Merge remote-tracking branch 'origin/master' into tarball-cache

.github/labeler.yml

@@ -1,23 +1,30 @@
 "documentation":
-  - doc/manual/*
-  - src/nix/**/*.md
+  - changed-files:
+    - any-glob-to-any-file: "doc/manual/*"
+    - any-glob-to-any-file: "src/nix/**/*.md"
 
 "store":
-  - src/libstore/store-api.*
-  - src/libstore/*-store.*
+  - changed-files:
+    - any-glob-to-any-file: "src/libstore/store-api.*"
+    - any-glob-to-any-file: "src/libstore/*-store.*"
 
 "fetching":
-  - src/libfetchers/**/*
+  - changed-files:
+    - any-glob-to-any-file: "src/libfetchers/**/*"
 
 "repl":
-  - src/libcmd/repl.*
-  - src/nix/repl.*
+  - changed-files:
+    - any-glob-to-any-file: "src/libcmd/repl.*"
+    - any-glob-to-any-file: "src/nix/repl.*"
 
 "new-cli":
-  - src/nix/**/*
+  - changed-files:
+    - any-glob-to-any-file: "src/nix/**/*"
 
 "with-tests":
+  - changed-files:
     # Unit tests
-  - src/*/tests/**/*
+    - any-glob-to-any-file: "src/*/tests/**/*"
     # Functional and integration tests
-  - tests/functional/**/*
+    - any-glob-to-any-file: "tests/functional/**/*"
+    

.github/workflows/backport.yml

@@ -21,7 +21,7 @@ jobs:
           fetch-depth: 0
       - name: Create backport PRs
         # should be kept in sync with `version`
-        uses: zeebe-io/backport-action@v2.1.1
+        uses: zeebe-io/backport-action@v2.2.0
         with:
           # Config README: https://github.com/zeebe-io/backport-action#backport-action
           github_token: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/ci.yml

@@ -20,12 +20,12 @@ jobs:
     - uses: actions/checkout@v4
       with:
         fetch-depth: 0
-    - uses: cachix/install-nix-action@v23
+    - uses: cachix/install-nix-action@v24
       with:
         # The sandbox would otherwise be disabled by default on Darwin
         extra_nix_config: "sandbox = true"
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/cachix-action@v12
+    - uses: cachix/cachix-action@v13
       if: needs.check_secrets.outputs.cachix == 'true'
       with:
         name: '${{ env.CACHIX_NAME }}'
@@ -62,10 +62,10 @@ jobs:
       with:
         fetch-depth: 0
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v23
+    - uses: cachix/install-nix-action@v24
       with:
         install_url: https://releases.nixos.org/nix/nix-2.13.3/install
-    - uses: cachix/cachix-action@v12
+    - uses: cachix/cachix-action@v13
       with:
         name: '${{ env.CACHIX_NAME }}'
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
@@ -84,7 +84,7 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - run: echo CACHIX_NAME="$(echo $GITHUB_REPOSITORY-install-tests | tr "[A-Z]/" "[a-z]-")" >> $GITHUB_ENV
-    - uses: cachix/install-nix-action@v23
+    - uses: cachix/install-nix-action@v24
       with:
         install_url: '${{needs.installer.outputs.installerURL}}'
         install_options: "--tarball-url-prefix https://${{ env.CACHIX_NAME }}.cachix.org/serve"
@@ -114,12 +114,12 @@ jobs:
     - uses: actions/checkout@v4
       with:
         fetch-depth: 0
-    - uses: cachix/install-nix-action@v23
+    - uses: cachix/install-nix-action@v24
       with:
         install_url: https://releases.nixos.org/nix/nix-2.13.3/install
     - run: echo CACHIX_NAME="$(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 \")" >> $GITHUB_ENV
-    - uses: cachix/cachix-action@v12
+    - uses: cachix/cachix-action@v13
       if: needs.check_secrets.outputs.cachix == 'true'
       with:
         name: '${{ env.CACHIX_NAME }}'

.github/workflows/labels.yml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-latest
     if: github.repository_owner == 'NixOS'
     steps:
-    - uses: actions/labeler@v4
+    - uses: actions/labeler@v5
       with:
         repo-token: ${{ secrets.GITHUB_TOKEN }}
         sync-labels: false

.gitignore

@@ -22,6 +22,8 @@ perl/Makefile.config
 /doc/manual/xp-features.json
 /doc/manual/src/SUMMARY.md
 /doc/manual/src/SUMMARY-rl-next.md
+/doc/manual/src/store/types/*
+!/doc/manual/src/store/types/index.md.in
 /doc/manual/src/command-ref/new-cli
 /doc/manual/src/command-ref/conf-file.md
 /doc/manual/src/command-ref/experimental-features-shortlist.md
@@ -43,18 +45,18 @@ perl/Makefile.config
 /src/libexpr/parser-tab.hh
 /src/libexpr/parser-tab.output
 /src/libexpr/nix.tbl
-/src/libexpr/tests/libnixexpr-tests
+/tests/unit/libexpr/libnixexpr-tests
 
 # /src/libstore/
 *.gen.*
-/src/libstore/tests/libnixstore-tests
+/tests/unit/libstore/libnixstore-tests
 
 # /src/libutil/
-/src/libutil/tests/libnixutil-tests
+/tests/unit/libutil/libnixutil-tests
 
 /src/nix/nix
 
-/src/nix/doc
+/src/nix/generated-doc
 
 # /src/nix-env/
 /src/nix-env/nix-env

Makefile

@@ -1,5 +1,7 @@
--include Makefile.config
-clean-files += Makefile.config
+include mk/build-dir.mk
+
+-include $(buildprefix)Makefile.config
+clean-files += $(buildprefix)Makefile.config
 
 ifeq ($(ENABLE_BUILD), yes)
 makefiles = \
@@ -19,17 +21,17 @@ makefiles = \
   misc/zsh/local.mk \
   misc/systemd/local.mk \
   misc/launchd/local.mk \
-  misc/upstart/local.mk \
-  doc/manual/local.mk \
-  doc/internal-api/local.mk
+  misc/upstart/local.mk
 endif
 
 ifeq ($(ENABLE_BUILD)_$(ENABLE_TESTS), yes_yes)
-UNIT_TEST_ENV = _NIX_TEST_UNIT_DATA=unit-test-data
 makefiles += \
-  src/libutil/tests/local.mk \
-  src/libstore/tests/local.mk \
-  src/libexpr/tests/local.mk
+  tests/unit/libutil/local.mk \
+  tests/unit/libutil-support/local.mk \
+  tests/unit/libstore/local.mk \
+  tests/unit/libstore-support/local.mk \
+  tests/unit/libexpr/local.mk \
+  tests/unit/libexpr-support/local.mk
 endif
 
 ifeq ($(ENABLE_TESTS), yes)
@@ -55,4 +57,11 @@ endif
 
 include mk/lib.mk
 
-GLOBAL_CXXFLAGS += -g -Wall -include config.h -std=c++2a -I src
+# Must be included after `mk/lib.mk` so rules refer to variables defined
+# by the library. Rules are not "lazy" like variables, unfortunately.
+ifeq ($(ENABLE_BUILD), yes)
+$(eval $(call include-sub-makefile, doc/manual/local.mk))
+endif
+$(eval $(call include-sub-makefile, doc/internal-api/local.mk))
+
+GLOBAL_CXXFLAGS += -g -Wall -include $(buildprefix)config.h -std=c++2a -I src

boehmgc-traceable_allocator-public.diff

@@ -0,0 +1,12 @@
+diff --git a/include/gc_allocator.h b/include/gc_allocator.h
+index 597c7f13..587286be 100644
+--- a/include/gc_allocator.h
++++ b/include/gc_allocator.h
+@@ -312,6 +312,7 @@ public:
+ 
+ template<>
+ class traceable_allocator<void> {
++public:
+   typedef size_t      size_type;
+   typedef ptrdiff_t   difference_type;
+   typedef void*       pointer;

configure.ac

@@ -122,7 +122,6 @@ AC_PATH_PROG(flex, flex, false)
 AC_PATH_PROG(bison, bison, false)
 AC_PATH_PROG(dot, dot)
 AC_PATH_PROG(lsof, lsof, lsof)
-NEED_PROG(jq, jq)
 
 
 AC_SUBST(coreutils, [$(dirname $(type -p cat))])
@@ -133,6 +132,30 @@ AC_ARG_WITH(store-dir, AS_HELP_STRING([--with-store-dir=PATH],[path of the Nix s
 AC_SUBST(storedir)
 
