5cWxfMjAyMjExMjFUMTIwMDAwWiBiOW81MmZvYnFqYWs4b3E4bGZraGczdDBxZ0Bn)
+
+  1. Code review on pull requests from _In review_.
+  2. Other chores and tasks.
+
+Meeting notes are collected on a [collaborative scratchpad](https://pad.lassul.us/Cv7FpYx-Ri-4VjUykQOLAw), and published on Discourse under the [Nix category](https://discourse.nixos.org/c/dev/nix/50).
+
+## Project board protocol
+
+The team uses a [GitHub project board](https://github.com/orgs/NixOS/projects/19/views/1) for tracking its work.
+
+Issues on the board progress through the following states:
+
+- No Status
+
+  During the discussion meeting, the team triages new items.
+  To be considered, issues and pull requests must have a high-level description to provide the whole team with the necessary context at a glance.
+
+  On every meeting, at least one item from each of the following categories is inspected:
+
+  1. [critical](https://github.com/NixOS/nix/labels/critical)
+  2. [security](https://github.com/NixOS/nix/labels/security)
+  3. [regression](https://github.com/NixOS/nix/labels/regression)
+  4. [bug](https://github.com/NixOS/nix/issues?q=is%3Aopen+label%3Abug+sort%3Areactions-%2B1-desc)
+
+  - [oldest pull requests](https://github.com/NixOS/nix/pulls?q=is%3Apr+is%3Aopen+sort%3Acreated-asc)
+  - [most popular pull requests](https://github.com/NixOS/nix/pulls?q=is%3Apr+is%3Aopen+sort%3Areactions-%2B1-desc)
+  - [oldest issues](https://github.com/NixOS/nix/issues?q=is%3Aissue+is%3Aopen+sort%3Acreated-asc)
+  - [most popular issues](https://github.com/NixOS/nix/issues?q=is%3Aissue+is%3Aopen+sort%3Areactions-%2B1-desc)
+
+  Team members can also add pull requests or issues they would like the whole team to consider.
+
+  If there is disagreement on the general idea behind an issue or pull request, it is moved to _To discuss_, otherwise to _In review_.
+
+- To discuss
+
+  Pull requests and issues that are deemed important and controversial are discussed by the team during discussion meetings.
+
+  This may be where the merit of the change itself or the implementation strategy is contested by a team member.
+
+  As a general guideline, the order of items is determined as follows:
+
+  - Prioritise pull requests over issues
+
+    Contributors who took the time to implement concrete change proposals should not wait indefinitely.
+
+  - Prioritise fixing bugs over documentation, improvements or new features
+
+    The team values stability and accessibility higher than raw functionality.
+
+  - Interleave issues and PRs
+
+    This way issues without attempts at a solution get a chance to get addressed.
+
+- In review
+
+  Pull requests in this column are reviewed together during work meetings.
+  This is both for spreading implementation knowledge and for establishing common values in code reviews.
+
+  When the overall direction is agreed upon, even when further changes are required, the pull request is assigned to one team member.
+
+- Assigned for merging
+
+  One team member is assigned to each of these pull requests.
+  They will communicate with the authors, and make the final approval once all remaining issues are addressed.
+
+  If more substantive issues arise, the assignee can move the pull request back to _To discuss_ to involve the team again.
+
+The process is illustrated in the following diagram:
+
+```mermaid
+flowchart TD
+    discuss[To discuss]
+
+    review[To review]
+
+    New --> |Disagreement on idea| discuss
+    New & discuss --> |Consensus on idea| review
+
+    review --> |Consensus on implementation| Assigned
+
+    Assigned --> |Implementation issues arise| review
+    Assigned --> |Remaining issues fixed| Merged
+```

maintainers/upload-release.pl

@@ -115,10 +115,6 @@ sub downloadFile {
 
     write_file("$tmpFile.sha256", $sha256_actual);
 
-    if (! -e "$tmpFile.asc") {
-        system("gpg2 --detach-sign --armor $tmpFile") == 0 or die "unable to sign $tmpFile\n";
-    }
-
     return $sha256_expected;
 }
 
@@ -194,7 +190,7 @@ for my $fn (glob "$tmpDir/*") {
         my $configuration = ();
         $configuration->{content_type} = "application/octet-stream";
 
-        if ($fn =~ /.sha256|.asc|install/) {
+        if ($fn =~ /.sha256|install/) {
             # Text files
             $configuration->{content_type} = "text/plain";
         }

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

@@ -28,7 +28,7 @@
     <key>SoftResourceLimits</key>
     <dict>
       <key>NumberOfFiles</key>
-      <integer>4096</integer>
+      <integer>1048576</integer>
     </dict>
   </dict>
 </plist>

misc/systemd/nix-daemon.service.in

@@ -9,7 +9,7 @@ ConditionPathIsReadWrite=@localstatedir@/nix/daemon-socket
 [Service]
 ExecStart=@@bindir@/nix-daemon nix-daemon --daemon
 KillMode=process
-LimitNOFILE=4096
+LimitNOFILE=1048576
 
 [Install]
 WantedBy=multi-user.target

misc/zsh/completion.zsh

@@ -10,14 +10,15 @@ function _nix() {
   local -a suggestions
   declare -a suggestions
   for suggestion in ${res:1}; do
-    # FIXME: This doesn't work properly if the suggestion word contains a `:`
-    # itself
-    suggestions+="${suggestion/	/:}"
+    suggestions+=("${suggestion%%	*}")
   done
+  local -a args
   if [[ "$tpe" == filenames ]]; then
-    compadd -f
+    args+=('-f')
+  elif [[ "$tpe" == attrs ]]; then
+    args+=('-S' '')
   fi
-  _describe 'nix' suggestions
+  compadd -J nix "${args[@]}" -a suggestions
 }
 
 _nix "$@"

mk/common-test.sh

@@ -0,0 +1,11 @@
+TESTS_ENVIRONMENT=("TEST_NAME=${test%.*}" 'NIX_REMOTE=')
+
+: ${BASH:=/usr/bin/env bash}
+
+init_test () {
+   cd tests && env "${TESTS_ENVIRONMENT[@]}" $BASH -e init.sh 2>/dev/null > /dev/null
+}
+
+run_test_proper () {
+   cd $(dirname $test) && env "${TESTS_ENVIRONMENT[@]}" $BASH -e $(basename $test)
+}

mk/debug-test.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+
+set -eu
+
+test=$1
+
+dir="$(dirname "${BASH_SOURCE[0]}")"
+source "$dir/common-test.sh"
+
+(init_test)
+run_test_proper

mk/run-test.sh

@@ -1,4 +1,4 @@
-#!/bin/sh
+#!/usr/bin/env bash
 
 set -u
 
@@ -7,7 +7,12 @@ green=""
 yellow=""
 normal=""
 
-post_run_msg="ran test $1..."
+test=$1
+
+dir="$(dirname "${BASH_SOURCE[0]}")"
+source "$dir/common-test.sh"
+
+post_run_msg="ran test $test..."
 if [ -t 1 ]; then
     red=""
     green=""
@@ -16,12 +21,12 @@ if [ -t 1 ]; then
 fi
 
 run_test () {
-    (cd tests && env ${TESTS_ENVIRONMENT} init.sh 2>/dev/null > /dev/null)
-    log="$(cd $(dirname $1) && env ${TESTS_ENVIRONMENT} $(basename $1) 2>&1)"
+    (init_test 2>/dev/null > /dev/null)
+    log="$(run_test_proper 2>&1)"
     status=$?
 }
 
-run_test "$1"
+run_test
 
 # Hack: Retry the test if it fails with “unexpected EOF reading a line” as these
 # appear randomly without anyone knowing why.
@@ -32,7 +37,7 @@ if [[ $status -ne 0 && $status -ne 99 && \
 ]]; then
     echo "$post_run_msg [${yellow}FAIL$normal] (possibly flaky, so will be retried)"
     echo "$log" | sed 's/^/    /'
-    run_test "$1"
+    run_test
 fi
 
 if [ $status -eq 0 ]; then

mk/tests.mk

@@ -8,7 +8,11 @@ define run-install-test
 
   .PHONY: $1.test
   $1.test: $1 $(test-deps)
-	@env TEST_NAME=$(basename $1) TESTS_ENVIRONMENT="$(tests-environment)" mk/run_test.sh $1 < /dev/null
+	@env BASH=$(bash) $(bash) mk/run-test.sh $1 < /dev/null
+
+  .PHONY: $1.test-debug
+  $1.test-debug: $1 $(test-deps)
+	@env BASH=$(bash) $(bash) mk/debug-test.sh $1 < /dev/null
 
 endef
 

scripts/install-darwin-multi-user.sh

@@ -167,7 +167,7 @@ poly_user_shell_get() {
 }
 
 poly_user_shell_set() {
-    _sudo "in order to give $1 a safe home directory" \
+    _sudo "in order to give $1 a safe shell" \
           /usr/bin/dscl . -create "/Users/$1" "UserShell" "$2"
 }
 

scripts/install-multi-user.sh

@@ -37,6 +37,19 @@ readonly PROFILE_TARGETS=("/etc/bashrc" "/etc/profile.d/nix.sh" "/etc/zshrc" "/e
 readonly PROFILE_BACKUP_SUFFIX=".backup-before-nix"
 readonly PROFILE_NIX_FILE="$NIX_ROOT/var/nix/profiles/default/etc/profile.d/nix-daemon.sh"
 
+# Fish has different syntax than zsh/bash, treat it separate
+readonly PROFILE_FISH_SUFFIX="conf.d/nix.fish"
+readonly PROFILE_FISH_PREFIXES=(
+    # each of these are common values of $__fish_sysconf_dir,
+    # under which Fish will look for a file named
+    # $PROFILE_FISH_SUFFIX.
+    "/etc/fish"              # standard
+    "/usr/local/etc/fish"    # their installer .pkg for macOS
+    "/opt/homebrew/etc/fish" # homebrew
+    "/opt/local/etc/fish"    # macports
+)
+readonly PROFILE_NIX_FILE_FISH="$NIX_ROOT/var/nix/profiles/default/etc/profile.d/nix-daemon.fish"
+
 readonly NIX_INSTALLED_NIX="@nix@"
 readonly NIX_INSTALLED_CACERT="@cacert@"
 #readonly NIX_INSTALLED_NIX="/nix/store/j8dbv5w6jl34caywh2ygdy88knx1mdf7-nix-2.3.6"
@@ -45,7 +58,7 @@ readonly EXTRACTED_NIX_PATH="$(dirname "$0")"
 
 readonly ROOT_HOME=~root
 
-if [ -t 0 ]; then
+if [ -t 0 ] && [ -z "${NIX_INSTALLER_YES:-}" ]; then
     readonly IS_HEADLESS='no'
 else
     readonly IS_HEADLESS='yes'
@@ -59,14 +72,35 @@ headless() {
     fi
 }
 
+is_root() {
+    if [ "$EUID" -eq 0 ]; then
+        return 0
+    else
+        return 1
+    fi
+}
+
+is_os_linux() {
+    if [ "$(uname -s)" = "Linux" ]; then
+        return 0
+    else
+        return 1
+    fi
+}
+
+is_os_darwin() {
+    if [ "$(uname -s)" = "Darwin" ]; then
+        return 0
+    else
+        return 1
+    fi
+}
+
 contact_us() {
-    echo "You can open an issue at https://github.com/nixos/nix/issues"
+    echo "You can open an issue at"
+    echo "https://github.com/NixOS/nix/issues/new?labels=installer&template=installer.md"
     echo ""
-    echo "Or feel free to contact the team:"
-    echo " - Matrix: #nix:nixos.org"
-    echo " - IRC: in #nixos on irc.libera.chat"
-    echo " - twitter: @nixos_org"
-    echo " - forum: https://discourse.nixos.org"
+    echo "Or get in touch with the community: https://nixos.org/community"
 }
 get_help() {
     echo "We'd love to help if you need it."
@@ -313,14 +347,23 @@ __sudo() {
 _sudo() {
     local expl="$1"
     shift
-    if ! headless; then
+    if ! headless || is_root; then
         __sudo "$expl" "$*" >&2
     fi
-    sudo "$@"
+
+    if is_root; then
+        env "$@"
+    else
+        sudo "$@"
+    fi
 }
 
+# Ensure that $TMPDIR exists if defined.
+if [[ -n "${TMPDIR:-}" ]] && [[ ! -d "${TMPDIR:-}" ]]; then
+    mkdir -m 0700 -p "${TMPDIR:-}"
+fi
 
-readonly SCRATCH=$(mktemp -d "${TMPDIR:-/tmp/}tmp.XXXXXXXXXX")
+readonly SCRATCH=$(mktemp -d)
 finish_cleanup() {
     rm -rf "$SCRATCH"
 }
@@ -329,7 +372,7 @@ finish_fail() {
     finish_cleanup
 
     failure <<EOF
-Jeeze, something went wrong. If you can take all the output and open
+Oh no, something went wrong. If you can take all the output and open
 an issue, we'd love to fix the problem so nobody else has this issue.
 