 
+# Running the functional tests without building Nix is useful for testing
+# different pre-built versions of Nix against each other.
+AC_ARG_ENABLE(build, AS_HELP_STRING([--disable-build],[Do not build nix]),
+  ENABLE_BUILD=$enableval, ENABLE_BUILD=yes)
+AC_SUBST(ENABLE_BUILD)
+
+# Building without tests is useful for bootstrapping with a smaller footprint
+# or running the tests in a separate derivation. Otherwise, we do compile and
+# run them.
+AC_ARG_ENABLE(tests, AS_HELP_STRING([--disable-tests],[Do not build the tests]),
+  ENABLE_TESTS=$enableval, ENABLE_TESTS=yes)
+AC_SUBST(ENABLE_TESTS)
+
+# Building without API docs is the default as Nix' C++ interfaces are internal and unstable.
+AC_ARG_ENABLE(internal_api_docs, AS_HELP_STRING([--enable-internal-api-docs],[Build API docs for Nix's internal unstable C++ interfaces]),
+  internal_api_docs=$enableval, internal_api_docs=no)
+AC_SUBST(internal_api_docs)
+
+AS_IF(
+  [test "$ENABLE_BUILD" == "yes" || test "$ENABLE_TEST" == "yes"],
+  [NEED_PROG(jq, jq)])
+
+AS_IF([test "$ENABLE_BUILD" == "yes"],[
+
 # Look for boost, a required dependency.
 # Note that AX_BOOST_BASE only exports *CPP* BOOST_CPPFLAGS, no CXX flags,
 # and CPPFLAGS are not passed to the C++ compiler automatically.
@@ -155,18 +178,6 @@ if test "x$GCC_ATOMIC_BUILTINS_NEED_LIBATOMIC" = xyes; then
     LDFLAGS="-latomic $LDFLAGS"
 fi
 
-# Running the functional tests without building Nix is useful for testing
-# different pre-built versions of Nix against each other.
-AC_ARG_ENABLE(build, AS_HELP_STRING([--disable-build],[Do not build nix]),
-  ENABLE_BUILD=$enableval, ENABLE_BUILD=yes)
-AC_SUBST(ENABLE_BUILD)
-# Building without tests is useful for bootstrapping with a smaller footprint
-# or running the tests in a separate derivation. Otherwise, we do compile and
-# run them.
-AC_ARG_ENABLE(tests, AS_HELP_STRING([--disable-tests],[Do not build the tests]),
-  ENABLE_TESTS=$enableval, ENABLE_TESTS=yes)
-AC_SUBST(ENABLE_TESTS)
-
 AC_ARG_ENABLE(install-unit-tests, AS_HELP_STRING([--enable-install-unit-tests],[Install the unit tests for running later (default no)]),
   INSTALL_UNIT_TESTS=$enableval, INSTALL_UNIT_TESTS=no)
 AC_SUBST(INSTALL_UNIT_TESTS)
@@ -179,11 +190,6 @@ AC_ARG_WITH(check-lib-dir, AS_HELP_STRING([--with-check-lib-dir=PATH],[path to i
   checklibdir=$withval, checklibdir=$libdir)
 AC_SUBST(checklibdir)
 
-# Building without API docs is the default as Nix' C++ interfaces are internal and unstable.
-AC_ARG_ENABLE(internal_api_docs, AS_HELP_STRING([--enable-internal-api-docs],[Build API docs for Nix's internal unstable C++ interfaces]),
-  internal_api_docs=$enableval, internal_api_docs=no)
-AC_SUBST(internal_api_docs)
-
 # LTO is currently broken with clang for unknown reasons; ld segfaults in the llvm plugin
 AC_ARG_ENABLE(lto, AS_HELP_STRING([--enable-lto],[Enable LTO (only supported with GCC) [default=no]]),
   lto=$enableval, lto=no)
@@ -282,6 +288,8 @@ case "$host_os" in
 esac
 AC_SUBST(HAVE_SECCOMP, [$have_seccomp])
 
+# Optional dependencies for better normalizing file system data
+AC_CHECK_HEADERS[sys/xattr.h]
 
 # Look for aws-cpp-sdk-s3.
 AC_LANG_PUSH(C++)
@@ -308,8 +316,7 @@ if test "$gc" = yes; then
   AC_DEFINE(HAVE_BOEHMGC, 1, [Whether to use the Boehm garbage collector.])
 fi
 
-
-if test "$ENABLE_TESTS" = yes; then
+AS_IF([test "$ENABLE_TESTS" == "yes"],[
 
 # Look for gtest.
 PKG_CHECK_MODULES([GTEST], [gtest_main])
@@ -336,12 +343,11 @@ AC_LINK_IFELSE([
   [AC_MSG_ERROR([librapidcheck is not found.])])
 AC_LANG_POP(C++)
 
-fi
+])
 
 # Look for nlohmann/json.
 PKG_CHECK_MODULES([NLOHMANN_JSON], [nlohmann_json >= 3.9])
 
-
 # documentation generation switch
 AC_ARG_ENABLE(doc-gen, AS_HELP_STRING([--disable-doc-gen],[disable documentation generation]),
   doc_generate=$enableval, doc_generate=yes)
@@ -386,6 +392,8 @@ if test "$embedded_sandbox_shell" = yes; then
   AC_DEFINE(HAVE_EMBEDDED_SANDBOX_SHELL, 1, [Include the sandbox shell in the Nix binary.])
 fi
 
+])
+
 
 # Expand all variables in config.status.
 test "$prefix" = NONE && prefix=$ac_default_prefix

doc/internal-api/doxygen.cfg.in

@@ -39,17 +39,21 @@ INPUT                  = \
   src/libcmd \
   src/libexpr \
   src/libexpr/flake \
-  src/libexpr/tests \
-  src/libexpr/tests/value \
+  tests/unit/libexpr \
+  tests/unit/libexpr/value \
+  tests/unit/libexpr/test \
+  tests/unit/libexpr/test/value \
   src/libexpr/value \
   src/libfetchers \
   src/libmain \
   src/libstore \
   src/libstore/build \
   src/libstore/builtins \
-  src/libstore/tests \
+  tests/unit/libstore \
+  tests/unit/libstore/test \
   src/libutil \
-  src/libutil/tests \
+  tests/unit/libutil \
+  tests/unit/libutil/test \
   src/nix \
   src/nix-env \
   src/nix-store

doc/manual/_redirects

@@ -13,18 +13,28 @@
 # conventions:
 # - always force (<CODE>!) since this allows re-using file names
 # - group related paths to ease readability
-# - always append new redirects to the end of the file
+# - keep in alphabetical/wildcards-last order, which will reduce version control conflicts
 # - redirects that should have been there but are missing can be inserted where they belong
 
+/advanced-topics/advanced-topics /advanced-topics 301!
+
+/command-ref/command-ref /command-ref 301!
+
+/contributing/contributing /contributing 301!
+
 /expressions/expression-language /language/ 301!
-/expressions/language-values /language/values 301!
 /expressions/language-constructs /language/constructs 301!
 /expressions/language-operators /language/operators 301!
+/expressions/language-values /language/values 301!
 /expressions/* /language/:splat 301!
 
+/installation/installation /installation 301!
+
 /package-management/basic-package-mgmt /command-ref/nix-env 301!
+/package-management/channels /command-ref/nix-channel 301!
+/package-management/package-management /package-management 301!
+/package-management/s3-substituter /store/types/s3-binary-cache-store 301!
 
-/package-management/channels* /command-ref/nix-channel 301!
-
-/package-management/s3-substituter* /command-ref/new-cli/nix3-help-stores#s3-binary-cache-store 301!
+/protocols/protocols /protocols 301!
 