 :(
@@ -423,7 +466,7 @@ EOF
         fi
     done
 
-    if [ "$(uname -s)" = "Linux" ] && [ ! -e /run/systemd/system ]; then
+    if is_os_linux && [ ! -e /run/systemd/system ]; then
         warning <<EOF
 We did not detect systemd on your system. With a multi-user install
 without systemd you will have to manually configure your init system to
@@ -532,7 +575,7 @@ EOF
     # to extract _just_ the user's note, instead it is prefixed with
     # some plist junk. This was causing the user note to always be set,
     # even if there was no reason for it.
-    if ! poly_user_note_get "$username" | grep -q "Nix build user $coreid"; then
+    if poly_user_note_get "$username" | grep -q "Nix build user $coreid"; then
         row "              Note" "Nix build user $coreid"
     else
         poly_user_note_set "$username" "Nix build user $coreid"
@@ -640,7 +683,7 @@ place_channel_configuration() {
 
 check_selinux() {
     if command -v getenforce > /dev/null 2>&1; then
-        if ! [ "$(getenforce)" = "Disabled" ]; then
+        if [ "$(getenforce)" = "Enforcing" ]; then
             failure <<EOF
 Nix does not work with selinux enabled yet!
 see https://github.com/NixOS/nix/issues/2374
@@ -777,7 +820,7 @@ EOF
         fi
 
         _sudo "to load data for the first time in to the Nix Database" \
-              "$NIX_INSTALLED_NIX/bin/nix-store" --load-db < ./.reginfo
+              HOME="$ROOT_HOME" "$NIX_INSTALLED_NIX/bin/nix-store" --load-db < ./.reginfo
 
         echo "      Just finished getting the nix database ready."
     )
@@ -795,6 +838,19 @@ fi
 EOF
 }
 
+# Fish has differing syntax
+fish_source_lines() {
+    cat <<EOF
+
+# Nix
+if test -e '$PROFILE_NIX_FILE_FISH'
+  . '$PROFILE_NIX_FILE_FISH'
+end
+# End Nix
+
+EOF
+}
+
 configure_shell_profile() {
     task "Setting up shell profiles: ${PROFILE_TARGETS[*]}"
     for profile_target in "${PROFILE_TARGETS[@]}"; do
@@ -816,6 +872,27 @@ configure_shell_profile() {
                         tee -a "$profile_target"
         fi
     done
+
+    task "Setting up shell profiles for Fish with with ${PROFILE_FISH_SUFFIX} inside ${PROFILE_FISH_PREFIXES[*]}"
+    for fish_prefix in "${PROFILE_FISH_PREFIXES[@]}"; do
+        if [ ! -d "$fish_prefix" ]; then
+            # this specific prefix (ie: /etc/fish) is very likely to exist
+            # if Fish is installed with this sysconfdir.
+            continue
+        fi
+
+        profile_target="${fish_prefix}/${PROFILE_FISH_SUFFIX}"
+        conf_dir=$(dirname "$profile_target")
+        if [ ! -d "$conf_dir" ]; then
+            _sudo "create $conf_dir for our Fish hook" \
+                mkdir "$conf_dir"
+        fi
+
+        fish_source_lines \
+            | _sudo "write nix-daemon settings to $profile_target" \
+                    tee "$profile_target"
+    done
+
     # TODO: should we suggest '. $PROFILE_NIX_FILE'? It would get them on
     # their way less disruptively, but a counter-argument is that they won't
     # immediately notice if something didn't get set up right?
@@ -865,24 +942,14 @@ EOF
           install -m 0664 "$SCRATCH/nix.conf" /etc/nix/nix.conf
 }
 
-main() {
-    # TODO: I've moved this out of validate_starting_assumptions so we
-    # can fail faster in this case. Sourcing install-darwin... now runs
-    # `touch /` to detect Read-only root, but it could update times on
-    # pre-Catalina macOS if run as root user.
-    if [ "$EUID" -eq 0 ]; then
-        failure <<EOF
-Please do not run this script with root privileges. I will call sudo
-when I need to.
-EOF
-    fi
 
+main() {
     check_selinux
 
-    if [ "$(uname -s)" = "Darwin" ]; then
+    if is_os_darwin; then
         # shellcheck source=./install-darwin-multi-user.sh
         . "$EXTRACTED_NIX_PATH/install-darwin-multi-user.sh"
-    elif [ "$(uname -s)" = "Linux" ]; then
+    elif is_os_linux; then
         # shellcheck source=./install-systemd-multi-user.sh
         . "$EXTRACTED_NIX_PATH/install-systemd-multi-user.sh" # most of this works on non-systemd distros also
     else
@@ -890,7 +957,10 @@ EOF
     fi
 
     welcome_to_nix
-    chat_about_sudo
+
+    if ! is_root; then
+        chat_about_sudo
+    fi
 
     cure_artifacts
     # TODO: there's a tension between cure and validate. I moved the

scripts/install-nix-from-closure.sh

@@ -71,6 +71,8 @@ while [ $# -gt 0 ]; do
         #     # intentional tail space
         #     ACTIONS="${ACTIONS}uninstall "
         #     ;;
+        --yes)
+            export NIX_INSTALLER_YES=1;;
         --no-channel-add)
             export NIX_INSTALLER_NO_CHANNEL_ADD=1;;
         --daemon-user-count)
@@ -90,7 +92,7 @@ while [ $# -gt 0 ]; do
             shift;;
         *)
             {
-                echo "Nix Installer [--daemon|--no-daemon] [--daemon-user-count INT] [--no-channel-add] [--no-modify-profile] [--nix-extra-conf-file FILE]"
+                echo "Nix Installer [--daemon|--no-daemon] [--daemon-user-count INT] [--yes] [--no-channel-add] [--no-modify-profile] [--nix-extra-conf-file FILE]"
 
                 echo "Choose installation method."
                 echo ""
@@ -104,6 +106,8 @@ while [ $# -gt 0 ]; do
                 echo "              trivial to uninstall."
                 echo "              (default)"
                 echo ""
+                echo " --yes:               Run the script non-interactively, accepting all prompts."
+                echo ""
                 echo " --no-channel-add:    Don't add any channels. nixpkgs-unstable is installed by default."
                 echo ""
                 echo " --no-modify-profile: Don't modify the user profile to automatically load nix."
@@ -148,7 +152,9 @@ if ! [ -w "$dest" ]; then
     exit 1
 fi
 
-mkdir -p "$dest/store"
+# The auto-chroot code in openFromNonUri() checks for the
+# non-existence of /nix/var/nix, so we need to create it here.
+mkdir -p "$dest/store" "$dest/var/nix"
 
 printf "copying Nix to %s..." "${dest}/store" >&2
 # Insert a newline if no progress is shown.
@@ -207,31 +213,50 @@ if [ -z "$NIX_INSTALLER_NO_CHANNEL_ADD" ]; then
 fi
 
 added=
-p=$HOME/.nix-profile/etc/profile.d/nix.sh
+p=
+p_sh=$HOME/.nix-profile/etc/profile.d/nix.sh
+p_fish=$HOME/.nix-profile/etc/profile.d/nix.fish
 if [ -z "$NIX_INSTALLER_NO_MODIFY_PROFILE" ]; then
     # Make the shell source nix.sh during login.
     for i in .bash_profile .bash_login .profile; do
         fn="$HOME/$i"
         if [ -w "$fn" ]; then
-            if ! grep -q "$p" "$fn"; then
+            if ! grep -q "$p_sh" "$fn"; then
                 echo "modifying $fn..." >&2
-                printf '\nif [ -e %s ]; then . %s; fi # added by Nix installer\n' "$p" "$p" >> "$fn"
+                printf '\nif [ -e %s ]; then . %s; fi # added by Nix installer\n' "$p_sh" "$p_sh" >> "$fn"
             fi
             added=1
+            p=${p_sh}
             break
         fi
     done
     for i in .zshenv .zshrc; do
         fn="$HOME/$i"
         if [ -w "$fn" ]; then
-            if ! grep -q "$p" "$fn"; then
+            if ! grep -q "$p_sh" "$fn"; then
                 echo "modifying $fn..." >&2
-                printf '\nif [ -e %s ]; then . %s; fi # added by Nix installer\n' "$p" "$p" >> "$fn"
+                printf '\nif [ -e %s ]; then . %s; fi # added by Nix installer\n' "$p_sh" "$p_sh" >> "$fn"
             fi
             added=1
+            p=${p_sh}
             break
         fi
     done
+
+    if [ -d "$HOME/.config/fish" ]; then
+        fishdir=$HOME/.config/fish/conf.d
+        if [ ! -d "$fishdir" ]; then
+            mkdir -p "$fishdir"
+        fi
+
+        fn="$fishdir/nix.fish"
+        echo "placing $fn..." >&2
+        printf '\nif test -e %s; . %s; end # added by Nix installer\n' "$p_fish" "$p_fish" > "$fn"
+        added=1
+        p=${p_fish}
+    fi
+else
+    p=${p_sh}
 fi
 
 if [ -z "$added" ]; then

scripts/install.in

@@ -40,12 +40,12 @@ case "$(uname -s).$(uname -m)" in
         path=@tarballPath_aarch64-linux@
         system=aarch64-linux
         ;;
-    Linux.armv6l_linux)
+    Linux.armv6l)
         hash=@tarballHash_armv6l-linux@
         path=@tarballPath_armv6l-linux@
         system=armv6l-linux
         ;;
-    Linux.armv7l_linux)
+    Linux.armv7l)
         hash=@tarballHash_armv7l-linux@
         path=@tarballPath_armv7l-linux@
         system=armv7l-linux

scripts/local.mk

@@ -6,6 +6,8 @@ noinst-scripts += $(nix_noinst_scripts)
 profiledir = $(sysconfdir)/profile.d
 
 $(eval $(call install-file-as, $(d)/nix-profile.sh, $(profiledir)/nix.sh, 0644))
+$(eval $(call install-file-as, $(d)/nix-profile.fish, $(profiledir)/nix.fish, 0644))
 $(eval $(call install-file-as, $(d)/nix-profile-daemon.sh, $(profiledir)/nix-daemon.sh, 0644))
+$(eval $(call install-file-as, $(d)/nix-profile-daemon.fish, $(profiledir)/nix-daemon.fish, 0644))
 
 clean-files += $(nix_noinst_scripts)

scripts/nix-profile-daemon.fish.in

@@ -0,0 +1,49 @@
+function add_path --argument-names new_path
+    if type -q fish_add_path
+        # fish 3.2.0 or newer
+	fish_add_path --prepend --global $new_path
+    else
+        # older versions of fish
+        if not contains $new_path $fish_user_paths
+            set --global fish_user_paths $new_path $fish_user_paths
+        end
+    end
+end
+
+# Only execute this file once per shell.
+if test -n "$__ETC_PROFILE_NIX_SOURCED"
+  exit
+end
+
+set __ETC_PROFILE_NIX_SOURCED 1
+
+set --export NIX_PROFILES "@localstatedir@/nix/profiles/default $HOME/.nix-profile"
+
+# Set $NIX_SSL_CERT_FILE so that Nixpkgs applications like curl work.
+if test -n "$NIX_SSH_CERT_FILE"
+  : # Allow users to override the NIX_SSL_CERT_FILE
+else if test -e /etc/ssl/certs/ca-certificates.crt # NixOS, Ubuntu, Debian, Gentoo, Arch
+  set --export NIX_SSL_CERT_FILE /etc/ssl/certs/ca-certificates.crt
+else if test -e /etc/ssl/ca-bundle.pem # openSUSE Tumbleweed
+  set --export NIX_SSL_CERT_FILE /etc/ssl/ca-bundle.pem
+else if test -e /etc/ssl/certs/ca-bundle.crt # Old NixOS
+  set --export NIX_SSL_CERT_FILE /etc/ssl/certs/ca-bundle.crt
+else if test -e /etc/pki/tls/certs/ca-bundle.crt # Fedora, CentOS
+  set --export NIX_SSL_CERT_FILE /etc/pki/tls/certs/ca-bundle.crt
+else if test -e "$NIX_LINK/etc/ssl/certs/ca-bundle.crt" # fall back to cacert in Nix profile
+  set --export NIX_SSL_CERT_FILE "$NIX_LINK/etc/ssl/certs/ca-bundle.crt"
+else if test -e "$NIX_LINK/etc/ca-bundle.crt" # old cacert in Nix profile
+  set --export NIX_SSL_CERT_FILE "$NIX_LINK/etc/ca-bundle.crt"
+else
+  # Fall back to what is in the nix profiles, favouring whatever is defined last.
+  for i in $NIX_PROFILES
+    if test -e "$i/etc/ssl/certs/ca-bundle.crt"
+      set --export NIX_SSL_CERT_FILE "$i/etc/ssl/certs/ca-bundle.crt"
+    end
+  end
+end
+
+add_path "@localstatedir@/nix/profiles/default/bin"
+add_path "$HOME/.nix-profile/bin"
+
+functions -e add_path

scripts/nix-profile.fish.in

@@ -0,0 +1,51 @@
+function add_path --argument-names new_path
+    if type -q fish_add_path
+        # fish 3.2.0 or newer
+	fish_add_path --prepend --global $new_path
+    else
+        # older versions of fish
+        if not contains $new_path $fish_user_paths
+            set --global fish_user_paths $new_path $fish_user_paths
+        end
+    end
+end
+
+if test -n "$HOME" && test -n "$USER"
+
+    # Set up the per-user profile.
+
+    set NIX_LINK $HOME/.nix-profile
+
+    # Set up environment.
+    # This part should be kept in sync with nixpkgs:nixos/modules/programs/environment.nix
+    set --export NIX_PROFILES "@localstatedir@/nix/profiles/default $HOME/.nix-profile"
+
+    # Set $NIX_SSL_CERT_FILE so that Nixpkgs applications like curl work.
+    if test -n "$NIX_SSH_CERT_FILE"
+        : # Allow users to override the NIX_SSL_CERT_FILE
+    else if test -e /etc/ssl/certs/ca-certificates.crt # NixOS, Ubuntu, Debian, Gentoo, Arch
+        set --export NIX_SSL_CERT_FILE /etc/ssl/certs/ca-certificates.crt
+    else if test -e /etc/ssl/ca-bundle.pem # openSUSE Tumbleweed
+        set --export NIX_SSL_CERT_FILE /etc/ssl/ca-bundle.pem
+    else if test -e /etc/ssl/certs/ca-bundle.crt # Old NixOS
+        set --export NIX_SSL_CERT_FILE /etc/ssl/certs/ca-bundle.crt
+    else if test -e /etc/pki/tls/certs/ca-bundle.crt # Fedora, CentOS
+        set --export NIX_SSL_CERT_FILE /etc/pki/tls/certs/ca-bundle.crt
+    else if test -e "$NIX_LINK/etc/ssl/certs/ca-bundle.crt" # fall back to cacert in Nix profile
+        set --export NIX_SSL_CERT_FILE "$NIX_LINK/etc/ssl/certs/ca-bundle.crt"
+    else if test -e "$NIX_LINK/etc/ca-bundle.crt" # old cacert in Nix profile
+        set --export NIX_SSL_CERT_FILE "$NIX_LINK/etc/ca-bundle.crt"
+    end
+
+    # Only use MANPATH if it is already set. In general `man` will just simply
+    # pick up `.nix-profile/share/man` because is it close to `.nix-profile/bin`
+    # which is in the $PATH. For more info, run `manpath -d`.
+    if set --query MANPATH
+      set --export --prepend --path MANPATH "$NIX_LINK/share/man"
+    end
+
+    add_path "$NIX_LINK/bin"
+    set --erase NIX_LINK
+end
+
+functions -e add_path

scripts/nix-profile.sh.in

@@ -1,7 +1,6 @@
 if [ -n "$HOME" ] && [ -n "$USER" ]; then
 
     # Set up the per-user profile.
-    # This part should be kept in sync with nixpkgs:nixos/modules/programs/shell.nix
 
     NIX_LINK=$HOME/.nix-profile
 

src/build-remote/build-remote.cc

@@ -186,12 +186,12 @@ static int main_build_remote(int argc, char * * argv)
                         // build the hint template.
                         std::string errorText =
                             "Failed to find a machine for remote build!\n"
-                            "derivation: %s\nrequired (system, features): (%s, %s)";
+                            "derivation: %s\nrequired (system, features): (%s, [%s])";
                         errorText += "\n%s available machines:";
                         errorText += "\n(systems, maxjobs, supportedFeatures, mandatoryFeatures)";
 
                         for (unsigned int i = 0; i < machines.size(); ++i)
-                            errorText += "\n(%s, %s, %s, %s)";
+                            errorText += "\n([%s], %s, [%s], [%s])";
 
                         // add the template values.
                         std::string drvstr;

src/libcmd/command.cc

@@ -88,7 +88,8 @@ EvalCommand::EvalCommand()
 {
     addFlag({
         .longName = "debugger",
-        .description = "start an interactive environment if evaluation fails",
+        .description = "Start an interactive environment if evaluation fails.",
+        .category = MixEvalArgs::category,
         .handler = {&startReplOnEvalErrors, true},
     });
 }
@@ -225,7 +226,7 @@ MixProfile::MixProfile()
 {
     addFlag({
         .longName = "profile",
-        .description = "The profile to update.",
+        .description = "The profile to operate on.",
         .labels = {"path"},
         .handler = {&profile},
         .completer = completePath

src/libcmd/command.hh

@@ -78,10 +78,16 @@ struct MixFlakeOptions : virtual Args, EvalCommand
 {
     flake::LockFlags lockFlags;
 
+    std::optional<std::string> needsFlakeInputCompletion = {};
+
     MixFlakeOptions();
 
-    virtual std::optional<FlakeRef> getFlakeRefForCompletion()
+    virtual std::vector<std::string> getFlakesForCompletion()
     { return {}; }
+
+    void completeFlakeInput(std::string_view prefix);
+
+    void completionHook() override;
 };
 
 struct SourceExprCommand : virtual Args, MixFlakeOptions
@@ -121,7 +127,7 @@ struct InstallablesCommand : virtual Args, SourceExprCommand
 
     virtual bool useDefaultInstallables() { return true; }
 
-    std::optional<FlakeRef> getFlakeRefForCompletion() override;
+    std::vector<std::string> getFlakesForCompletion() override;
 
 protected:
 
@@ -137,9 +143,9 @@ struct InstallableCommand : virtual Args, SourceExprCommand
 
     void prepare() override;
 
-    std::optional<FlakeRef> getFlakeRefForCompletion() override
+    std::vector<std::string> getFlakesForCompletion() override
     {
-        return parseFlakeRefWithFragment(_installable, absPath(".")).first;
+        return {_installable};
     }
 
 private:

src/libcmd/common-eval-args.cc

@@ -13,8 +13,6 @@ namespace nix {
 
 MixEvalArgs::MixEvalArgs()
 {
-    auto category = "Common evaluation options";
-
     addFlag({
         .longName = "arg",
         .description = "Pass the value *expr* as the argument *name* to Nix functions.",
@@ -34,7 +32,77 @@ MixEvalArgs::MixEvalArgs()
     addFlag({
         .longName = "include",
         .shortName = 'I',
-        .description = "Add *path* to the list of locations used to look up `<...>` file names.",
+        .description = R"(
+  Add *path* to the Nix search path. The Nix search path is
+  initialized from the colon-separated [`NIX_PATH`](@docroot@/command-ref/env-common.md#env-NIX_PATH) environment
+  variable, and is used to look up the location of Nix expressions using [paths](@docroot@/language/values.md#type-path) enclosed in angle
+  brackets (i.e., `<nixpkgs>`).
+
+  For instance, passing
+
+  ```
+  -I /home/eelco/Dev
+  -I /etc/nixos
+  ```
+
+  will cause Nix to look for paths relative to `/home/eelco/Dev` and
+  `/etc/nixos`, in that order. This is equivalent to setting the
+  `NIX_PATH` environment variable to
+
+  ```
+  /home/eelco/Dev:/etc/nixos
+  ```
+
+  It is also possible to match paths against a prefix. For example,
+  passing
+
+  ```
+  -I nixpkgs=/home/eelco/Dev/nixpkgs-branch
+  -I /etc/nixos
+  ```
+
+  will cause Nix to search for `<nixpkgs/path>` in
+  `/home/eelco/Dev/nixpkgs-branch/path` and `/etc/nixos/nixpkgs/path`.
+
+  If a path in the Nix search path starts with `http://` or `https://`,
+  it is interpreted as the URL of a tarball that will be downloaded and
+  unpacked to a temporary location. The tarball must consist of a single
+  top-level directory. For example, passing
+
+  ```
+  -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/master.tar.gz
+  ```
+
+  tells Nix to download and use the current contents of the `master`
+  branch in the `nixpkgs` repository.
+
+  The URLs of the tarballs from the official `nixos.org` channels
+  (see [the manual page for `nix-channel`](../nix-channel.md)) can be
+  abbreviated as `channel:<channel-name>`.  For instance, the
+  following two flags are equivalent:
+
+  ```
+  -I nixpkgs=channel:nixos-21.05
+  -I nixpkgs=https://nixos.org/channels/nixos-21.05/nixexprs.tar.xz
+  ```
+
+  You can also fetch source trees using [flake URLs](./nix3-flake.md#url-like-syntax) and add them to the
+  search path. For instance,
+
+  ```
+  -I nixpkgs=flake:nixpkgs
+  ```
+
+  specifies that the prefix `nixpkgs` shall refer to the source tree
+  downloaded from the `nixpkgs` entry in the flake registry. Similarly,
+
+  ```
+  -I nixpkgs=flake:github:NixOS/nixpkgs/nixos-22.05
+  ```
+
+  makes `<nixpkgs>` refer to a particular branch of the
+  `NixOS/nixpkgs` repository on GitHub.
+  )",
         .category = category,
         .labels = {"path"},
         .handler = {[&](std::string s) { searchPath.push_back(s); }}
@@ -91,14 +159,25 @@ Bindings * MixEvalArgs::getAutoArgs(EvalState & state)
 
 Path lookupFileArg(EvalState & state, std::string_view s)
 {
-    if (isUri(s)) {
-        return state.store->toRealPath(
-            fetchers::downloadTarball(
-                state.store, resolveUri(s), "source", false).first.storePath);
-    } else if (s.size() > 2 && s.at(0) == '<' && s.at(s.size() - 1) == '>') {
+    if (EvalSettings::isPseudoUrl(s)) {
+        auto storePath = fetchers::downloadTarball(
+            state.store, EvalSettings::resolvePseudoUrl(s), "source", false).first.storePath;
+        return state.store->toRealPath(storePath);
+    }
+
+    else if (hasPrefix(s, "flake:")) {
+        settings.requireExperimentalFeature(Xp::Flakes);
+        auto flakeRef = parseFlakeRef(std::string(s.substr(6)), {}, true, false);
+        auto storePath = flakeRef.resolve(state.store).fetchTree(state.store).first.storePath;
+        return state.store->toRealPath(storePath);
+    }
+
+    else if (s.size() > 2 && s.at(0) == '<' && s.at(s.size() - 1) == '>') {
         Path p(s.substr(1, s.size() - 2));
         return state.findFile(p);
-    } else
+    }
+
+    else
         return absPath(std::string(s));
 }
 

src/libcmd/common-eval-args.hh

@@ -10,6 +10,8 @@ class Bindings;
 
 struct MixEvalArgs : virtual Args
 {
+    static constexpr auto category = "Common evaluation options";
+
     MixEvalArgs();
 
     Bindings * getAutoArgs(EvalState & state);

src/libcmd/installables.cc

@@ -1,5 +1,6 @@
 #include "globals.hh"
 #include "installables.hh"
+#include "outputs-spec.hh"
 #include "util.hh"
 #include "command.hh"
 #include "attr-path.hh"
@@ -23,17 +24,6 @@
 
 namespace nix {
 
-void completeFlakeInputPath(
-    ref<EvalState> evalState,
-    const FlakeRef & flakeRef,
-    std::string_view prefix)
-{
-    auto flake = flake::getFlake(*evalState, flakeRef, true);
-    for (auto & input : flake.inputs)
-        if (hasPrefix(input.first, prefix))
-            completions->add(input.first);
-}
-
 MixFlakeOptions::MixFlakeOptions()
 {
     auto category = "Common flake-related options";
@@ -86,8 +76,7 @@ MixFlakeOptions::MixFlakeOptions()
             lockFlags.inputUpdates.insert(flake::parseInputPath(s));
         }},
         .completer = {[&](size_t, std::string_view prefix) {
-            if (auto flakeRef = getFlakeRefForCompletion())
-                completeFlakeInputPath(getEvalState(), *flakeRef, prefix);
+            needsFlakeInputCompletion = {std::string(prefix)};
         }}
     });
 
@@ -103,12 +92,10 @@ MixFlakeOptions::MixFlakeOptions()
                 parseFlakeRef(flakeRef, absPath("."), true));
         }},
         .completer = {[&](size_t n, std::string_view prefix) {
-            if (n == 0) {
-                if (auto flakeRef = getFlakeRefForCompletion())
-                    completeFlakeInputPath(getEvalState(), *flakeRef, prefix);
-            } else if (n == 1) {
+            if (n == 0)
+                needsFlakeInputCompletion = {std::string(prefix)};
+            else if (n == 1)
                 completeFlakeRef(getEvalState()->store, prefix);
-            }
         }}
     });
 
@@ -139,6 +126,24 @@ MixFlakeOptions::MixFlakeOptions()
     });
 }
 
+void MixFlakeOptions::completeFlakeInput(std::string_view prefix)
+{
+    auto evalState = getEvalState();
+    for (auto & flakeRefS : getFlakesForCompletion()) {
+        auto flakeRef = parseFlakeRefWithFragment(expandTilde(flakeRefS), absPath(".")).first;
+        auto flake = flake::getFlake(*evalState, flakeRef, true);
+        for (auto & input : flake.inputs)
+            if (hasPrefix(input.first, prefix))
+                completions->add(input.first);
+    }
+}
+
+void MixFlakeOptions::completionHook()
+{
+    if (auto & prefix = needsFlakeInputCompletion)
+        completeFlakeInput(*prefix);
+}
+
 SourceExprCommand::SourceExprCommand(bool supportReadOnlyMode)
 {
     addFlag({
@@ -164,7 +169,7 @@ SourceExprCommand::SourceExprCommand(bool supportReadOnlyMode)
 
     addFlag({
         .longName = "derivation",
-        .description = "Operate on the store derivation rather than its outputs.",
+        .description = "Operate on the [store derivation](../../glossary.md#gloss-store-derivation) rather than its outputs.",
         .category = installablesCategory,
         .handler = {&operateOn, OperateOn::Derivation},
     });
@@ -203,55 +208,59 @@ Strings SourceExprCommand::getDefaultFlakeAttrPathPrefixes()
 
 void SourceExprCommand::completeInstallable(std::string_view prefix)
 {
-    if (file) {
-        completionType = ctAttrs;
+    try {
+        if (file) {
+            completionType = ctAttrs;
 
-        evalSettings.pureEval = false;
-        auto state = getEvalState();
-        Expr *e = state->parseExprFromFile(
-            resolveExprPath(state->checkSourcePath(lookupFileArg(*state, *file)))
-        );
+            evalSettings.pureEval = false;
+            auto state = getEvalState();
+            Expr *e = state->parseExprFromFile(
+                resolveExprPath(state->checkSourcePath(lookupFileArg(*state, *file)))
+                );
 
-        Value root;
-        state->eval(e, root);
+            Value root;
+            state->eval(e, root);
 
-        auto autoArgs = getAutoArgs(*state);
+            auto autoArgs = getAutoArgs(*state);
 
-        std::string prefix_ = std::string(prefix);
-        auto sep = prefix_.rfind('.');
-        std::string searchWord;
-        if (sep != std::string::npos) {
-            searchWord = prefix_.substr(sep + 1, std::string::npos);
-            prefix_ = prefix_.substr(0, sep);
-        } else {
-            searchWord = prefix_;
-            prefix_ = "";
-        }
+            std::string prefix_ = std::string(prefix);
+            auto sep = prefix_.rfind('.');
+            std::string searchWord;
+            if (sep != std::string::npos) {
+                searchWord = prefix_.substr(sep + 1, std::string::npos);
+                prefix_ = prefix_.substr(0, sep);
+            } else {
+                searchWord = prefix_;
+                prefix_ = "";
+            }
 
-        auto [v, pos] = findAlongAttrPath(*state, prefix_, *autoArgs, root);
-        Value &v1(*v);
-        state->forceValue(v1, pos);
-        Value v2;
-        state->autoCallFunction(*autoArgs, v1, v2);
+            auto [v, pos] = findAlongAttrPath(*state, prefix_, *autoArgs, root);
+            Value &v1(*v);
+            state->forceValue(v1, pos);
+            Value v2;
+            state->autoCallFunction(*autoArgs, v1, v2);
 
-        if (v2.type() == nAttrs) {
-            for (auto & i : *v2.attrs) {
-                std::string name = state->symbols[i.name];
-                if (name.find(searchWord) == 0) {
-                    if (prefix_ == "")
-                        completions->add(name);
-                    else
-                        completions->add(prefix_ + "." + name);
+            if (v2.type() == nAttrs) {
+                for (auto & i : *v2.attrs) {
+                    std::string name = state->symbols[i.name];
+                    if (name.find(searchWord) == 0) {
+                        if (prefix_ == "")
+                            completions->add(name);
+                        else
+                            completions->add(prefix_ + "." + name);
+                    }
                 }
             }
+        } else {
+            completeFlakeRefWithFragment(
+                getEvalState(),
+                lockFlags,
+                getDefaultFlakeAttrPathPrefixes(),
+                getDefaultFlakeAttrPaths(),
+                prefix);
         }
-    } else {
-        completeFlakeRefWithFragment(
-            getEvalState(),
-            lockFlags,
-            getDefaultFlakeAttrPathPrefixes(),
-            getDefaultFlakeAttrPaths(),
-            prefix);
+    } catch (EvalError&) {
+        // Don't want eval errors to mess-up with the completion engine, so let's just swallow them
     }
 }
 