+/release-notes/release-notes /release-notes 301!

doc/manual/generate-builtin-constants.nix

@@ -1,6 +1,6 @@
 let
   inherit (builtins) concatStringsSep attrValues mapAttrs;
-  inherit (import ./utils.nix) optionalString squash;
+  inherit (import <nix/utils.nix>) optionalString squash;
 in
 
 builtinsInfo:

doc/manual/generate-builtins.nix

@@ -1,6 +1,6 @@
 let
   inherit (builtins) concatStringsSep attrValues mapAttrs;
-  inherit (import ./utils.nix) optionalString squash;
+  inherit (import <nix/utils.nix>) optionalString squash;
 in
 
 builtinsInfo:
@@ -8,7 +8,15 @@ let
   showBuiltin = name: { doc, args, arity, experimental-feature }:
     let
       experimentalNotice = optionalString (experimental-feature != null) ''
-        This function is only available if the [${experimental-feature}](@docroot@/contributing/experimental-features.md#xp-feature-${experimental-feature}) experimental feature is enabled.
+        > **Note**
+        >
+        > This function is only available if the [`${experimental-feature}` experimental feature](@docroot@/contributing/experimental-features.md#xp-feature-${experimental-feature}) is enabled.
+        >
+        > For example, include the following in [`nix.conf`](@docroot@/command-ref/conf-file.md):
+        >
+        > ```
+        > extra-experimental-features = ${experimental-feature}
+        > ```
       '';
     in
     squash ''
@@ -17,10 +25,9 @@ let
       </dt>
       <dd>
 
-      ${doc}
-
       ${experimentalNotice}
 
+      ${doc}
       </dd>
     '';
   listArgs = args: concatStringsSep " " (map (s: "<var>${s}</var>") args);

doc/manual/generate-manpage.nix

@@ -1,9 +1,29 @@
 let
   inherit (builtins)
-    attrNames attrValues fromJSON listToAttrs mapAttrs groupBy
-    concatStringsSep concatMap length lessThan replaceStrings sort;
-  inherit (import <nix/utils.nix>) attrsToList concatStrings optionalString filterAttrs trim squash unique;
-  showStoreDocs = import ./generate-store-info.nix;
+    attrNames
+    attrValues
+    concatMap
+    concatStringsSep
+    fromJSON
+    groupBy
+    length
+    lessThan
+    listToAttrs
+    mapAttrs
+    match
+    replaceStrings
+    sort
+    ;
+  inherit (import <nix/utils.nix>)
+    attrsToList
+    concatStrings
+    filterAttrs
+    optionalString
+    squash
+    trim
+    unique
+    ;
+  showStoreDocs = import <nix/generate-store-info.nix>;
 in
 
 inlineHTML: commandDump:
@@ -31,7 +51,7 @@ let
 
         ${maybeSubcommands}
 
-        ${maybeStoreDocs}
+        ${maybeProse}
 
         ${maybeOptions}
       '';
@@ -71,17 +91,48 @@ let
         * [`${command} ${name}`](./${appendName filename name}.md) - ${subcmd.description}
       '';
 
-      # FIXME: this is a hack.
-      # store parameters should not be part of command documentation to begin
-      # with, but instead be rendered on separate pages.
-      maybeStoreDocs = optionalString (details ? doc)
-        (replaceStrings [ "@stores@" ] [ (showStoreDocs inlineHTML commandInfo.stores) ] details.doc);
+      maybeProse =
+        # FIXME: this is a horrible hack to keep `nix help-stores` working.
+        # the correct answer to this is to remove that command and replace it
+        # by statically generated manpages or the output of something like `nix
+        # store info <store type>`.
+        let
+          help-stores = ''
+            ${index}
 
-      maybeOptions = let
+            ${allStores}
+          '';
+          index = replaceStrings
+            [ "@store-types@" "./local-store.md" "./local-daemon-store.md" ]
+            [ storesOverview "#local-store" "#local-daemon-store" ]
+            details.doc;
+          storesOverview =
+            let
+              showEntry = store:
+                "- [${store.name}](#${store.slug})";
+            in
+            concatStringsSep "\n" (map showEntry storesList) + "\n";
+          allStores = concatStringsSep "\n" (attrValues storePages);
+          storePages = listToAttrs
+            (map (s: { name = s.filename; value = s.page; }) storesList);
+          storesList = showStoreDocs {
+            storeInfo = commandInfo.stores;
+            inherit inlineHTML;
+          };
+        in
+        optionalString (details ? doc) (
+          if match "@store-types@" details.doc != [ ]
+          then help-stores
+          else details.doc
+        );
+
+      maybeOptions =
+        let
           allVisibleOptions = filterAttrs
             (_: o: ! o.hiddenCategory)
             (details.flags // toplevel.flags);
-      in optionalString (allVisibleOptions != {}) ''
+        in
+        optionalString (allVisibleOptions != { }) ''
           # Options
 
           ${showOptions inlineHTML allVisibleOptions}

doc/manual/generate-settings.nix

@@ -1,6 +1,6 @@
 let
   inherit (builtins) attrValues concatStringsSep isAttrs isBool mapAttrs;
-  inherit (import ./utils.nix) concatStrings indent optionalString squash;
+  inherit (import <nix/utils.nix>) concatStrings indent optionalString squash;
 in
 
 # `inlineHTML` is a hack to accommodate inconsistent output from `lowdown`
@@ -20,10 +20,10 @@ let
         else "`${setting}`";
       # separate body to cleanly handle indentation
       body = ''
-          ${description}
-
           ${experimentalFeatureNote}
 
+          ${description}
+
           **Default:** ${showDefault documentDefault defaultValue}
 
           ${showAliases aliases}
@@ -31,18 +31,19 @@ let
 
       experimentalFeatureNote = optionalString (experimentalFeature != null) ''
           > **Warning**
+          >
           > This setting is part of an
           > [experimental feature](@docroot@/contributing/experimental-features.md).
-
-          To change this setting, you need to make sure the corresponding experimental feature,
-          [`${experimentalFeature}`](@docroot@/contributing/experimental-features.md#xp-feature-${experimentalFeature}),
-          is enabled.
-          For example, include the following in [`nix.conf`](#):
-
-          ```
-          extra-experimental-features = ${experimentalFeature}
-          ${setting} = ...
-          ```
+          >
+          > To change this setting, make sure the
+          > [`${experimentalFeature}` experimental feature](@docroot@/contributing/experimental-features.md#xp-feature-${experimentalFeature})
+          > is enabled.
+          > For example, include the following in [`nix.conf`](@docroot@/command-ref/conf-file.md):
+          >
+          > ```
+          > extra-experimental-features = ${experimentalFeature}
+          > ${setting} = ...
+          > ```
         '';
 
       showDefault = documentDefault: defaultValue:

doc/manual/generate-store-info.nix

@@ -1,45 +1,57 @@
 let
-  inherit (builtins) attrValues mapAttrs;
-  inherit (import ./utils.nix) concatStrings optionalString;
-  showSettings = import ./generate-settings.nix;
+  inherit (builtins) attrNames listToAttrs concatStringsSep readFile replaceStrings;
+  inherit (import <nix/utils.nix>) optionalString filterAttrs trim squash toLower unique indent;
+  showSettings = import <nix/generate-settings.nix>;
 in
 
-inlineHTML: storesInfo:
+{
+  # data structure describing all stores and their parameters
+  storeInfo,
+  # whether to add inline HTML tags
+  # `lowdown` does not eat those for one of the output modes
+  inlineHTML,
+}:
 
 let
 
-  showStore = name: { settings, doc, experimentalFeature }:
+  showStore = { name, slug }: { settings, doc, experimentalFeature }:
     let
-
-    result = ''
-      ## ${name}
-
-      ${doc}
+      result = squash ''
+        # ${name}
 
         ${experimentalFeatureNote}
 
-      ### Settings
+        ${doc}
+
+        ## Settings
 
         ${showSettings { prefix = "store-${slug}"; inherit inlineHTML; } settings}
       '';
 
-      # markdown doesn't like spaces in URLs
-      slug = builtins.replaceStrings [ " " ] [ "-" ] name;
-
       experimentalFeatureNote = optionalString (experimentalFeature != null) ''
         > **Warning**
+        >
         > This store is part of an
         > [experimental feature](@docroot@/contributing/experimental-features.md).
-
-      To use this store, you need to make sure the corresponding experimental feature,
-      [`${experimentalFeature}`](@docroot@/contributing/experimental-features.md#xp-feature-${experimentalFeature}),
-      is enabled.
-      For example, include the following in [`nix.conf`](#):
-
-      ```
-      extra-experimental-features = ${experimentalFeature}
-      ```
+        >
+        > To use this store, make sure the
+        > [`${experimentalFeature}` experimental feature](@docroot@/contributing/experimental-features.md#xp-feature-${experimentalFeature})
+        > is enabled.
+        > For example, include the following in [`nix.conf`](@docroot@/command-ref/conf-file.md):
+        >
+        > ```
+        > extra-experimental-features = ${experimentalFeature}
+        > ```
       '';
     in result;
 