@@ -350,7 +359,7 @@ void completeFlakeRef(ref<Store> store, std::string_view prefix)
     }
 }
 
-DerivedPath Installable::toDerivedPath()
+DerivedPathWithInfo Installable::toDerivedPath()
 {
     auto buildables = toDerivedPaths();
     if (buildables.size() != 1)
@@ -391,93 +400,53 @@ static StorePath getDeriver(
 struct InstallableStorePath : Installable
 {
     ref<Store> store;
-    StorePath storePath;
+    DerivedPath req;
 
-    InstallableStorePath(ref<Store> store, StorePath && storePath)
-        : store(store), storePath(std::move(storePath)) { }
+    InstallableStorePath(ref<Store> store, DerivedPath && req)
+        : store(store), req(std::move(req))
+    { }
 
-    std::string what() const override { return store->printStorePath(storePath); }
-
-    DerivedPaths toDerivedPaths() override
+    std::string what() const override
     {
-        if (storePath.isDerivation()) {
-            auto drv = store->readDerivation(storePath);
-            return {
-                DerivedPath::Built {
-                    .drvPath = storePath,
-                    .outputs = drv.outputNames(),
-                }
-            };
-        } else {
-            return {
-                DerivedPath::Opaque {
-                    .path = storePath,
-                }
-            };
-        }
+        return req.to_string(*store);
     }
 
-    StorePathSet toDrvPaths(ref<Store> store) override
+    DerivedPathsWithInfo toDerivedPaths() override
     {
-        if (storePath.isDerivation()) {
-            return {storePath};
-        } else {
-            return {getDeriver(store, *this, storePath)};
-        }
+        return {{.path = req, .info = {} }};
     }
 
     std::optional<StorePath> getStorePath() override
     {
-        return storePath;
+        return std::visit(overloaded {
+            [&](const DerivedPath::Built & bfd) {
+                return bfd.drvPath;
+            },
+            [&](const DerivedPath::Opaque & bo) {
+                return bo.path;
+            },
+        }, req.raw());
     }
 };
 
-DerivedPaths InstallableValue::toDerivedPaths()
-{
-    DerivedPaths res;
-
-    std::map<StorePath, std::set<std::string>> drvsToOutputs;
-    RealisedPath::Set drvsToCopy;
-
-    // Group by derivation, helps with .all in particular
-    for (auto & drv : toDerivations()) {
-        for (auto & outputName : drv.outputsToInstall)
-            drvsToOutputs[drv.drvPath].insert(outputName);
-        drvsToCopy.insert(drv.drvPath);
-    }
-
-    for (auto & i : drvsToOutputs)
-        res.push_back(DerivedPath::Built { i.first, i.second });
-
-    return res;
-}
-
-StorePathSet InstallableValue::toDrvPaths(ref<Store> store)
-{
-    StorePathSet res;
-    for (auto & drv : toDerivations())
-        res.insert(drv.drvPath);
-    return res;
-}
-
 struct InstallableAttrPath : InstallableValue
 {
     SourceExprCommand & cmd;
     RootValue v;
     std::string attrPath;
-    OutputsSpec outputsSpec;
+    ExtendedOutputsSpec extendedOutputsSpec;
 
     InstallableAttrPath(
         ref<EvalState> state,
         SourceExprCommand & cmd,
         Value * v,
         const std::string & attrPath,
-        OutputsSpec outputsSpec)
+        ExtendedOutputsSpec extendedOutputsSpec)
         : InstallableValue(state)
         , cmd(cmd)
         , v(allocRootValue(v))
         , attrPath(attrPath)
-        , outputsSpec(std::move(outputsSpec))
+        , extendedOutputsSpec(std::move(extendedOutputsSpec))
     { }
 
     std::string what() const override { return attrPath; }
@@ -489,40 +458,54 @@ struct InstallableAttrPath : InstallableValue
         return {vRes, pos};
     }
 
-    virtual std::vector<InstallableValue::DerivationInfo> toDerivations() override;
-};
+    DerivedPathsWithInfo toDerivedPaths() override
+    {
+        auto v = toValue(*state).first;
 
-std::vector<InstallableValue::DerivationInfo> InstallableAttrPath::toDerivations()
-{
-    auto v = toValue(*state).first;
+        Bindings & autoArgs = *cmd.getAutoArgs(*state);
 
-    Bindings & autoArgs = *cmd.getAutoArgs(*state);
+        DrvInfos drvInfos;
+        getDerivations(*state, *v, "", autoArgs, drvInfos, false);
 
-    DrvInfos drvInfos;
-    getDerivations(*state, *v, "", autoArgs, drvInfos, false);
+        // Backward compatibility hack: group results by drvPath. This
+        // helps keep .all output together.
+        std::map<StorePath, OutputsSpec> byDrvPath;
 
-    std::vector<DerivationInfo> res;
-    for (auto & drvInfo : drvInfos) {
-        auto drvPath = drvInfo.queryDrvPath();
-        if (!drvPath)
-            throw Error("'%s' is not a derivation", what());
+        for (auto & drvInfo : drvInfos) {
+            auto drvPath = drvInfo.queryDrvPath();
+            if (!drvPath)
+                throw Error("'%s' is not a derivation", what());
 
-        std::set<std::string> outputsToInstall;
+            auto newOutputs = std::visit(overloaded {
+                [&](const ExtendedOutputsSpec::Default & d) -> OutputsSpec {
+                    std::set<std::string> outputsToInstall;
+                    for (auto & output : drvInfo.queryOutputs(false, true))
+                        outputsToInstall.insert(output.first);
+                    return OutputsSpec::Names { std::move(outputsToInstall) };
+                },
+                [&](const ExtendedOutputsSpec::Explicit & e) -> OutputsSpec {
+                    return e;
+                },
+            }, extendedOutputsSpec.raw());
 
-        if (auto outputNames = std::get_if<OutputNames>(&outputsSpec))
-            outputsToInstall = *outputNames;
-        else
-            for (auto & output : drvInfo.queryOutputs(false, std::get_if<DefaultOutputs>(&outputsSpec)))
-                outputsToInstall.insert(output.first);
+            auto [iter, didInsert] = byDrvPath.emplace(*drvPath, newOutputs);
 
-        res.push_back(DerivationInfo {
-            .drvPath = *drvPath,
-            .outputsToInstall = std::move(outputsToInstall)
-        });
+            if (!didInsert)
+                iter->second = iter->second.union_(newOutputs);
+        }
+
+        DerivedPathsWithInfo res;
+        for (auto & [drvPath, outputs] : byDrvPath)
+            res.push_back({
+                .path = DerivedPath::Built {
+                    .drvPath = drvPath,
+                    .outputs = outputs,
+                },
+            });
+
+        return res;
     }
-
-    return res;
-}
+};
 
 std::vector<std::string> InstallableFlake::getActualAttrPaths()
 {
@@ -595,7 +578,7 @@ InstallableFlake::InstallableFlake(
     ref<EvalState> state,
     FlakeRef && flakeRef,
     std::string_view fragment,
-    OutputsSpec outputsSpec,
+    ExtendedOutputsSpec extendedOutputsSpec,
     Strings attrPaths,
     Strings prefixes,
     const flake::LockFlags & lockFlags)
@@ -603,69 +586,99 @@ InstallableFlake::InstallableFlake(
       flakeRef(flakeRef),
       attrPaths(fragment == "" ? attrPaths : Strings{(std::string) fragment}),
       prefixes(fragment == "" ? Strings{} : prefixes),
-      outputsSpec(std::move(outputsSpec)),
+      extendedOutputsSpec(std::move(extendedOutputsSpec)),
       lockFlags(lockFlags)
 {
     if (cmd && cmd->getAutoArgs(*state)->size())
         throw UsageError("'--arg' and '--argstr' are incompatible with flakes");
 }
 
-std::tuple<std::string, FlakeRef, InstallableValue::DerivationInfo> InstallableFlake::toDerivation()
+DerivedPathsWithInfo InstallableFlake::toDerivedPaths()
 {
+    Activity act(*logger, lvlTalkative, actUnknown, fmt("evaluating derivation '%s'", what()));
+
     auto attr = getCursor(*state);
 
     auto attrPath = attr->getAttrPathStr();
 
-    if (!attr->isDerivation())
-        throw Error("flake output attribute '%s' is not a derivation", attrPath);
+    if (!attr->isDerivation()) {
+
+        // FIXME: use eval cache?
+        auto v = attr->forceValue();
+
+        if (v.type() == nPath) {
+            PathSet context;
+            auto storePath = state->copyPathToStore(context, Path(v.path));
+            return {{
+                .path = DerivedPath::Opaque {
+                    .path = std::move(storePath),
+                }
+            }};
+        }
+
+        else if (v.type() == nString) {
+            PathSet context;
+            auto s = state->forceString(v, context, noPos);
+            auto storePath = state->store->maybeParseStorePath(s);
+            if (storePath && context.count(std::string(s))) {
+                return {{
+                    .path = DerivedPath::Opaque {
+                        .path = std::move(*storePath),
+                    }
+                }};
+            } else
+                throw Error("flake output attribute '%s' evaluates to the string '%s' which is not a store path", attrPath, s);
+        }
+
+        else
+            throw Error("flake output attribute '%s' is not a derivation or path", attrPath);
+    }
 
     auto drvPath = attr->forceDerivation();
 
-    std::set<std::string> outputsToInstall;
     std::optional<NixInt> priority;
 
-    if (auto aOutputSpecified = attr->maybeGetAttr(state->sOutputSpecified)) {
-        if (aOutputSpecified->getBool()) {
-            if (auto aOutputName = attr->maybeGetAttr("outputName"))
-                outputsToInstall = { aOutputName->getString() };
-        }
-    }
-
-    else if (auto aMeta = attr->maybeGetAttr(state->sMeta)) {
-        if (auto aOutputsToInstall = aMeta->maybeGetAttr("outputsToInstall"))
-            for (auto & s : aOutputsToInstall->getListOfStrings())
-                outputsToInstall.insert(s);
+    if (attr->maybeGetAttr(state->sOutputSpecified)) {
+    } else if (auto aMeta = attr->maybeGetAttr(state->sMeta)) {
         if (auto aPriority = aMeta->maybeGetAttr("priority"))
             priority = aPriority->getInt();
     }
 
-    if (outputsToInstall.empty() || std::get_if<AllOutputs>(&outputsSpec)) {
-        outputsToInstall.clear();
-        if (auto aOutputs = attr->maybeGetAttr(state->sOutputs))
-            for (auto & s : aOutputs->getListOfStrings())
-                outputsToInstall.insert(s);
-    }
+    return {{
+        .path = DerivedPath::Built {
+            .drvPath = std::move(drvPath),
+            .outputs = std::visit(overloaded {
+                [&](const ExtendedOutputsSpec::Default & d) -> OutputsSpec {
+                    std::set<std::string> outputsToInstall;
+                    if (auto aOutputSpecified = attr->maybeGetAttr(state->sOutputSpecified)) {
+                        if (aOutputSpecified->getBool()) {
+                            if (auto aOutputName = attr->maybeGetAttr("outputName"))
+                                outputsToInstall = { aOutputName->getString() };
+                        }
+                    } else if (auto aMeta = attr->maybeGetAttr(state->sMeta)) {
+                        if (auto aOutputsToInstall = aMeta->maybeGetAttr("outputsToInstall"))
+                            for (auto & s : aOutputsToInstall->getListOfStrings())
+                                outputsToInstall.insert(s);
+                    }
 
-    if (outputsToInstall.empty())
-        outputsToInstall.insert("out");
+                    if (outputsToInstall.empty())
+                        outputsToInstall.insert("out");
 
-    if (auto outputNames = std::get_if<OutputNames>(&outputsSpec))
-        outputsToInstall = *outputNames;
-
-    auto drvInfo = DerivationInfo {
-        .drvPath = std::move(drvPath),
-        .outputsToInstall = std::move(outputsToInstall),
-        .priority = priority,
-    };
-
-    return {attrPath, getLockedFlake()->flake.lockedRef, std::move(drvInfo)};
-}
-
-std::vector<InstallableValue::DerivationInfo> InstallableFlake::toDerivations()
-{
-    std::vector<DerivationInfo> res;
-    res.push_back(std::get<2>(toDerivation()));
-    return res;
+                    return OutputsSpec::Names { std::move(outputsToInstall) };
+                },
+                [&](const ExtendedOutputsSpec::Explicit & e) -> OutputsSpec {
+                    return e;
+                },
+            }, extendedOutputsSpec.raw()),
+        },
+        .info = {
+            .priority = priority,
+            .originalRef = flakeRef,
+            .resolvedRef = getLockedFlake()->flake.lockedRef,
+            .attrPath = attrPath,
+            .extendedOutputsSpec = extendedOutputsSpec,
+        }
+    }};
 }
 
 std::pair<Value *, PosIdx> InstallableFlake::toValue(EvalState & state)
@@ -771,7 +784,8 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
         if (file == "-") {
             auto e = state->parseStdin();
             state->eval(e, *vFile);
-        } else if (file)
+        }
+        else if (file)
             state->evalFile(lookupFileArg(*state, *file), *vFile);
         else {
             auto e = state->parseExprFromString(*expr, absPath("."));
@@ -779,12 +793,12 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
         }
 
         for (auto & s : ss) {
-            auto [prefix, outputsSpec] = parseOutputsSpec(s);
+            auto [prefix, extendedOutputsSpec] = ExtendedOutputsSpec::parse(s);
             result.push_back(
                 std::make_shared<InstallableAttrPath>(
                     state, *this, vFile,
-                    prefix == "." ? "" : prefix,
-                    outputsSpec));
+                    prefix == "." ? "" : std::string { prefix },
+                    extendedOutputsSpec));
         }
 
     } else {
@@ -792,9 +806,46 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
         for (auto & s : ss) {
             std::exception_ptr ex;
 
-            if (s.find('/') != std::string::npos) {
+            auto [prefix_, extendedOutputsSpec_] = ExtendedOutputsSpec::parse(s);
+            // To avoid clang's pedantry
+            auto prefix = std::move(prefix_);
+            auto extendedOutputsSpec = std::move(extendedOutputsSpec_);
+
+            auto found = prefix.find('/');
+            if (found != std::string::npos) {
                 try {
-                    result.push_back(std::make_shared<InstallableStorePath>(store, store->followLinksToStorePath(s)));
+                    auto derivedPath = std::visit(overloaded {
+                        // If the user did not use ^, we treat the output more liberally.
+                        [&](const ExtendedOutputsSpec::Default &) -> DerivedPath {
+                            // First, we accept a symlink chain or an actual store path.
+                            auto storePath = store->followLinksToStorePath(prefix);
+                            // Second, we see if the store path ends in `.drv` to decide what sort
+                            // of derived path they want.
+                            //
+                            // This handling predates the `^` syntax. The `^*` in
+                            // `/nix/store/hash-foo.drv^*` unambiguously means "do the
+                            // `DerivedPath::Built` case", so plain `/nix/store/hash-foo.drv` could
+                            // also unambiguously mean "do the DerivedPath::Opaque` case".
+                            //
+                            // Issue #7261 tracks reconsidering this `.drv` dispatching.
+                            return storePath.isDerivation()
+                                ? (DerivedPath) DerivedPath::Built {
+                                    .drvPath = std::move(storePath),
+                                    .outputs = OutputsSpec::All {},
+                                }
+                                : (DerivedPath) DerivedPath::Opaque {
+                                    .path = std::move(storePath),
+                                };
+                        },
+                        // If the user did use ^, we just do exactly what is written.
+                        [&](const ExtendedOutputsSpec::Explicit & outputSpec) -> DerivedPath {
+                            return DerivedPath::Built {
+                                .drvPath = store->parseStorePath(prefix),
+                                .outputs = outputSpec,
+                            };
+                        },
+                    }, extendedOutputsSpec.raw());
+                    result.push_back(std::make_shared<InstallableStorePath>(store, std::move(derivedPath)));
                     continue;
                 } catch (BadStorePath &) {
                 } catch (...) {
@@ -804,13 +855,13 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
             }
 
             try {
-                auto [flakeRef, fragment, outputsSpec] = parseFlakeRefWithFragmentAndOutputsSpec(s, absPath("."));
+                auto [flakeRef, fragment] = parseFlakeRefWithFragment(std::string { prefix }, absPath("."));
                 result.push_back(std::make_shared<InstallableFlake>(
                         this,
                         getEvalState(),
                         std::move(flakeRef),
                         fragment,
-                        outputsSpec,
+                        extendedOutputsSpec,
                         getDefaultFlakeAttrPaths(),
                         getDefaultFlakeAttrPathPrefixes(),
                         lockFlags));
@@ -834,20 +885,20 @@ std::shared_ptr<Installable> SourceExprCommand::parseInstallable(
     return installables.front();
 }
 
-BuiltPaths Installable::build(
+std::vector<BuiltPathWithResult> Installable::build(
     ref<Store> evalStore,
     ref<Store> store,
     Realise mode,
     const std::vector<std::shared_ptr<Installable>> & installables,
     BuildMode bMode)
 {
-    BuiltPaths res;
-    for (auto & [_, builtPath] : build2(evalStore, store, mode, installables, bMode))
-        res.push_back(builtPath);
+    std::vector<BuiltPathWithResult> res;
+    for (auto & [_, builtPathWithResult] : build2(evalStore, store, mode, installables, bMode))
+        res.push_back(builtPathWithResult);
     return res;
 }
 
-std::vector<std::pair<std::shared_ptr<Installable>, BuiltPath>> Installable::build2(
+std::vector<std::pair<std::shared_ptr<Installable>, BuiltPathWithResult>> Installable::build2(
     ref<Store> evalStore,
     ref<Store> store,
     Realise mode,
@@ -857,17 +908,23 @@ std::vector<std::pair<std::shared_ptr<Installable>, BuiltPath>> Installable::bui
     if (mode == Realise::Nothing)
         settings.readOnlyMode = true;
 
+    struct Aux
+    {
+        ExtraPathInfo info;
+        std::shared_ptr<Installable> installable;
+    };
+
     std::vector<DerivedPath> pathsToBuild;
-    std::map<DerivedPath, std::vector<std::shared_ptr<Installable>>> backmap;
+    std::map<DerivedPath, std::vector<Aux>> backmap;
 
     for (auto & i : installables) {
         for (auto b : i->toDerivedPaths()) {
-            pathsToBuild.push_back(b);
-            backmap[b].push_back(i);
+            pathsToBuild.push_back(b.path);
+            backmap[b.path].push_back({.info = b.info, .installable = i});
         }
     }
 
-    std::vector<std::pair<std::shared_ptr<Installable>, BuiltPath>> res;
+    std::vector<std::pair<std::shared_ptr<Installable>, BuiltPathWithResult>> res;
 
     switch (mode) {
 
@@ -876,42 +933,18 @@ std::vector<std::pair<std::shared_ptr<Installable>, BuiltPath>> Installable::bui
         printMissing(store, pathsToBuild, lvlError);
 
         for (auto & path : pathsToBuild) {
-            for (auto & installable : backmap[path]) {
+            for (auto & aux : backmap[path]) {
                 std::visit(overloaded {
                     [&](const DerivedPath::Built & bfd) {
-                        OutputPathMap outputs;
-                        auto drv = evalStore->readDerivation(bfd.drvPath);
-                        auto outputHashes = staticOutputHashes(*evalStore, drv); // FIXME: expensive
-                        auto drvOutputs = drv.outputsAndOptPaths(*store);
-                        for (auto & output : bfd.outputs) {
-                            auto outputHash = get(outputHashes, output);
-                            if (!outputHash)
-                                throw Error(
-                                    "the derivation '%s' doesn't have an output named '%s'",
-                                    store->printStorePath(bfd.drvPath), output);
-                            if (settings.isExperimentalFeatureEnabled(Xp::CaDerivations)) {
-                                DrvOutput outputId { *outputHash, output };
-                                auto realisation = store->queryRealisation(outputId);
-                                if (!realisation)
-                                    throw Error(
-                                        "cannot operate on an output of the "
-                                        "unbuilt derivation '%s'",
-                                        outputId.to_string());
-                                outputs.insert_or_assign(output, realisation->outPath);
-                            } else {
-                                // If ca-derivations isn't enabled, assume that
-                                // the output path is statically known.
-                                auto drvOutput = get(drvOutputs, output);
-                                assert(drvOutput);
-                                assert(drvOutput->second);
-                                outputs.insert_or_assign(
-                                    output, *drvOutput->second);
-                            }
-                        }
-                        res.push_back({installable, BuiltPath::Built { bfd.drvPath, outputs }});
+                        auto outputs = resolveDerivedPath(*store, bfd, &*evalStore);
+                        res.push_back({aux.installable, {
+                            .path = BuiltPath::Built { bfd.drvPath, outputs },
+                            .info = aux.info}});
                     },
                     [&](const DerivedPath::Opaque & bo) {
-                        res.push_back({installable, BuiltPath::Opaque { bo.path }});
+                        res.push_back({aux.installable, {
+                            .path = BuiltPath::Opaque { bo.path },
+                            .info = aux.info}});
                     },
                 }, path.raw());
             }
@@ -921,22 +954,28 @@ std::vector<std::pair<std::shared_ptr<Installable>, BuiltPath>> Installable::bui
 
     case Realise::Outputs: {
         if (settings.printMissing)
-          printMissing(store, pathsToBuild, lvlInfo);
+            printMissing(store, pathsToBuild, lvlInfo);
 
         for (auto & buildResult : store->buildPathsWithResults(pathsToBuild, bMode, evalStore)) {
             if (!buildResult.success())
                 buildResult.rethrow();
 
-            for (auto & installable : backmap[buildResult.path]) {
+            for (auto & aux : backmap[buildResult.path]) {
                 std::visit(overloaded {
                     [&](const DerivedPath::Built & bfd) {
                         std::map<std::string, StorePath> outputs;
                         for (auto & path : buildResult.builtOutputs)
                             outputs.emplace(path.first.outputName, path.second.outPath);
-                        res.push_back({installable, BuiltPath::Built { bfd.drvPath, outputs }});
+                        res.push_back({aux.installable, {
+                            .path = BuiltPath::Built { bfd.drvPath, outputs },
+                            .info = aux.info,
+                            .result = buildResult}});
                     },
                     [&](const DerivedPath::Opaque & bo) {
-                        res.push_back({installable, BuiltPath::Opaque { bo.path }});
+                        res.push_back({aux.installable, {
+                            .path = BuiltPath::Opaque { bo.path },
+                            .info = aux.info,
+                            .result = buildResult}});
                     },
                 }, buildResult.path.raw());
             }
@@ -959,9 +998,12 @@ BuiltPaths Installable::toBuiltPaths(
     OperateOn operateOn,
     const std::vector<std::shared_ptr<Installable>> & installables)
 {
-    if (operateOn == OperateOn::Output)
-        return Installable::build(evalStore, store, mode, installables);
-    else {
+    if (operateOn == OperateOn::Output) {
+        BuiltPaths res;
+        for (auto & p : Installable::build(evalStore, store, mode, installables))
+            res.push_back(p.path);
+        return res;
+    } else {
         if (mode == Realise::Nothing)
             settings.readOnlyMode = true;
 
@@ -1018,7 +1060,7 @@ StorePathSet Installable::toDerivations(
                 [&](const DerivedPath::Built & bfd) {
                     drvPaths.insert(bfd.drvPath);
                 },
-            }, b.raw());
+            }, b.path.raw());
 
     return drvPaths;
 }
@@ -1048,14 +1090,14 @@ Installables InstallablesCommand::load() {
     return parseInstallables(getStore(), _installables);
 }
 
-std::optional<FlakeRef> InstallablesCommand::getFlakeRefForCompletion()
+std::vector<std::string> InstallablesCommand::getFlakesForCompletion()
 {
     if (_installables.empty()) {
         if (useDefaultInstallables())
-            return parseFlakeRefWithFragment(".", absPath(".")).first;
+            return {"."};
         return {};
     }
-    return parseFlakeRefWithFragment(_installables.front(), absPath(".")).first;
+    return _installables;
 }
 
 InstallableCommand::InstallableCommand(bool supportReadOnlyMode)

src/libcmd/installables.hh

@@ -2,11 +2,12 @@
 
 #include "util.hh"
 #include "path.hh"
-#include "path-with-outputs.hh"
+#include "outputs-spec.hh"
 #include "derived-path.hh"
 #include "eval.hh"
 #include "store-api.hh"
 #include "flake/flake.hh"
+#include "build-result.hh"
 
 #include <optional>
 
@@ -19,7 +20,7 @@ namespace eval_cache { class EvalCache; class AttrCursor; }
 
 struct App
 {
-    std::vector<StorePathWithOutputs> context;
+    std::vector<DerivedPath> context;
     Path program;
     // FIXME: add args, sandbox settings, metadata, ...
 };
@@ -51,20 +52,42 @@ enum class OperateOn {
     Derivation
 };
 
+struct ExtraPathInfo
+{
+    std::optional<NixInt> priority;
+    std::optional<FlakeRef> originalRef;
+    std::optional<FlakeRef> resolvedRef;
+    std::optional<std::string> attrPath;
+    // FIXME: merge with DerivedPath's 'outputs' field?
+    std::optional<ExtendedOutputsSpec> extendedOutputsSpec;
+};
+
+/* A derived path with any additional info that commands might
+   need from the derivation. */
+struct DerivedPathWithInfo
+{
+    DerivedPath path;
+    ExtraPathInfo info;
+};
+
+struct BuiltPathWithResult
+{
+    BuiltPath path;
+    ExtraPathInfo info;
+    std::optional<BuildResult> result;
+};
+
+typedef std::vector<DerivedPathWithInfo> DerivedPathsWithInfo;
+
 struct Installable
 {
     virtual ~Installable() { }
 
     virtual std::string what() const = 0;
 
-    virtual DerivedPaths toDerivedPaths() = 0;
+    virtual DerivedPathsWithInfo toDerivedPaths() = 0;
 
-    virtual StorePathSet toDrvPaths(ref<Store> store)
-    {
-        throw Error("'%s' cannot be converted to a derivation path", what());
-    }
-
-    DerivedPath toDerivedPath();
+    DerivedPathWithInfo toDerivedPath();
 
     UnresolvedApp toApp(EvalState & state);
 
@@ -91,14 +114,14 @@ struct Installable
         return FlakeRef::fromAttrs({{"type","indirect"}, {"id", "nixpkgs"}});
     }
 
-    static BuiltPaths build(
+    static std::vector<BuiltPathWithResult> build(
         ref<Store> evalStore,
         ref<Store> store,
         Realise mode,
         const std::vector<std::shared_ptr<Installable>> & installables,
         BuildMode bMode = bmNormal);
 
-    static std::vector<std::pair<std::shared_ptr<Installable>, BuiltPath>> build2(
+    static std::vector<std::pair<std::shared_ptr<Installable>, BuiltPathWithResult>> build2(
         ref<Store> evalStore,
         ref<Store> store,
         Realise mode,
@@ -139,19 +162,6 @@ struct InstallableValue : Installable
     ref<EvalState> state;
 
     InstallableValue(ref<EvalState> state) : state(state) {}
-
-    struct DerivationInfo
-    {
-        StorePath drvPath;
-        std::set<std::string> outputsToInstall;
-        std::optional<NixInt> priority;
-    };
-
-    virtual std::vector<DerivationInfo> toDerivations() = 0;
-
-    DerivedPaths toDerivedPaths() override;
-
-    StorePathSet toDrvPaths(ref<Store> store) override;
 };
 
 struct InstallableFlake : InstallableValue
@@ -159,7 +169,7 @@ struct InstallableFlake : InstallableValue
     FlakeRef flakeRef;
     Strings attrPaths;
     Strings prefixes;
-    OutputsSpec outputsSpec;
+    ExtendedOutputsSpec extendedOutputsSpec;
     const flake::LockFlags & lockFlags;
     mutable std::shared_ptr<flake::LockedFlake> _lockedFlake;
 
@@ -168,7 +178,7 @@ struct InstallableFlake : InstallableValue
         ref<EvalState> state,
         FlakeRef && flakeRef,
         std::string_view fragment,
-        OutputsSpec outputsSpec,
+        ExtendedOutputsSpec extendedOutputsSpec,
         Strings attrPaths,
         Strings prefixes,
         const flake::LockFlags & lockFlags);
@@ -179,9 +189,7 @@ struct InstallableFlake : InstallableValue
 
     Value * getFlakeOutputs(EvalState & state, const flake::LockedFlake & lockedFlake);
 