-in concatStrings (attrValues (mapAttrs showStore storesInfo))
+  storesList = map
+    (name: rec {
+      inherit name;
+      slug = replaceStrings [ " " ] [ "-" ] (toLower name);
+      filename = "${slug}.md";
+      page = showStore { inherit name slug; } storeInfo.${name};
+    })
+    (attrNames storeInfo);
+
+in storesList

doc/manual/generate-store-types.nix

@@ -0,0 +1,39 @@
+let
+  inherit (builtins) attrNames listToAttrs concatStringsSep readFile replaceStrings;
+  showSettings = import <nix/generate-settings.nix>;
+  showStoreDocs = import <nix/generate-store-info.nix>;
+in
+
+storeInfo:
+
+let
+  storesList = showStoreDocs {
+    inherit storeInfo;
+    inlineHTML = true;
+  };
+
+  index =
+    let
+      showEntry = store:
+        "- [${store.name}](./${store.filename})";
+    in
+    concatStringsSep "\n" (map showEntry storesList);
+
+  "index.md" = replaceStrings
+    [ "@store-types@" ] [ index ]
+    (readFile ./src/store/types/index.md.in);
+
+  tableOfContents =
+    let
+      showEntry = store:
+        "    - [${store.name}](store/types/${store.filename})";
+    in
+    concatStringsSep "\n" (map showEntry storesList) + "\n";
+
+  "SUMMARY.md" = tableOfContents;
+
+  storePages = listToAttrs
+    (map (s: { name = s.filename; value = s.page; }) storesList);
+
+in
+storePages // { inherit "index.md" "SUMMARY.md"; }

doc/manual/generate-xp-features-shortlist.nix

@@ -1,5 +1,5 @@
 with builtins;
-with import ./utils.nix;
+with import <nix/utils.nix>;
 
 let
   showExperimentalFeature = name: doc:

doc/manual/generate-xp-features.nix

@@ -1,5 +1,5 @@
 with builtins;
-with import ./utils.nix;
+with import <nix/utils.nix>;
 
 let
   showExperimentalFeature = name: doc:
@@ -8,4 +8,6 @@ let
 
       ${doc}
     '';
-in xps: (concatStringsSep "\n" (attrValues (mapAttrs showExperimentalFeature xps)))
+in
+
+xps: (concatStringsSep "\n" (attrValues (mapAttrs showExperimentalFeature xps)))

doc/manual/local.mk

@@ -1,5 +1,10 @@
 ifeq ($(doc_generate),yes)
 
+# The version of Nix used to generate the doc. Can also be
+# `$(nix_INSTALL_PATH)` or just `nix` (to grap ambient from the `PATH`),
+# if one prefers.
+doc_nix = $(nix_PATH)
+
 MANUAL_SRCS := \
 	$(call rwildcard, $(d)/src, *.md) \
 	$(call rwildcard, $(d)/src, */*.md)
@@ -32,7 +37,7 @@ dummy-env = env -i \
 	NIX_STATE_DIR=/dummy \
 	NIX_CONFIG='cores = 0'
 
-nix-eval = $(dummy-env) $(bindir)/nix eval --experimental-features nix-command -I nix=doc/manual --store dummy:// --impure --raw
+nix-eval = $(dummy-env) $(doc_nix) eval --experimental-features nix-command -I nix=doc/manual --store dummy:// --impure --raw
 
 # re-implement mdBook's include directive to make it usable for terminal output and for proper @docroot@ substitution
 define process-includes
@@ -92,56 +97,63 @@ $(d)/nix-profiles.5: $(d)/src/command-ref/files/profiles.md
 	$(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/SUMMARY-rl-next.md $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md
+$(d)/src/SUMMARY.md: $(d)/src/SUMMARY.md.in $(d)/src/SUMMARY-rl-next.md $(d)/src/store/types $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md
 	@cp $< $@
 	@$(call process-includes,$@,$@)
 
-$(d)/src/command-ref/new-cli: $(d)/nix.json $(d)/utils.nix $(d)/generate-manpage.nix $(d)/generate-settings.nix $(d)/generate-store-info.nix $(bindir)/nix
+$(d)/src/store/types: $(d)/nix.json $(d)/utils.nix $(d)/generate-store-info.nix  $(d)/generate-store-types.nix $(d)/src/store/types/index.md.in $(doc_nix)
+	@# FIXME: build out of tree!
+	@rm -rf $@.tmp
+	$(trace-gen) $(nix-eval) --write-to $@.tmp --expr 'import doc/manual/generate-store-types.nix (builtins.fromJSON (builtins.readFile $<)).stores'
+	@# do not destroy existing contents
+	@mv $@.tmp/* $@/
+
+$(d)/src/command-ref/new-cli: $(d)/nix.json $(d)/utils.nix $(d)/generate-manpage.nix $(d)/generate-settings.nix $(d)/generate-store-info.nix $(doc_nix)
 	@rm -rf $@ $@.tmp
 	$(trace-gen) $(nix-eval) --write-to $@.tmp --expr 'import doc/manual/generate-manpage.nix true (builtins.readFile $<)'
 	@mv $@.tmp $@
 
-$(d)/src/command-ref/conf-file.md: $(d)/conf-file.json $(d)/utils.nix $(d)/generate-settings.nix $(d)/src/command-ref/conf-file-prefix.md $(d)/src/command-ref/experimental-features-shortlist.md $(bindir)/nix
+$(d)/src/command-ref/conf-file.md: $(d)/conf-file.json $(d)/utils.nix $(d)/generate-settings.nix $(d)/src/command-ref/conf-file-prefix.md $(d)/src/command-ref/experimental-features-shortlist.md $(doc_nix)
 	@cat doc/manual/src/command-ref/conf-file-prefix.md > $@.tmp
 	$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-settings.nix { prefix = "conf"; } (builtins.fromJSON (builtins.readFile $<))' >> $@.tmp;
 	@mv $@.tmp $@
 
-$(d)/nix.json: $(bindir)/nix
-	$(trace-gen) $(dummy-env) $(bindir)/nix __dump-cli > $@.tmp
+$(d)/nix.json: $(doc_nix)
+	$(trace-gen) $(dummy-env) $(doc_nix) __dump-cli > $@.tmp
 	@mv $@.tmp $@
 
-$(d)/conf-file.json: $(bindir)/nix
-	$(trace-gen) $(dummy-env) $(bindir)/nix config show --json --experimental-features nix-command > $@.tmp
+$(d)/conf-file.json: $(doc_nix)
+	$(trace-gen) $(dummy-env) $(doc_nix) config show --json --experimental-features nix-command > $@.tmp
 	@mv $@.tmp $@
 
-$(d)/src/contributing/experimental-feature-descriptions.md: $(d)/xp-features.json $(d)/utils.nix $(d)/generate-xp-features.nix $(bindir)/nix
+$(d)/src/contributing/experimental-feature-descriptions.md: $(d)/xp-features.json $(d)/utils.nix $(d)/generate-xp-features.nix $(doc_nix)
 	@rm -rf $@ $@.tmp
 	$(trace-gen) $(nix-eval) --write-to $@.tmp --expr 'import doc/manual/generate-xp-features.nix (builtins.fromJSON (builtins.readFile $<))'
 	@mv $@.tmp $@
 
-$(d)/src/command-ref/experimental-features-shortlist.md: $(d)/xp-features.json $(d)/utils.nix $(d)/generate-xp-features-shortlist.nix $(bindir)/nix
+$(d)/src/command-ref/experimental-features-shortlist.md: $(d)/xp-features.json $(d)/utils.nix $(d)/generate-xp-features-shortlist.nix $(doc_nix)
 	@rm -rf $@ $@.tmp
 	$(trace-gen) $(nix-eval) --write-to $@.tmp --expr 'import doc/manual/generate-xp-features-shortlist.nix (builtins.fromJSON (builtins.readFile $<))'
 	@mv $@.tmp $@
 
-$(d)/xp-features.json: $(bindir)/nix
-	$(trace-gen) $(dummy-env) $(bindir)/nix __dump-xp-features > $@.tmp
+$(d)/xp-features.json: $(doc_nix)
+	$(trace-gen) $(dummy-env) $(doc_nix) __dump-xp-features > $@.tmp
 	@mv $@.tmp $@
 
-$(d)/src/language/builtins.md: $(d)/language.json $(d)/generate-builtins.nix $(d)/src/language/builtins-prefix.md $(bindir)/nix
+$(d)/src/language/builtins.md: $(d)/language.json $(d)/generate-builtins.nix $(d)/src/language/builtins-prefix.md $(doc_nix)
 	@cat doc/manual/src/language/builtins-prefix.md > $@.tmp
 	$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-builtins.nix (builtins.fromJSON (builtins.readFile $<)).builtins' >> $@.tmp;
 	@cat doc/manual/src/language/builtins-suffix.md >> $@.tmp
 	@mv $@.tmp $@
 
-$(d)/src/language/builtin-constants.md: $(d)/language.json $(d)/generate-builtin-constants.nix $(d)/src/language/builtin-constants-prefix.md $(bindir)/nix
+$(d)/src/language/builtin-constants.md: $(d)/language.json $(d)/generate-builtin-constants.nix $(d)/src/language/builtin-constants-prefix.md $(doc_nix)
 	@cat doc/manual/src/language/builtin-constants-prefix.md > $@.tmp
 	$(trace-gen) $(nix-eval) --expr 'import doc/manual/generate-builtin-constants.nix (builtins.fromJSON (builtins.readFile $<)).constants' >> $@.tmp;
 	@cat doc/manual/src/language/builtin-constants-suffix.md >> $@.tmp
 	@mv $@.tmp $@
 