-    std::tuple<std::string, FlakeRef, DerivationInfo> toDerivation();
-
-    std::vector<DerivationInfo> toDerivations() override;
+    DerivedPathsWithInfo toDerivedPaths() override;
 
     std::pair<Value *, PosIdx> toValue(EvalState & state) override;
 

src/libcmd/local.mk

@@ -8,7 +8,7 @@ libcmd_SOURCES := $(wildcard $(d)/*.cc)
 
 libcmd_CXXFLAGS += -I src/libutil -I src/libstore -I src/libexpr -I src/libmain -I src/libfetchers -I src/nix
 
-libcmd_LDFLAGS = $(EDITLINE_LIBS) -llowdown -pthread
+libcmd_LDFLAGS = $(EDITLINE_LIBS) $(LOWDOWN_LIBS) -pthread
 
 libcmd_LIBS = libstore libutil libexpr libmain libfetchers
 

src/libcmd/markdown.cc

@@ -18,7 +18,7 @@ std::string renderMarkdownToTerminal(std::string_view markdown)
         .hmargin = 0,
         .vmargin = 0,
         .feat = LOWDOWN_COMMONMARK | LOWDOWN_FENCED | LOWDOWN_DEFLIST | LOWDOWN_TABLES,
-        .oflags = 0,
+        .oflags = LOWDOWN_TERM_NOLINK,
     };
 
     auto doc = lowdown_doc_new(&opts);

src/libcmd/repl.cc

@@ -35,6 +35,7 @@ extern "C" {
 #include "finally.hh"
 #include "markdown.hh"
 #include "local-fs-store.hh"
+#include "progress-bar.hh"
 
 #if HAVE_BOEHMGC
 #define GC_INCLUDE_NEW
@@ -214,17 +215,15 @@ static std::ostream & showDebugTrace(std::ostream & out, const PosTable & positi
     out << dt.hint.str() << "\n";
 
     // prefer direct pos, but if noPos then try the expr.
-    auto pos = *dt.pos
-        ? *dt.pos
-        : positions[dt.expr.getPos() ? dt.expr.getPos() : noPos];
+    auto pos = dt.pos
+        ? dt.pos
+        : static_cast<std::shared_ptr<AbstractPos>>(positions[dt.expr.getPos() ? dt.expr.getPos() : noPos]);
 
     if (pos) {
-        printAtPos(pos, out);
-
-        auto loc = getCodeLines(pos);
-        if (loc.has_value()) {
+        out << pos;
+        if (auto loc = pos->getCodeLines()) {
             out << "\n";
-            printCodeLines(out, "", pos, *loc);
+            printCodeLines(out, "", *pos, *loc);
             out << "\n";
         }
     }
@@ -241,7 +240,11 @@ void NixRepl::mainLoop()
 
     // Allow nix-repl specific settings in .inputrc
     rl_readline_name = "nix-repl";
-    createDirs(dirOf(historyFile));
+    try {
+        createDirs(dirOf(historyFile));
+    } catch (SysError & e) {
+        logWarning(e.info());
+    }
 #ifndef READLINE
     el_hist_size = 1000;
 #endif
@@ -252,6 +255,10 @@ void NixRepl::mainLoop()
     rl_set_list_possib_func(listPossibleCallback);
 #endif
 
+    /* Stop the progress bar because it interferes with the display of
+       the repl. */
+    stopProgressBar();
+
     std::string input;
 
     while (true) {
@@ -261,6 +268,7 @@ void NixRepl::mainLoop()
             // ctrl-D should exit the debugger.
             state->debugStop = false;
             state->debugQuit = true;
+            logger->cout("");
             break;
         }
         try {
@@ -375,6 +383,10 @@ StringSet NixRepl::completePrefix(const std::string & prefix)
             i++;
         }
     } else {
+        /* Temporarily disable the debugger, to avoid re-entering readline. */
+        auto debug_repl = state->debugRepl;
+        state->debugRepl = nullptr;
+        Finally restoreDebug([&]() { state->debugRepl = debug_repl; });
         try {
             /* This is an expression that should evaluate to an
                attribute set.  Evaluate it to get the names of the
@@ -575,15 +587,17 @@ bool NixRepl::processLine(std::string line)
         Value v;
         evalString(arg, v);
 
-        const auto [file, line] = [&] () -> std::pair<std::string, uint32_t> {
+        const auto [path, line] = [&] () -> std::pair<Path, uint32_t> {
             if (v.type() == nPath || v.type() == nString) {
                 PathSet context;
-                auto filename = state->coerceToString(noPos, v, context).toOwned();
-                state->symbols.create(filename);
-                return {filename, 0};
+                auto path = state->coerceToPath(noPos, v, context);
+                return {path, 0};
             } else if (v.isLambda()) {
                 auto pos = state->positions[v.lambda.fun->pos];
-                return {pos.file, pos.line};
+                if (auto path = std::get_if<Path>(&pos.origin))
+                    return {*path, pos.line};
+                else
+                    throw Error("'%s' cannot be shown in an editor", pos);
             } else {
                 // assume it's a derivation
                 return findPackageFilename(*state, v, arg);
@@ -591,7 +605,7 @@ bool NixRepl::processLine(std::string line)
         }();
 
         // Open in EDITOR
-        auto args = editorFor(file, line);
+        auto args = editorFor(path, line);
         auto editor = args.front();
         args.pop_front();
 
@@ -627,7 +641,12 @@ bool NixRepl::processLine(std::string line)
         Path drvPathRaw = state->store->printStorePath(drvPath);
 
         if (command == ":b" || command == ":bl") {
-            state->store->buildPaths({DerivedPath::Built{drvPath}});
+            state->store->buildPaths({
+                DerivedPath::Built {
+                    .drvPath = drvPath,
+                    .outputs = OutputsSpec::All { },
+                },
+            });
             auto drv = state->store->readDerivation(drvPath);
             logger->cout("\nThis derivation produced the following outputs:");
             for (auto & [outputName, outputPath] : state->store->queryDerivationOutputMap(drvPath)) {
@@ -773,7 +792,7 @@ void NixRepl::loadFlake(const std::string & flakeRefS)
             flake::LockFlags {
                 .updateLockFile = false,
                 .useRegistries = !evalSettings.pureEval,
-                .allowMutable  = !evalSettings.pureEval,
+                .allowUnlocked = !evalSettings.pureEval,
             }),
         v);
     addAttrsToScope(v);
@@ -1037,10 +1056,11 @@ void runRepl(
 
 struct CmdRepl : InstallablesCommand
 {
-    CmdRepl(){
+    CmdRepl() {
         evalSettings.pureEval = false;
     }
-    void prepare()
+
+    void prepare() override
     {
         if (!settings.isExperimentalFeatureEnabled(Xp::ReplFlake) && !(file) && this->_installables.size() >= 1) {
             warn("future versions of Nix will require using `--file` to load a file");
@@ -1053,12 +1073,15 @@ struct CmdRepl : InstallablesCommand
         }
         installables = InstallablesCommand::load();
     }
+
     std::vector<std::string> files;
+
     Strings getDefaultFlakeAttrPaths() override
     {
         return {""};
     }
-    virtual bool useDefaultInstallables() override
+
+    bool useDefaultInstallables() override
     {
         return file.has_value() or expr.has_value();
     }

src/libexpr/eval-cache.cc

@@ -300,7 +300,7 @@ struct AttrDb
                 NixStringContext context;
                 if (!queryAttribute.isNull(3))
                     for (auto & s : tokenizeString<std::vector<std::string>>(queryAttribute.getStr(3), ";"))
-                        context.push_back(decodeContext(cfg, s));
+                        context.push_back(NixStringContextElem::parse(cfg, s));
                 return {{rowId, string_t{queryAttribute.getStr(2), context}}};
             }
             case AttrType::Bool:
@@ -486,7 +486,7 @@ std::shared_ptr<AttrCursor> AttrCursor::maybeGetAttr(Symbol name, bool forceErro
                         return nullptr;
                     else if (std::get_if<failed_t>(&attr->second)) {
                         if (forceErrors)
-                            debug("reevaluating failed cached attribute '%s'");
+                            debug("reevaluating failed cached attribute '%s'", getAttrPathStr(name));
                         else
                             throw CachedEvalError("cached failure of attribute '%s'", getAttrPathStr(name));
                     } else
@@ -507,11 +507,6 @@ std::shared_ptr<AttrCursor> AttrCursor::maybeGetAttr(Symbol name, bool forceErro
         return nullptr;
         //throw TypeError("'%s' is not an attribute set", getAttrPathStr());
 
-    for (auto & attr : *v.attrs) {
-        if (root->db)
-            root->db->setPlaceholder({cachedValue->first, attr.name});
-    }
-
     auto attr = v.attrs->get(name);
 
     if (!attr) {
@@ -597,7 +592,18 @@ string_t AttrCursor::getStringWithContext()
             if (auto s = std::get_if<string_t>(&cachedValue->second)) {
                 bool valid = true;
                 for (auto & c : s->second) {
-                    if (!root->state.store->isValidPath(c.first)) {
+                    const StorePath & path = std::visit(overloaded {
+                        [&](const NixStringContextElem::DrvDeep & d) -> const StorePath & {
+                            return d.drvPath;
+                        },
+                        [&](const NixStringContextElem::Built & b) -> const StorePath & {
+                            return b.drvPath;
+                        },
+                        [&](const NixStringContextElem::Opaque & o) -> const StorePath & {
+                            return o.path;
+                        },
+                    }, c.raw());
+                    if (!root->state.store->isValidPath(path)) {
                         valid = false;
                         break;
                     }
@@ -650,17 +656,17 @@ NixInt AttrCursor::getInt()
             cachedValue = root->db->getAttr(getKey());
         if (cachedValue && !std::get_if<placeholder_t>(&cachedValue->second)) {
             if (auto i = std::get_if<int_t>(&cachedValue->second)) {
-                debug("using cached Integer attribute '%s'", getAttrPathStr());
+                debug("using cached integer attribute '%s'", getAttrPathStr());
                 return i->x;
             } else
-                throw TypeError("'%s' is not an Integer", getAttrPathStr());
+                throw TypeError("'%s' is not an integer", getAttrPathStr());
         }
     }
 
     auto & v = forceValue();
 
     if (v.type() != nInt)
-        throw TypeError("'%s' is not an Integer", getAttrPathStr());
+        throw TypeError("'%s' is not an integer", getAttrPathStr());
 
     return v.integer;
 }

src/libexpr/eval.cc

@@ -7,7 +7,6 @@
 #include "globals.hh"
 #include "eval-inline.hh"
 #include "filetransfer.hh"
-#include "json.hh"
 #include "function-trace.hh"
 
 #include <algorithm>
@@ -21,6 +20,7 @@
 #include <functional>
 
 #include <sys/resource.h>
+#include <nlohmann/json.hpp>
 
 #if HAVE_BOEHMGC
 
@@ -35,6 +35,8 @@
 
 #endif
 
+using json = nlohmann::json;
+
 namespace nix {
 
 static char * allocString(size_t size)
@@ -43,7 +45,7 @@ static char * allocString(size_t size)
 #if HAVE_BOEHMGC
     t = (char *) GC_MALLOC_ATOMIC(size);
 #else
-    t = malloc(size);
+    t = (char *) malloc(size);
 #endif
     if (!t) throw std::bad_alloc();
     return t;
@@ -65,26 +67,19 @@ static char * dupString(const char * s)
 
 // When there's no need to write to the string, we can optimize away empty
 // string allocations.
-// This function handles makeImmutableStringWithLen(null, 0) by returning the
-// empty string.
-static const char * makeImmutableStringWithLen(const char * s, size_t size)
+// This function handles makeImmutableString(std::string_view()) by returning
+// the empty string.
+static const char * makeImmutableString(std::string_view s)
 {
-    char * t;
+    const size_t size = s.size();
     if (size == 0)
         return "";
-#if HAVE_BOEHMGC
-    t = GC_STRNDUP(s, size);
-#else
-    t = strndup(s, size);
-#endif
-    if (!t) throw std::bad_alloc();
+    auto t = allocString(size + 1);
+    memcpy(t, s.data(), size);
+    t[size] = '\0';
     return t;
 }
 
-static inline const char * makeImmutableString(std::string_view s) {
-    return makeImmutableStringWithLen(s.data(), s.size());
-}
-
 
 RootValue allocRootValue(Value * v)
 {
@@ -404,7 +399,8 @@ static Strings parseNixPath(const std::string & s)
         }
 
         if (*p == ':') {
-            if (isUri(std::string(start2, s.end()))) {
+            auto prefix = std::string(start2, s.end());
+            if (EvalSettings::isPseudoUrl(prefix) || hasPrefix(prefix, "flake:")) {
                 ++p;
                 while (p != s.end() && *p != ':') ++p;
             }
@@ -472,9 +468,6 @@ EvalState::EvalState(
 #if HAVE_BOEHMGC
     , valueAllocCache(std::allocate_shared<void *>(traceable_allocator<void *>(), nullptr))
     , env1AllocCache(std::allocate_shared<void *>(traceable_allocator<void *>(), nullptr))
-#else
-    , valueAllocCache(std::make_shared<void *>(nullptr))
-    , env1AllocCache(std::make_shared<void *>(nullptr))
 #endif
     , baseEnv(allocEnv(128))
     , staticBaseEnv{std::make_shared<StaticEnv>(false, nullptr)}
@@ -824,7 +817,7 @@ void EvalState::runDebugRepl(const Error * error, const Env & env, const Expr &
         ? std::make_unique<DebugTraceStacker>(
             *this,
             DebugTrace {
-                .pos = error->info().errPos ? *error->info().errPos : positions[expr.getPos()],
+                .pos = error->info().errPos ? error->info().errPos : static_cast<std::shared_ptr<AbstractPos>>(positions[expr.getPos()]),
                 .expr = expr,
                 .env = env,
                 .hint = error->info().msg,
@@ -904,7 +897,7 @@ void EvalState::throwEvalError(const char * s, const std::string & s2,
     const std::string & s3)
 {
     debugThrowLastTrace(EvalError({
-        .msg = hintfmt(s, s2),
+        .msg = hintfmt(s, s2, s3),
         .errPos = positions[noPos]
     }));
 }
@@ -913,7 +906,7 @@ void EvalState::throwEvalError(const PosIdx pos, const char * s, const std::stri
     const std::string & s3)
 {
     debugThrowLastTrace(EvalError({
-        .msg = hintfmt(s, s2),
+        .msg = hintfmt(s, s2, s3),
         .errPos = positions[pos]
     }));
 }
@@ -922,7 +915,7 @@ void EvalState::throwEvalError(const PosIdx pos, const char * s, const std::stri
     const std::string & s3, Env & env, Expr & expr)
 {
     debugThrow(EvalError({
-        .msg = hintfmt(s, s2),
+        .msg = hintfmt(s, s2, s3),
         .errPos = positions[pos]
     }), env, expr);
 }
@@ -1013,7 +1006,7 @@ void EvalState::throwMissingArgumentError(const PosIdx pos, const char * s, cons
 