-$(d)/language.json: $(bindir)/nix
-	$(trace-gen) $(dummy-env) $(bindir)/nix __dump-language > $@.tmp
+$(d)/language.json: $(doc_nix)
+	$(trace-gen) $(dummy-env) $(doc_nix) __dump-language > $@.tmp
 	@mv $@.tmp $@
 
 # Generate "Upcoming release" notes (or clear it and remove from menu)
@@ -195,7 +207,7 @@ doc/manual/generated/man1/nix3-manpages: $(d)/src/command-ref/new-cli
 # `@docroot@` is to be preserved for documenting the mechanism
 # FIXME: maybe contributing guides should live right next to the code
 # instead of in the manual
-$(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/contributing/experimental-feature-descriptions.md $(d)/src/command-ref/conf-file.md $(d)/src/language/builtins.md $(d)/src/language/builtin-constants.md $(d)/src/release-notes/rl-next.md
+$(docdir)/manual/index.html: $(MANUAL_SRCS) $(d)/book.toml $(d)/anchors.jq $(d)/custom.css $(d)/src/SUMMARY.md $(d)/src/store/types $(d)/src/command-ref/new-cli $(d)/src/contributing/experimental-feature-descriptions.md $(d)/src/command-ref/conf-file.md $(d)/src/language/builtins.md $(d)/src/language/builtin-constants.md $(d)/src/release-notes/rl-next.md
 	$(trace-gen) \
 		tmp="$$(mktemp -d)"; \
 		cp -r doc/manual "$$tmp"; \

doc/manual/rl-next/allowed-uris-can-now-match-whole-schemes.md

@@ -0,0 +1,7 @@
+---
+synopsis: Option `allowed-uris` can now match whole schemes in URIs without slashes
+prs: 9547
+---
+
+If a scheme, such as `github:` is specified in the `allowed-uris` option, all URIs starting with `github:` are allowed.
+Previously this only worked for schemes whose URIs used the `://` syntax.

doc/manual/rl-next/cgroup-stats.md

@@ -0,0 +1,8 @@
+---
+synopsis: Include cgroup stats when building through the daemon
+prs: 9598
+---
+
+Nix now also reports cgroup statistics when building through the nix daemon and when doing remote builds using ssh-ng,
+if both sides of the connection are this version of Nix or newer. 
+

doc/manual/rl-next/hash-format-nix32.md

@@ -0,0 +1,23 @@
+---
+synopsis: Rename hash format `base32` to `nix32`
+prs: 9452
+---
+
+Hash format `base32` was renamed to `nix32` since it used a special nix-specific character set for 
+[Base32](https://en.wikipedia.org/wiki/Base32).
+
+## Deprecation: Use `nix32` instead of `base32` as `toHashFormat`
+
+For the builtin `convertHash`, the `toHashFormat` parameter now accepts the same hash formats as the `--to`/`--from`
+parameters of the `nix hash conert` command: `"base16"`, `"nix32"`, `"base64"`, and `"sri"`. The former `"base32"` value
+remains as a deprecated alias for `"base32"`. Please convert your code from:
+
+```nix
+builtins.convertHash { inherit hash hashAlgo; toHashFormat = "base32";}
+```
+
+to
+
+```nix
+builtins.convertHash { inherit hash hashAlgo; toHashFormat = "nix32";}
+```

doc/manual/rl-next/mounted-ssh-store.md

@@ -1,9 +1,8 @@
+---
 synopsis: Mounted SSH Store
-issues: #7890
-prs: #7912
-description: {
+issues: 7890
+prs: 7912
+---
 
 Introduced the store [`mounted-ssh-ng://`](@docroot@/command-ref/new-cli/nix3-help-stores.md).
 This store allows full access to a Nix store on a remote machine and additionally requires that the store be mounted in the local filesystem.
-
-}

doc/manual/rl-next/nix-config-show.md

@@ -1,8 +1,7 @@
-synopsis: `nix config show`
-issues: #7672
-prs: #9477
-description: {
+---
+synopsis: Rename to `nix config show`
+issues: 7672
+prs: 9477
+---
 
-`nix show-config` was renamed to `nix config show` to be more consistent with the rest of the command-line interface.
-
-}
+`nix show-config` was renamed to `nix config show`, and `nix doctor` was renamed to `nix config check`, to be more consistent with the rest of the command-line interface.

doc/manual/rl-next/nix-env-json-drv-path.md

@@ -1,9 +1,6 @@
+---
 synopsis: Fix `nix-env --query --drv-path --json`
-prs: #9257
-description: {
+prs: 9257
+---
 
 Fixed a bug where `nix-env --query` ignored `--drv-path` when `--json` was set.
-
-}
-
-

doc/manual/rl-next/nix-hash-convert.md

@@ -0,0 +1,47 @@
+---
+synopsis: Add `nix hash convert`
+prs: 9452
+---
+
+New [`nix hash convert`](https://github.com/NixOS/nix/issues/8876) sub command with a fast track
+to stabilization! Examples:
+
+- Convert the hash to `nix32`.
+
+  ```bash
+  $ nix hash convert --algo "sha1" --to nix32 "800d59cfcd3c05e900cb4e214be48f6b886a08df"
+  vw46m23bizj4n8afrc0fj19wrp7mj3c0
+  ```
+  `nix32` is a base32 encoding with a nix-specific character set.
+  Explicitly specify the hashing algorithm (optional with SRI hashes) but detect hash format by the length of the input
+  hash.
+- Convert the hash to the `sri` format that includes an algorithm specification:
+  ```bash
+  nix hash convert --algo "sha1" "800d59cfcd3c05e900cb4e214be48f6b886a08df"
+  sha1-gA1Zz808BekAy04hS+SPa4hqCN8=
+  ```
+  or with an explicit `-to` format:
+  ```bash
+  nix hash convert --algo "sha1" --to sri "800d59cfcd3c05e900cb4e214be48f6b886a08df"
+  sha1-gA1Zz808BekAy04hS+SPa4hqCN8=
+  ```
+- Assert the input format of the hash:
+  ```bash
+  nix hash convert --algo "sha256" --from nix32 "ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0="
+  error: input hash 'ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0=' does not have the expected format '--from nix32'
+  nix hash convert --algo "sha256" --from nix32 "1b8m03r63zqhnjf7l5wnldhh7c134ap5vpj0850ymkq1iyzicy5s"
+  sha256-ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0=
+  ```
+
+The `--to`/`--from`/`--algo` parameters have context-sensitive auto-completion.
+
+## Related Deprecations
+
+The following commands are still available but will emit a deprecation warning. Please convert your code to
+`nix hash convert`:
+
+- `nix hash to-base16 $hash1 $hash2`: Use `nix hash convert --to base16 $hash1 $hash2` instead.
+- `nix hash to-base32 $hash1 $hash2`: Use `nix hash convert --to nix32 $hash1 $hash2` instead.
+- `nix hash to-base64 $hash1 $hash2`: Use `nix hash convert --to base64 $hash1 $hash2` instead.
+- `nix hash to-sri $hash1 $hash2`: : Use `nix hash convert --to sri $hash1 $hash2`
+  or even just `nix hash convert $hash1 $hash2` instead.

doc/manual/rl-next/source-positions-in-errors.md

@@ -0,0 +1,42 @@
+---
+synopsis: Source locations are printed more consistently in errors
+issues: 561
+prs: 9555
+---
+
+Source location information is now included in error messages more
+consistently. Given this code:
+
+```nix
+let
+  attr = {foo = "bar";};
+  key = {};
+in
+  attr.${key}
+```
+
+Previously, Nix would show this unhelpful message when attempting to evaluate
+it:
+
+```
+error:
+       … while evaluating an attribute name
+
+       error: value is a set while a string was expected
+```
+
+Now, the error message displays where the problematic value was found:
+
+```
+error:
+       … while evaluating an attribute name
+
+         at bad.nix:4:11:
+
+            3|   key = {};
+            4| in attr.${key}
+             |           ^
+            5|
+
+       error: value is a set while a string was expected
+```

doc/manual/src/SUMMARY.md.in

@@ -2,7 +2,7 @@
 
 - [Introduction](introduction.md)
 - [Quick Start](quick-start.md)
-- [Installation](installation/installation.md)
+- [Installation](installation/index.md)
   - [Supported Platforms](installation/supported-platforms.md)
   - [Installing a Binary Distribution](installation/installing-binary.md)
   - [Installing Nix from Source](installation/installing-source.md)
@@ -20,6 +20,8 @@
   - [File System Object](store/file-system-object.md)
   - [Store Object](store/store-object.md)
   - [Store Path](store/store-path.md)
+  - [Store Types](store/types/index.md)
+{{#include ./store/types/SUMMARY.md}}
 - [Nix Language](language/index.md)
   - [Data Types](language/values.md)
   - [Language Constructs](language/constructs.md)
@@ -31,11 +33,11 @@
     - [Import From Derivation](language/import-from-derivation.md)
   - [Built-in Constants](language/builtin-constants.md)
   - [Built-in Functions](language/builtins.md)
-- [Package Management](package-management/package-management.md)
+- [Package Management](package-management/index.md)
   - [Profiles](package-management/profiles.md)
   - [Garbage Collection](package-management/garbage-collection.md)
     - [Garbage Collector Roots](package-management/garbage-collector-roots.md)
-- [Advanced Topics](advanced-topics/advanced-topics.md)
+- [Advanced Topics](advanced-topics/index.md)
   - [Sharing Packages Between Machines](package-management/sharing-packages.md)
     - [Serving a Nix store via HTTP](package-management/binary-cache-substituter.md)
     - [Copying Closures via SSH](package-management/copy-closure.md)
@@ -45,7 +47,7 @@
   - [Tuning Cores and Jobs](advanced-topics/cores-vs-jobs.md)
   - [Verifying Build Reproducibility](advanced-topics/diff-hook.md)
   - [Using the `post-build-hook`](advanced-topics/post-build-hook.md)
-- [Command Reference](command-ref/command-ref.md)
+- [Command Reference](command-ref/index.md)
   - [Common Options](command-ref/opt-common.md)
   - [Common Environment Variables](command-ref/env-common.md)
   - [Main Commands](command-ref/main-commands.md)
@@ -102,18 +104,18 @@
     - [Channels](command-ref/files/channels.md)
     - [Default Nix expression](command-ref/files/default-nix-expression.md)
 - [Architecture and Design](architecture/architecture.md)
-- [Protocols](protocols/protocols.md)
+- [Protocols](protocols/index.md)
   - [Serving Tarball Flakes](protocols/tarball-fetcher.md)
   - [Derivation "ATerm" file format](protocols/derivation-aterm.md)
 - [Glossary](glossary.md)
-- [Contributing](contributing/contributing.md)
+- [Contributing](contributing/index.md)
   - [Hacking](contributing/hacking.md)
   - [Testing](contributing/testing.md)
   - [Documentation](contributing/documentation.md)
   - [Experimental Features](contributing/experimental-features.md)
   - [CLI guideline](contributing/cli-guideline.md)
   - [C++ style guide](contributing/cxx.md)
-- [Release Notes](release-notes/release-notes.md)
+- [Release Notes](release-notes/index.md)
 {{#include ./SUMMARY-rl-next.md}}
   - [Release 2.19 (2023-11-17)](release-notes/rl-2.19.md)
   - [Release 2.18 (2023-09-20)](release-notes/rl-2.18.md)

doc/manual/src/architecture/architecture.md

@@ -52,7 +52,7 @@ The following [concept map] shows its main components (rectangles), the objects
                                             '---------------'
 ```
 
-At the top is the [command line interface](../command-ref/command-ref.md) that drives the underlying layers.
+At the top is the [command line interface](../command-ref/index.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*.
 

doc/manual/src/contributing/cli-guideline.md

@@ -87,7 +87,7 @@ impacted the most by bad user experience.
       and [aligning of text](#text-alignment).
     - [Autocomplete](#shell-completion) of options.
 
-  Examples of such commands: `nix doctor`, `nix edit`, `nix eval`, ...
+  Examples of such commands: `nix edit`, `nix eval`, ...
 
 - **Utility and scripting commands**
 
@@ -426,7 +426,7 @@ This leads to the following guidelines:
 ### Examples
 
 
-This is bad, because all keys must be assumed to be store implementations:
+This is bad, because all keys must be assumed to be store types:
 
 ```json
 {

doc/manual/src/contributing/hacking.md

@@ -10,7 +10,7 @@ $ cd nix
 
 The following instructions assume you already have some version of Nix installed locally, so that you can use it to set up the development environment. If you don't have it installed, follow the [installation instructions].
 
-[installation instructions]: ../installation/installation.md
+[installation instructions]: ../installation/index.md
 
 ## Building Nix with flakes
 
@@ -146,6 +146,31 @@ $ nix build .#packages.aarch64-linux.default
 Cross-compiled builds are available for ARMv6 (`armv6l-linux`) and ARMv7 (`armv7l-linux`).
 Add more [system types](#system-type) to `crossSystems` in `flake.nix` to bootstrap Nix on unsupported platforms.
 
+### Building for multiple platforms at once
+
+It is useful to perform multiple cross and native builds on the same source tree,
+for example to ensure that better support for one platform doesn't break the build for another.
+In order to facilitate this, Nix has some support for being built out of tree – that is, placing build artefacts in a different directory than the source code:
+
+1. Create a directory for the build, e.g.
+
+   ```bash
+   mkdir build
+   ```
+
+2. Run the configure script from that directory, e.g.
+
+   ```bash
+   cd build
+   ../configure <configure flags>
+   ```
+
+3. Run make from the source directory, but with the build directory specified, e.g.
+
+   ```bash
+   make builddir=build <make flags>
+   ```
+
 ## System type
 
 Nix uses a string with he following format to identify the *system type* or *platform* it runs on:
@@ -232,17 +257,16 @@ User-visible changes should come with a release note.
 Here's what a complete entry looks like. The file name is not incorporated in the document.
 
 ```
+---
 synopsis: Basically a title
-issues: #1234
-prs: #1238
-description: {
+issues: 1234
+prs: 1238
+---
 
 Here's one or more paragraphs that describe the change.
 
 - It's markdown
 - Add references to the manual using @docroot@
-
-}
 ```
 
 Significant changes should add the following header, which moves them to the top.
@@ -258,3 +282,45 @@ See also the [format documentation](https://github.com/haskell/cabal/blob/master
 
 Releases have a precomputed `rl-MAJOR.MINOR.md`, and no `rl-next.md`.
 Set `buildUnreleasedNotes = true;` in `flake.nix` to build the release notes on the fly.
+
+## Branches
+
+- [`master`](https://github.com/NixOS/nix/commits/master)
+
+  The main development branch. All changes are approved and merged here.
+  When developing a change, create a branch based on the latest `master`.
+
+  Maintainers try to [keep it in a release-worthy state](#reverting).
+
+- [`maintenance-*.*`](https://github.com/NixOS/nix/branches/all?query=maintenance)
+
+  These branches are the subject of backports only, and are
+  also [kept](#reverting) in a release-worthy state.
+
+  See [`maintainers/backporting.md`](https://github.com/NixOS/nix/blob/master/maintainers/backporting.md)
+
+- [`latest-release`](https://github.com/NixOS/nix/tree/latest-release)
+
+  The latest patch release of the latest minor version.
+
+  See [`maintainers/release-process.md`](https://github.com/NixOS/nix/blob/master/maintainers/release-process.md)
+
+- [`backport-*-to-*`](https://github.com/NixOS/nix/branches/all?query=backport)
+
+  Generally branches created by the backport action.
+
+  See [`maintainers/backporting.md`](https://github.com/NixOS/nix/blob/master/maintainers/backporting.md)
+
+- [_other_](https://github.com/NixOS/nix/branches/all)
+
+  Branches that do not conform to the above patterns should be feature branches.
+
+## Reverting
+
+If a change turns out to be merged by mistake, or contain a regression, it may be reverted.
+A revert is not a rejection of the contribution, but merely part of an effective development process.
+It makes sure that development keeps running smoothly, with minimal uncertainty, and less overhead.
+If maintainers have to worry too much about avoiding reverts, they would not be able to merge as much.
+By embracing reverts as a good part of the development process, everyone wins.
+
+However, taking a step back may be frustrating, so maintainers will be extra supportive on the next try.

doc/manual/src/contributing/testing.md

@@ -20,6 +20,7 @@ The unit tests are defined using the [googletest] and [rapidcheck] frameworks.
 