 void EvalState::addErrorTrace(Error & e, const char * s, const std::string & s2) const
 {
-    e.addTrace(std::nullopt, s, s2);
+    e.addTrace(nullptr, s, s2);
 }
 
 void EvalState::addErrorTrace(Error & e, const PosIdx pos, const char * s, const std::string & s2) const
@@ -1025,13 +1018,13 @@ static std::unique_ptr<DebugTraceStacker> makeDebugTraceStacker(
     EvalState & state,
     Expr & expr,
     Env & env,
-    std::optional<ErrPos> pos,
+    std::shared_ptr<AbstractPos> && pos,
     const char * s,
     const std::string & s2)
 {
     return std::make_unique<DebugTraceStacker>(state,
         DebugTrace {
-            .pos = pos,
+            .pos = std::move(pos),
             .expr = expr,
             .env = env,
             .hint = hintfmt(s, s2),
@@ -1137,9 +1130,9 @@ void EvalState::mkThunk_(Value & v, Expr * expr)
 void EvalState::mkPos(Value & v, PosIdx p)
 {
     auto pos = positions[p];
-    if (!pos.file.empty()) {
+    if (auto path = std::get_if<Path>(&pos.origin)) {
         auto attrs = buildBindings(3);
-        attrs.alloc(sFile).mkString(pos.file);
+        attrs.alloc(sFile).mkString(*path);
         attrs.alloc(sLine).mkInt(pos.line);
         attrs.alloc(sColumn).mkInt(pos.column);
         v.mkAttrs(attrs);
@@ -1247,7 +1240,7 @@ void EvalState::cacheFile(
                 *this,
                 *e,
                 this->baseEnv,
-                e->getPos() ? std::optional(ErrPos(positions[e->getPos()])) : std::nullopt,
+                e->getPos() ? static_cast<std::shared_ptr<AbstractPos>>(positions[e->getPos()]) : nullptr,
                 "while evaluating the file '%1%':", resolvedPath)
             : nullptr;
 
@@ -1518,10 +1511,13 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
         state.forceValue(*vAttrs, (pos2 ? pos2 : this->pos ) );
 
     } catch (Error & e) {
-        auto pos2r = state.positions[pos2];
-        if (pos2 && pos2r.file != state.derivationNixPath)
-            state.addErrorTrace(e, pos2, "while evaluating the attribute '%1%'",
-                showAttrPath(state, env, attrPath));
+        if (pos2) {
+            auto pos2r = state.positions[pos2];
+            auto origin = std::get_if<Path>(&pos2r.origin);
+            if (!(origin && *origin == state.derivationNixPath))
+                state.addErrorTrace(e, pos2, "while evaluating the attribute '%1%'",
+                    showAttrPath(state, env, attrPath));
+        }
         throw;
     }
 
@@ -1648,7 +1644,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                 auto dts = debugRepl
                     ? makeDebugTraceStacker(
                         *this, *lambda.body, env2, positions[lambda.pos],
-                        "while evaluating %s",
+                        "while calling %s",
                         lambda.name
                         ? concatStrings("'", symbols[lambda.name], "'")
                         : "anonymous lambda")
@@ -1657,11 +1653,11 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                 lambda.body->eval(*this, env2, vCur);
             } catch (Error & e) {
                 if (loggerSettings.showTrace.get()) {
-                    addErrorTrace(e, lambda.pos, "while evaluating %s",
+                    addErrorTrace(e, lambda.pos, "while calling %s",
                         (lambda.name
                             ? concatStrings("'", symbols[lambda.name], "'")
                             : "anonymous lambda"));
-                    addErrorTrace(e, pos, "from call site%s", "");
+                    addErrorTrace(e, pos, "while evaluating call site%s", "");
                 }
                 throw;
             }
@@ -1808,7 +1804,7 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
 Nix attempted to evaluate a function as a top level expression; in
 this case it must have its arguments supplied either by default
 values, or passed explicitly with '--arg' or '--argstr'. See
-https://nixos.org/manual/nix/stable/expressions/language-constructs.html#functions.)", symbols[i.name],                 
+https://nixos.org/manual/nix/stable/language/constructs.html#functions.)", symbols[i.name],
                 *fun.lambda.env, *fun.lambda.fun);
             }
         }
@@ -2149,27 +2145,6 @@ std::string_view EvalState::forceString(Value & v, const PosIdx pos)
 }
 
 
-/* Decode a context string ‘!<name>!<path>’ into a pair <path,
-   name>. */
-NixStringContextElem decodeContext(const Store & store, std::string_view s)
-{
-    if (s.at(0) == '!') {
-        size_t index = s.find("!", 1);
-        return {
-            store.parseStorePath(s.substr(index + 1)),
-            std::string(s.substr(1, index - 1)),
-        };
-    } else
-        return {
-            store.parseStorePath(
-                s.at(0) == '/'
-                ? s
-                : s.substr(1)),
-            "",
-        };
-}
-
-
 void copyContext(const Value & v, PathSet & context)
 {
     if (v.string.context)
@@ -2184,7 +2159,7 @@ NixStringContext Value::getContext(const Store & store)
     assert(internalType == tString);
     if (string.context)
         for (const char * * p = string.context; *p; ++p)
-            res.push_back(decodeContext(store, *p));
+            res.push_back(NixStringContextElem::parse(store, *p));
     return res;
 }
 
@@ -2251,7 +2226,7 @@ BackedStringView EvalState::coerceToString(const PosIdx pos, Value & v, PathSet
         if (canonicalizePath)
             path = canonPath(*path);
         if (copyToStore)
-            path = copyPathToStore(context, std::move(path).toOwned());
+            path = store->printStorePath(copyPathToStore(context, std::move(path).toOwned()));
         return path;
     }
 
@@ -2294,26 +2269,26 @@ BackedStringView EvalState::coerceToString(const PosIdx pos, Value & v, PathSet
 }
 
 
-std::string EvalState::copyPathToStore(PathSet & context, const Path & path)
+StorePath EvalState::copyPathToStore(PathSet & context, const Path & path)
 {
     if (nix::isDerivation(path))
         throwEvalError("file names are not allowed to end in '%1%'", drvExtension);
 
-    Path dstPath;
-    auto i = srcToStore.find(path);
-    if (i != srcToStore.end())
-        dstPath = store->printStorePath(i->second);
-    else {
-        auto p = settings.readOnlyMode
+    auto dstPath = [&]() -> StorePath
+    {
+        auto i = srcToStore.find(path);
+        if (i != srcToStore.end()) return i->second;
+
+        auto dstPath = settings.readOnlyMode
             ? store->computeStorePathForPath(std::string(baseNameOf(path)), checkSourcePath(path)).first
             : store->addToStore(std::string(baseNameOf(path)), checkSourcePath(path), FileIngestionMethod::Recursive, htSHA256, defaultPathFilter, repair);
-        dstPath = store->printStorePath(p);
-        allowPath(p);
-        srcToStore.insert_or_assign(path, std::move(p));
-        printMsg(lvlChatty, "copied source '%1%' -> '%2%'", path, dstPath);
-    }
+        allowPath(dstPath);
+        srcToStore.insert_or_assign(path, dstPath);
+        printMsg(lvlChatty, "copied source '%1%' -> '%2%'", path, store->printStorePath(dstPath));
+        return dstPath;
+    }();
 
-    context.insert(dstPath);
+    context.insert(store->printStorePath(dstPath));
     return dstPath;
 }
 
@@ -2441,97 +2416,99 @@ void EvalState::printStats()
         std::fstream fs;
         if (outPath != "-")
             fs.open(outPath, std::fstream::out);
-        JSONObject topObj(outPath == "-" ? std::cerr : fs, true);
-        topObj.attr("cpuTime",cpuTime);
-        {
-            auto envs = topObj.object("envs");
-            envs.attr("number", nrEnvs);
-            envs.attr("elements", nrValuesInEnvs);
-            envs.attr("bytes", bEnvs);
-        }
-        {
-            auto lists = topObj.object("list");
-            lists.attr("elements", nrListElems);
-            lists.attr("bytes", bLists);
-            lists.attr("concats", nrListConcats);
-        }
-        {
-            auto values = topObj.object("values");
-            values.attr("number", nrValues);
-            values.attr("bytes", bValues);
-        }
-        {
-            auto syms = topObj.object("symbols");
-            syms.attr("number", symbols.size());
-            syms.attr("bytes", symbols.totalSize());
-        }
-        {
-            auto sets = topObj.object("sets");
-            sets.attr("number", nrAttrsets);
-            sets.attr("bytes", bAttrsets);
-            sets.attr("elements", nrAttrsInAttrsets);
-        }
-        {
-            auto sizes = topObj.object("sizes");
-            sizes.attr("Env", sizeof(Env));
-            sizes.attr("Value", sizeof(Value));
-            sizes.attr("Bindings", sizeof(Bindings));
-            sizes.attr("Attr", sizeof(Attr));
-        }
-        topObj.attr("nrOpUpdates", nrOpUpdates);
-        topObj.attr("nrOpUpdateValuesCopied", nrOpUpdateValuesCopied);
-        topObj.attr("nrThunks", nrThunks);
-        topObj.attr("nrAvoided", nrAvoided);
-        topObj.attr("nrLookups", nrLookups);
-        topObj.attr("nrPrimOpCalls", nrPrimOpCalls);
-        topObj.attr("nrFunctionCalls", nrFunctionCalls);
+        json topObj = json::object();
+        topObj["cpuTime"] = cpuTime;
+        topObj["envs"] = {
+            {"number", nrEnvs},
+            {"elements", nrValuesInEnvs},
+            {"bytes", bEnvs},
+        };
+        topObj["list"] = {
+            {"elements", nrListElems},
+            {"bytes", bLists},
+            {"concats", nrListConcats},
+        };
+        topObj["values"] = {
+            {"number", nrValues},
+            {"bytes", bValues},
+        };
+        topObj["symbols"] = {
+            {"number", symbols.size()},
+            {"bytes", symbols.totalSize()},
+        };
+        topObj["sets"] = {
+            {"number", nrAttrsets},
+            {"bytes", bAttrsets},
+            {"elements", nrAttrsInAttrsets},
+        };
+        topObj["sizes"] = {
+            {"Env", sizeof(Env)},
+            {"Value", sizeof(Value)},
+            {"Bindings", sizeof(Bindings)},
+            {"Attr", sizeof(Attr)},
+        };
+        topObj["nrOpUpdates"] = nrOpUpdates;
+        topObj["nrOpUpdateValuesCopied"] = nrOpUpdateValuesCopied;
+        topObj["nrThunks"] = nrThunks;
+        topObj["nrAvoided"] = nrAvoided;
+        topObj["nrLookups"] = nrLookups;
+        topObj["nrPrimOpCalls"] = nrPrimOpCalls;
+        topObj["nrFunctionCalls"] = nrFunctionCalls;
 #if HAVE_BOEHMGC
-        {
-            auto gc = topObj.object("gc");
-            gc.attr("heapSize", heapSize);
-            gc.attr("totalBytes", totalBytes);
-        }
+        topObj["gc"] = {
+            {"heapSize", heapSize},
+            {"totalBytes", totalBytes},
+        };
 #endif
 
         if (countCalls) {
+            topObj["primops"] = primOpCalls;
             {
-                auto obj = topObj.object("primops");
-                for (auto & i : primOpCalls)
-                    obj.attr(i.first, i.second);
-            }
-            {
-                auto list = topObj.list("functions");
-                for (auto & i : functionCalls) {
-                    auto obj = list.object();
-                    if (i.first->name)
-                        obj.attr("name", (const std::string &) i.first->name);
+                auto& list = topObj["functions"];
+                list = json::array();
+                for (auto & [fun, count] : functionCalls) {
+                    json obj = json::object();
+                    if (fun->name)
+                        obj["name"] = (std::string_view) symbols[fun->name];
                     else
-                        obj.attr("name", nullptr);
-                    if (auto pos = positions[i.first->pos]) {
-                        obj.attr("file", (const std::string &) pos.file);
-                        obj.attr("line", pos.line);
-                        obj.attr("column", pos.column);
+                        obj["name"] = nullptr;
+                    if (auto pos = positions[fun->pos]) {
+                        if (auto path = std::get_if<Path>(&pos.origin))
+                            obj["file"] = *path;
+                        obj["line"] = pos.line;
+                        obj["column"] = pos.column;
                     }
-                    obj.attr("count", i.second);
+                    obj["count"] = count;
+                    list.push_back(obj);
                 }
             }
             {
-                auto list = topObj.list("attributes");
+                auto list = topObj["attributes"];
+                list = json::array();
                 for (auto & i : attrSelects) {
-                    auto obj = list.object();
+                    json obj = json::object();
                     if (auto pos = positions[i.first]) {
-                        obj.attr("file", (const std::string &) pos.file);
-                        obj.attr("line", pos.line);
-                        obj.attr("column", pos.column);
+                        if (auto path = std::get_if<Path>(&pos.origin))
+                            obj["file"] = *path;
+                        obj["line"] = pos.line;
+                        obj["column"] = pos.column;
                     }
-                    obj.attr("count", i.second);
+                    obj["count"] = i.second;
+                    list.push_back(obj);
                 }
             }
         }
 
         if (getEnv("NIX_SHOW_SYMBOLS").value_or("0") != "0") {
-            auto list = topObj.list("symbols");
-            symbols.dump([&](const std::string & s) { list.elem(s); });
+            // XXX: overrides earlier assignment
+            topObj["symbols"] = json::array();
+            auto &list = topObj["symbols"];
+            symbols.dump([&](const std::string & s) { list.emplace_back(s); });
+        }
+        if (outPath == "-") {
+            std::cerr << topObj.dump(2) << std::endl;
+        } else {
+            fs << topObj.dump(2) << std::endl;
         }
     }
 }
@@ -2585,6 +2562,23 @@ Strings EvalSettings::getDefaultNixPath()
     return res;
 }
 