 [googletest]: https://google.github.io/googletest/
 [rapidcheck]: https://github.com/emil-e/rapidcheck
+[property testing]: https://en.wikipedia.org/wiki/Property_testing
 
 ### Source and header layout
 
@@ -28,34 +29,50 @@ The unit tests are defined using the [googletest] and [rapidcheck] frameworks.
 > ```
 > src
 > ├── libexpr
+> │   ├── local.mk
 > │   ├── value/context.hh
 > │   ├── value/context.cc
-> │   │
-> │   …
->     └── tests
-> │       ├── value/context.hh
-> │       ├── value/context.cc
-> │       │
 > │   …
 > │
-> ├── unit-test-data
-> │   ├── libstore
-> │   │   ├── worker-protocol/content-address.bin
+> ├── tests
+> │   │
+> │   …
+> │   └── unit
+> │       ├── libutil
+> │       │   ├── local.mk
 > │       │   …
+> │       │   └── data
+> │       │       ├── git/tree.txt
+> │       │       …
+> │       │
+> │       ├── libexpr-support
+> │       │   ├── local.mk
+> │       │   └── tests
+> │       │       ├── value/context.hh
+> │       │       ├── value/context.cc
+> │       │       …
+> │       │
+> │       ├── libexpr
+> │       …   ├── local.mk
+> │           ├── value/context.cc
 > │           …
 > …
 > ```
 
-The unit tests for each Nix library (`libnixexpr`, `libnixstore`, etc..) live inside a directory `src/${library_shortname}/tests` within the directory for the library (`src/${library_shortname}`).
+The tests for each Nix library (`libnixexpr`, `libnixstore`, etc..) live inside a directory `tests/unit/${library_name_without-nix}`.
+Given a interface (header) and implementation pair in the original library, say, `src/libexpr/value/context.{hh,cc}`, we write tests for it in `tests/unit/libexpr/tests/value/context.cc`, and (possibly) declare/define additional interfaces for testing purposes in `tests/unit/libexpr-support/tests/value/context.{hh,cc}`.
 
-The data is in `unit-test-data`, with one subdir per library, with the same name as where the code goes.
-For example, `libnixstore` code is in `src/libstore`, and its test data is in `unit-test-data/libstore`.
-The path to the `unit-test-data` directory is passed to the unit test executable with the environment variable `_NIX_TEST_UNIT_DATA`.
+Data for unit tests is stored in a `data` subdir of the directory for each unit test executable.
+For example, `libnixstore` code is in `src/libstore`, and its test data is in `tests/unit/libstore/data`.
+The path to the `tests/unit/data` directory is passed to the unit test executable with the environment variable `_NIX_TEST_UNIT_DATA`.
+Note that each executable only gets the data for its tests.
 
-> **Note**
-> Due to the way googletest works, downstream unit test executables will actually include and re-run upstream library tests.
-> Therefore it is important that the same value for `_NIX_TEST_UNIT_DATA` be used with the tests for each library.
-> That is why we have the test data nested within a single `unit-test-data` directory.
+The unit test libraries are in `tests/unit/${library_name_without-nix}-lib`.
+All headers are in a `tests` subdirectory so they are included with `#include "tests/"`.
+
+The use of all these separate directories for the unit tests might seem inconvenient, as for example the tests are not "right next to" the part of the code they are testing.
+But organizing the tests this way has one big benefit:
+there is no risk of any build-system wildcards for the library accidentally picking up test code that should not built and installed as part of the library.
 