+bool EvalSettings::isPseudoUrl(std::string_view s)
+{
+    if (s.compare(0, 8, "channel:") == 0) return true;
+    size_t pos = s.find("://");
+    if (pos == std::string::npos) return false;
+    std::string scheme(s, 0, pos);
+    return scheme == "http" || scheme == "https" || scheme == "file" || scheme == "channel" || scheme == "git" || scheme == "s3" || scheme == "ssh";
+}
+
+std::string EvalSettings::resolvePseudoUrl(std::string_view url)
+{
+    if (hasPrefix(url, "channel:"))
+        return "https://nixos.org/channels/" + std::string(url.substr(8)) + "/nixexprs.tar.xz";
+    else
+        return std::string(url);
+}
+
 EvalSettings evalSettings;
 
 static GlobalConfig::Register rEvalSettings(&evalSettings);

src/libexpr/eval.hh

@@ -60,7 +60,6 @@ void copyContext(const Value & v, PathSet & context);
 typedef std::map<Path, StorePath> SrcToStore;
 
 
-std::ostream & printValue(const EvalState & state, std::ostream & str, const Value & v);
 std::string printValue(const EvalState & state, const Value & v);
 std::ostream & operator << (std::ostream & os, const ValueType t);
 
@@ -78,7 +77,7 @@ struct RegexCache;
 std::shared_ptr<RegexCache> makeRegexCache();
 
 struct DebugTrace {
-    std::optional<ErrPos> pos;
+    std::shared_ptr<AbstractPos> pos;
     const Expr & expr;
     const Env & env;
     hintformat hint;
@@ -400,7 +399,7 @@ public:
         bool coerceMore = false, bool copyToStore = true,
         bool canonicalizePath = true);
 
-    std::string copyPathToStore(PathSet & context, const Path & path);
+    StorePath copyPathToStore(PathSet & context, const Path & path);
 
     /* Path coercion.  Converts strings, paths and derivations to a
        path.  The result is guaranteed to be a canonicalised, absolute
@@ -457,8 +456,12 @@ private:
     friend struct ExprAttrs;
     friend struct ExprLet;
 
-    Expr * parse(char * text, size_t length, FileOrigin origin, const PathView path,
-        const PathView basePath, std::shared_ptr<StaticEnv> & staticEnv);
+    Expr * parse(
+        char * text,
+        size_t length,
+        Pos::Origin origin,
+        Path basePath,
+        std::shared_ptr<StaticEnv> & staticEnv);
 
 public:
 
@@ -568,10 +571,6 @@ struct DebugTraceStacker {
 std::string_view showType(ValueType type);
 std::string showType(const Value & v);
 
-/* Decode a context string ‘!<name>!<path>’ into a pair <path,
-   name>. */
-NixStringContextElem decodeContext(const Store & store, std::string_view s);
-
 /* If `path' refers to a directory, then append "/default.nix". */
 Path resolveExprPath(Path path);
 
@@ -590,6 +589,10 @@ struct EvalSettings : Config
 
     static Strings getDefaultNixPath();
 
+    static bool isPseudoUrl(std::string_view s);
+
+    static std::string resolvePseudoUrl(std::string_view url);
+
     Setting<bool> enableNativeCode{this, false, "allow-unsafe-native-code-during-evaluation",
         "Whether builtin functions that allow executing native code should be enabled."};
 

src/libexpr/fetchurl.nix

@@ -12,13 +12,13 @@
 , executable ? false
 , unpack ? false
 , name ? baseNameOf (toString url)
+, impure ? false
 }:
 
-derivation {
+derivation ({
   builder = "builtin:fetchurl";
 
   # New-style output content requirements.
-  inherit outputHashAlgo outputHash;
   outputHashMode = if unpack || executable then "recursive" else "flat";
 
   inherit name url executable unpack;
@@ -38,4 +38,6 @@ derivation {
 
   # To make "nix-prefetch-url" work.
   urls = [ url ];
-}
+} // (if impure
+      then { __impure = true; }
+      else { inherit outputHashAlgo outputHash; }))

src/libexpr/flake/call-flake.nix

@@ -43,7 +43,7 @@ let
 
           outputs = flake.outputs (inputs // { self = result; });
 
-          result = outputs // sourceInfo // { inherit inputs; inherit outputs; inherit sourceInfo; };
+          result = outputs // sourceInfo // { inherit inputs; inherit outputs; inherit sourceInfo; _type = "flake"; };
         in
           if node.flake or true then
             assert builtins.isFunction flake.outputs;

src/libexpr/flake/config.cc

@@ -56,7 +56,7 @@ void ConfigFile::apply()
             auto tlname = get(trustedList, name);
             if (auto saved = tlname ? get(*tlname, valueS) : nullptr) {
                 trusted = *saved;
-                warn("Using saved setting for '%s = %s' from ~/.local/share/nix/trusted-settings.json.", name,valueS);
+                printInfo("Using saved setting for '%s = %s' from ~/.local/share/nix/trusted-settings.json.", name, valueS);
             } else {
                 // FIXME: filter ANSI escapes, newlines, \r, etc.
                 if (std::tolower(logger->ask(fmt("do you want to allow configuration setting '%s' to be set to '" ANSI_RED "%s" ANSI_NORMAL "' (y/N)?", name, valueS)).value_or('n')) == 'y') {
@@ -68,7 +68,7 @@ void ConfigFile::apply()
                 }
             }
             if (!trusted) {
-                warn("ignoring untrusted flake configuration setting '%s'", name);
+                warn("ignoring untrusted flake configuration setting '%s'.\nPass '%s' to trust it", name, "--accept-flake-config");
                 continue;
             }
         }

src/libexpr/flake/flake.cc

@@ -143,7 +143,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
         } catch (Error & e) {
             e.addTrace(
                 state.positions[attr.pos],
-                hintfmt("in flake attribute '%s'", state.symbols[attr.name]));
+                hintfmt("while evaluating flake attribute '%s'", state.symbols[attr.name]));
             throw;
         }
     }
@@ -152,7 +152,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
         try {
             input.ref = FlakeRef::fromAttrs(attrs);
         } catch (Error & e) {
-            e.addTrace(state.positions[pos], hintfmt("in flake input"));
+            e.addTrace(state.positions[pos], hintfmt("while evaluating flake input"));
             throw;
         }
     else {
@@ -220,7 +220,7 @@ static Flake getFlake(
     Value vInfo;
     state.evalFile(flakeFile, vInfo, true); // FIXME: symlink attack
 
-    expectType(state, nAttrs, vInfo, state.positions.add({flakeFile, foFile}, 0, 0));
+    expectType(state, nAttrs, vInfo, state.positions.add({flakeFile}, 1, 1));
 
     if (auto description = vInfo.attrs->get(state.sDescription)) {
         expectType(state, nString, *description->value, description->pos);
@@ -341,7 +341,6 @@ LockedFlake lockFlake(
 
         debug("old lock file: %s", oldLockFile);
 
-        // FIXME: check whether all overrides are used.
         std::map<InputPath, FlakeInput> overrides;
         std::set<InputPath> overridesUsed, updatesUsed;
 
@@ -354,7 +353,7 @@ LockedFlake lockFlake(
 
         std::function<void(
             const FlakeInputs & flakeInputs,
-            std::shared_ptr<Node> node,
+            ref<Node> node,
             const InputPath & inputPathPrefix,
             std::shared_ptr<const Node> oldNode,
             const InputPath & lockRootPath,
@@ -363,9 +362,15 @@ LockedFlake lockFlake(
             computeLocks;
 
         computeLocks = [&](
+            /* The inputs of this node, either from flake.nix or
+               flake.lock. */
             const FlakeInputs & flakeInputs,
-            std::shared_ptr<Node> node,
+            /* The node whose locks are to be updated.*/
+            ref<Node> node,
+            /* The path to this node in the lock file graph. */
             const InputPath & inputPathPrefix,
+            /* The old node, if any, from which locks can be
+               copied. */
             std::shared_ptr<const Node> oldNode,
             const InputPath & lockRootPath,
             const Path & parentPath,
@@ -384,6 +389,18 @@ LockedFlake lockFlake(
                 }
             }
 
+            /* Check whether this input has overrides for a
+               non-existent input. */
+            for (auto [inputPath, inputOverride] : overrides) {
+                auto inputPath2(inputPath);
+                auto follow = inputPath2.back();
+                inputPath2.pop_back();
+                if (inputPath2 == inputPathPrefix && !flakeInputs.count(follow))
+                    warn(
+                        "input '%s' has an override for a non-existent input '%s'",
+                        printInputPath(inputPathPrefix), follow);
+            }
+
             /* Go over the flake inputs, resolve/fetch them if
                necessary (i.e. if they're new or the flakeref changed
                from what's in the lock file). */
@@ -441,7 +458,7 @@ LockedFlake lockFlake(
                         /* Copy the input from the old lock since its flakeref
                            didn't change and there is no override from a
                            higher level flake. */
-                        auto childNode = std::make_shared<LockedNode>(
+                        auto childNode = make_ref<LockedNode>(
                             oldLock->lockedRef, oldLock->originalRef, oldLock->isFlake);
 
                         node->inputs.insert_or_assign(id, childNode);
@@ -470,14 +487,14 @@ LockedFlake lockFlake(
                                         .isFlake = (*lockedNode)->isFlake,
                                     });
                                 } else if (auto follows = std::get_if<1>(&i.second)) {
-                                    if (! trustLock) {
+                                    if (!trustLock) {
                                         // It is possible that the flake has changed,
-                                        // so we must confirm all the follows that are in the lockfile are also in the flake.
+                                        // so we must confirm all the follows that are in the lock file are also in the flake.
                                         auto overridePath(inputPath);
                                         overridePath.push_back(i.first);
                                         auto o = overrides.find(overridePath);
                                         // If the override disappeared, we have to refetch the flake,
-                                        // since some of the inputs may not be present in the lockfile.
+                                        // since some of the inputs may not be present in the lock file.
                                         if (o == overrides.end()) {
                                             mustRefetch = true;
                                             // There's no point populating the rest of the fake inputs,
@@ -510,8 +527,8 @@ LockedFlake lockFlake(
                            this input. */
                         debug("creating new input '%s'", inputPathS);
 
-                        if (!lockFlags.allowMutable && !input.ref->input.isLocked())
-                            throw Error("cannot update flake input '%s' in pure mode", inputPathS);
+                        if (!lockFlags.allowUnlocked && !input.ref->input.isLocked())
+                            throw Error("cannot update unlocked flake input '%s' in pure mode", inputPathS);
 
                         /* Note: in case of an --override-input, we use
                             the *original* ref (input2.ref) for the
@@ -533,7 +550,7 @@ LockedFlake lockFlake(
 
                             auto inputFlake = getFlake(state, localRef, useRegistries, flakeCache, inputPath);
 
-                            auto childNode = std::make_shared<LockedNode>(inputFlake.lockedRef, ref);
+                            auto childNode = make_ref<LockedNode>(inputFlake.lockedRef, ref);
 
                             node->inputs.insert_or_assign(id, childNode);
 
@@ -553,15 +570,19 @@ LockedFlake lockFlake(
                                 oldLock
                                 ? std::dynamic_pointer_cast<const Node>(oldLock)
                                 : LockFile::read(
-                                    inputFlake.sourceInfo->actualPath + "/" + inputFlake.lockedRef.subdir + "/flake.lock").root,
-                                oldLock ? lockRootPath : inputPath, localPath, false);
+                                    inputFlake.sourceInfo->actualPath + "/" + inputFlake.lockedRef.subdir + "/flake.lock").root.get_ptr(),
+                                oldLock ? lockRootPath : inputPath,
+                                localPath,
+                                false);
                         }
 
                         else {
                             auto [sourceInfo, resolvedRef, lockedRef] = fetchOrSubstituteTree(
                                 state, *input.ref, useRegistries, flakeCache);
-                            node->inputs.insert_or_assign(id,
-                                std::make_shared<LockedNode>(lockedRef, ref, false));
+
+                            auto childNode = make_ref<LockedNode>(lockedRef, ref, false);
+
+                            node->inputs.insert_or_assign(id, childNode);
                         }
                     }
 
@@ -576,8 +597,13 @@ LockedFlake lockFlake(
         auto parentPath = canonPath(flake.sourceInfo->actualPath + "/" + flake.lockedRef.subdir, true);
 
         computeLocks(
-            flake.inputs, newLockFile.root, {},
-            lockFlags.recreateLockFile ? nullptr : oldLockFile.root, {}, parentPath, false);
+            flake.inputs,
+            newLockFile.root,
+            {},
+            lockFlags.recreateLockFile ? nullptr : oldLockFile.root.get_ptr(),
+            {},
+            parentPath,
+            false);
 
         for (auto & i : lockFlags.inputOverrides)
             if (!overridesUsed.count(i.first))
@@ -600,9 +626,9 @@ LockedFlake lockFlake(
 
             if (lockFlags.writeLockFile) {
                 if (auto sourcePath = topRef.input.getSourcePath()) {
-                    if (!newLockFile.isImmutable()) {
+                    if (auto unlockedInput = newLockFile.isUnlocked()) {
                         if (fetchSettings.warnDirty)
-                            warn("will not write lock file of flake '%s' because it has a mutable input", topRef);
+                            warn("will not write lock file of flake '%s' because it has an unlocked input ('%s')", topRef, *unlockedInput);
                     } else {
                         if (!lockFlags.updateLockFile)
                             throw Error("flake '%s' requires lock file changes but they're not allowed due to '--no-update-lock-file'", topRef);
@@ -726,7 +752,7 @@ static void prim_getFlake(EvalState & state, const PosIdx pos, Value * * args, V
                 .updateLockFile = false,
                 .writeLockFile = false,
                 .useRegistries = !evalSettings.pureEval && fetchSettings.useRegistries,
-                .allowMutable  = !evalSettings.pureEval,
+                .allowUnlocked = !evalSettings.pureEval,
             }),
         v);
 }

src/libexpr/flake/flake.hh

@@ -108,11 +108,11 @@ struct LockFlags
 
     bool applyNixConfig = false;
 
-    /* Whether mutable flake references (i.e. those without a Git
+    /* Whether unlocked flake references (i.e. those without a Git
        revision or similar) without a corresponding lock are
-       allowed. Mutable flake references with a lock are always
+       allowed. Unlocked flake references with a lock are always
        allowed. */
-    bool allowMutable = true;
+    bool allowUnlocked = true;
 
     /* Whether to commit changes to flake.lock. */
     bool commitLockFile = false;