 ### Running tests
 
@@ -69,7 +86,7 @@ See [functional characterisation testing](#characterisation-testing-functional)
 Like with the functional characterisation, `_NIX_TEST_ACCEPT=1` is also used.
 For example:
 ```shell-session
-$ _NIX_TEST_ACCEPT=1 make libstore-tests-exe_RUN
+$ _NIX_TEST_ACCEPT=1 make libstore-tests_RUN
 ...
 [  SKIPPED ] WorkerProtoTest.string_read
 [  SKIPPED ] WorkerProtoTest.string_write
@@ -80,6 +97,18 @@ $ _NIX_TEST_ACCEPT=1 make libstore-tests-exe_RUN
 will regenerate the "golden master" expected result for the `libnixstore` characterisation tests.
 The characterisation tests will mark themselves "skipped" since they regenerated the expected result instead of actually testing anything.
 
+### Unit test support libraries
+
+There are headers and code which are not just used to test the library in question, but also downstream libraries.
+For example, we do [property testing] with the [rapidcheck] library.
+This requires writing `Arbitrary` "instances", which are used to describe how to generate values of a given type for the sake of running property tests.
+Because types contain other types, `Arbitrary` "instances" for some type are not just useful for testing that type, but also any other type that contains it.
+Downstream types frequently contain upstream types, so it is very important that we share arbitrary instances so that downstream libraries' property tests can also use them.
+
+It is important that these testing libraries don't contain any actual tests themselves.
+On some platforms they would be run as part of every test executable that uses them, which is redundant.
+On other platforms they wouldn't be run at all.
+
 ## Functional tests
 
 The functional tests reside under the `tests/functional` directory and are listed in `tests/functional/local.mk`.

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

@@ -257,29 +257,18 @@ Derivations can declare some infrequently used optional attributes.
     of the environment (typically, a few hundred kilobyte).
 
   - [`preferLocalBuild`]{#adv-attr-preferLocalBuild}\
-    If this attribute is set to `true` and [distributed building is
-    enabled](../advanced-topics/distributed-builds.md), then, if
-    possible, the derivation will be built locally instead of forwarded
-    to a remote machine. This is appropriate for trivial builders
-    where the cost of doing a download or remote build would exceed
-    the cost of building locally.
+    If this attribute is set to `true` and [distributed building is enabled](../advanced-topics/distributed-builds.md), then, if possible, the derivation will be built locally instead of being forwarded to a remote machine.
+    This is useful for derivations that are cheapest to build locally.
 
   - [`allowSubstitutes`]{#adv-attr-allowSubstitutes}\
-    If this attribute is set to `false`, then Nix will always build this
-    derivation; it will not try to substitute its outputs. This is
-    useful for very trivial derivations (such as `writeText` in Nixpkgs)
-    that are cheaper to build than to substitute from a binary cache.
+    If this attribute is set to `false`, then Nix will always build this derivation (locally or remotely); it will not try to substitute its outputs.
+    This is useful for derivations that are cheaper to build than to substitute.
 
-    You may disable the effects of this attibute by enabling the
-    `always-allow-substitutes` configuration option in Nix.
+    This attribute can be ignored by setting [`always-allow-substitutes`](@docroot@/command-ref/conf-file.md#conf-always-allow-substitutes) to `true`.
 
     > **Note**
     >
-    > You need to have a builder configured which satisfies the
-    > derivation’s `system` attribute, since the derivation cannot be
-    > substituted. Thus it is usually a good idea to align `system` with
-    > `builtins.currentSystem` when setting `allowSubstitutes` to
-    > `false`. For most trivial derivations this should be the case.
+    > If set to `false`, the [`builder`](./derivations.md#attr-builder) should be able to run on the system type specified in the [`system` attribute](./derivations.md#attr-system), since the derivation cannot be substituted.
 
   - [`__structuredAttrs`]{#adv-attr-structuredAttrs}\
     If the special attribute `__structuredAttrs` is set to `true`, the other derivation

doc/manual/src/quick-start.md

@@ -1,10 +1,9 @@
 # Quick Start
 
-This chapter is for impatient people who don't like reading
-documentation.  For more in-depth information you are kindly referred
-to subsequent chapters.
+This chapter is for impatient people who don't like reading documentation.
+For more in-depth information you are kindly referred to subsequent chapters.
 
-1. Install Nix by running the following:
+1. Install Nix:
 
    ```console
    $ curl -L https://nixos.org/nix/install | sh
@@ -13,87 +12,33 @@ to subsequent chapters.
    The install script will use `sudo`, so make sure you have sufficient rights.
    On Linux, `--daemon` can be omitted for a single-user install.
 
-   For other installation methods, see [here](installation/installation.md).
+   For other installation methods, see the detailed [installation instructions](installation/index.md).
 
-1. See what installable packages are currently available in the
-   channel:
+1. Run software without installing it permanently:
 
    ```console
-   $ nix-env --query --available --attr-path
-   nixpkgs.docbook_xml_dtd_43                    docbook-xml-4.3
-   nixpkgs.docbook_xml_dtd_45                    docbook-xml-4.5
-   nixpkgs.firefox                               firefox-33.0.2
-   nixpkgs.hello                                 hello-2.9
-   nixpkgs.libxslt                               libxslt-1.1.28
-   …
+   $ nix-shell --packages cowsay lolcat
    ```
 
-1. Install some packages from the channel:
+   This downloads the specified packages with all their dependencies, and drops you into a Bash shell where the commands provided by those packages are present.
+   This will not affect your normal environment:
 
    ```console
-   $ nix-env --install --attr nixpkgs.hello
+   [nix-shell:~]$ cowsay Hello, Nix! | lolcat
    ```
 
-   This should download pre-built packages; it should not build them
-   locally (if it does, something went wrong).
-
-1. Test that they work:
+   Exiting the shell will make the programs disappear again:
 
    ```console
-   $ which hello
-   /home/eelco/.nix-profile/bin/hello
-   $ hello
-   Hello, world!
-   ```
-
-1. Uninstall a package:
-
-   ```console
-   $ nix-env --uninstall hello
-   ```
-
-1. You can also test a package without installing it:
-
-   ```console
-   $ nix-shell --packages hello
-   ```
-
-   This builds or downloads GNU Hello and its dependencies, then drops
-   you into a Bash shell where the `hello` command is present, all
-   without affecting your normal environment:
-
-   ```console
-   [nix-shell:~]$ hello
-   Hello, world!
-
    [nix-shell:~]$ exit
-
-   $ hello
-   hello: command not found
+   $ lolcat
+   lolcat: command not found
    ```
 
-1. To keep up-to-date with the channel, do:
+1. Search for more packages on <search.nixos.org> to try them out.
+
+1. Free up storage space:
 
    ```console
-   $ nix-channel --update nixpkgs
-   $ nix-env --upgrade '*'
-   ```
-
-   The latter command will upgrade each installed package for which
-   there is a “newer” version (as determined by comparing the version
-   numbers).
-
-1. If you're unhappy with the result of a `nix-env` action (e.g., an
-   upgraded package turned out not to work properly), you can go back:
-
-   ```console
-   $ nix-env --rollback
-   ```
-
-1. You should periodically run the Nix garbage collector to get rid of
-   unused packages, since uninstalls or upgrades don't actually delete
-   them:
-
-   ```console
-   $ nix-collect-garbage --delete-old
+   $ nix-collect-garbage
    ```

doc/manual/src/release-notes/rl-2.19.md

@@ -18,7 +18,7 @@
 - `nix-shell` shebang lines now support single-quoted arguments.
 
 - `builtins.fetchTree` is now its own experimental feature, [`fetch-tree`](@docroot@/contributing/experimental-features.md#xp-fetch-tree).
-  As described in the documentation for that feature, this is because we anticipate polishing it and then stabilizing it before the rest of flakes.
+  This allows stabilising it independently of the rest of what is encompassed by [`flakes`](@docroot@/contributing/experimental-features.md#xp-fetch-tree).
 
 - The interface for creating and updating lock files has been overhauled:
 

doc/manual/src/store/index.md

@@ -2,4 +2,4 @@
 
 The *Nix store* is an abstraction to store immutable file system data (such as software packages) that can have dependencies on other such data.
 
-There are multiple implementations of Nix stores with different capabilities, such as the actual filesystem (`/nix/store`) or binary caches.
+There are [multiple types of Nix stores](./types/index.md) with different capabilities, such as the default one on the [local filesystem](./types/local-store.md) (`/nix/store`) or [binary caches](./types/http-binary-cache-store.md).

doc/manual/src/store/types/index.md.in

@@ -1,6 +1,6 @@
-R"(
+Nix supports different types of stores:
 
-Nix supports different types of stores. These are described below.
+@store-types@
 
 ## Store URL format
 
@@ -29,18 +29,15 @@ supported settings for each store type are documented below.
 The special store URL `auto` causes Nix to automatically select a
 store as follows:
 
-* Use the [local store](#local-store) `/nix/store` if `/nix/var/nix`
+* Use the [local store](./local-store.md) `/nix/store` if `/nix/var/nix`
   is writable by the current user.
 
 * Otherwise, if `/nix/var/nix/daemon-socket/socket` exists, [connect
-  to the Nix daemon listening on that socket](#local-daemon-store).
+  to the Nix daemon listening on that socket](./local-daemon-store.md).
 
-* Otherwise, on Linux only, use the [local chroot store](#local-store)
+* Otherwise, on Linux only, use the [local chroot store](./local-store.md)
   `~/.local/share/nix/root`, which will be created automatically if it
   does not exist.
 
-* Otherwise, use the [local store](#local-store) `/nix/store`.
+* Otherwise, use the [local store](./local-store.md) `/nix/store`.
 
-@stores@
-
-)"

doc/manual/utils.nix

@@ -1,5 +1,11 @@
 with builtins;
 
+let
+  lowerChars = stringToCharacters "abcdefghijklmnopqrstuvwxyz";
+  upperChars = stringToCharacters "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+  stringToCharacters = s: genList (p: substring p 1 s) (stringLength s);
+in
+
 rec {
   splitLines = s: filter (x: !isList x) (split "\n" s);
 
@@ -18,6 +24,8 @@ rec {
     in
       if replaced == string then string else replaceStringsRec from to replaced;
 
+  toLower = replaceStrings upperChars lowerChars;
+
   squash = replaceStringsRec "\n\n\n" "\n\n";
 
   trim = string:

flake.lock

@@ -32,34 +32,18 @@
         "type": "github"
       }
     },
-    "lowdown-src": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1633514407,
-        "narHash": "sha256-Dw32tiMjdK9t3ETl5fzGrutQTzh2rufgZV4A/BbxuD4=",
-        "owner": "kristapsdz",
-        "repo": "lowdown",
-        "rev": "d2c2b44ff6c27b936ec27358a2653caaef8f73b8",
-        "type": "github"
-      },
-      "original": {
-        "owner": "kristapsdz",
-        "repo": "lowdown",
-        "type": "github"
-      }
-    },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1700748986,
-        "narHash": "sha256-/nqLrNU297h3PCw4QyDpZKZEUHmialJdZW2ceYFobds=",
+        "lastModified": 1701355166,
+        "narHash": "sha256-4V7XMI0Gd+y0zsi++cEHd99u3GNL0xSTGRmiWKzGnUQ=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "9ba29e2346bc542e9909d1021e8fd7d4b3f64db0",
+        "rev": "36c4ac09e9bebcec1fa7b7539cddb0c9e837409c",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-23.05-small",
+        "ref": "staging-23.05",
         "repo": "nixpkgs",
         "type": "github"
       }
@@ -84,7 +68,6 @@
       "inputs": {
         "flake-compat": "flake-compat",
         "libgit2": "libgit2",
-        "lowdown-src": "lowdown-src",
         "nixpkgs": "nixpkgs",
         "nixpkgs-regression": "nixpkgs-regression"
       }

flake.nix

@@ -1,17 +1,34 @@
 {
   description = "The purely functional package manager";
 
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.05-small";
+  # TODO Go back to nixos-23.05-small once
+  # https://github.com/NixOS/nixpkgs/pull/271202 is merged.
+  #
+  # Also, do not grab arbitrary further staging commits. This PR was
+  # carefully made to be based on release-23.05 and just contain
+  # rebuild-causing changes to packages that Nix actually uses.
+  #
+  # Once this is updated to something containing
+  # https://github.com/NixOS/nixpkgs/pull/271423, don't forget
+  # to remove the `nix.checkAllErrors = false;` line in the tests.
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/staging-23.05";
   inputs.nixpkgs-regression.url = "github:NixOS/nixpkgs/215d4d0fd80ca5163643b03a33fde804a29cc1e2";
-  inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
   inputs.flake-compat = { url = "github:edolstra/flake-compat"; flake = false; };
   inputs.libgit2 = { url = "github:libgit2/libgit2"; flake = false; };
 
-  outputs = { self, nixpkgs, nixpkgs-regression, lowdown-src, flake-compat, libgit2 }:
+  outputs = { self, nixpkgs, nixpkgs-regression, libgit2, ... }:
 
     let
       inherit (nixpkgs) lib;
 
+      # Experimental fileset library: https://github.com/NixOS/nixpkgs/pull/222981
+      # Not an "idiomatic" flake input because:
+      #  - Propagation to dependent locks: https://github.com/NixOS/nix/issues/7730
+      #  - Subflake would download redundant and huge parent flake
+      #  - No git tree hash support: https://github.com/NixOS/nix/issues/6044
+      inherit (import (builtins.fetchTarball { url = "https://github.com/NixOS/nix/archive/1bdcd7fc8a6a40b2e805bad759b36e64e911036b.tar.gz"; sha256 = "sha256:14ljlpdsp4x7h1fkhbmc4bd3vsqnx8zdql4h3037wh09ad6a0893"; }))
+        fileset;
+
       officialRelease = false;
 
       # Set to true to build the release notes for the next release.
@@ -30,11 +47,27 @@
       systems = linuxSystems ++ darwinSystems;
 
       crossSystems = [
-        "armv6l-linux" "armv7l-linux"
-        "x86_64-freebsd13" "x86_64-netbsd"
+        "armv6l-unknown-linux-gnueabihf"
+        "armv7l-unknown-linux-gnueabihf"
+        "x86_64-unknown-freebsd13"
+        "x86_64-unknown-netbsd"
       ];
 
-      stdenvs = [ "gccStdenv" "clangStdenv" "clang11Stdenv" "stdenv" "libcxxStdenv" "ccacheStdenv" ];
+      # Nix doesn't yet build on this platform, so we put it in a
+      # separate list. We just use this for `devShells` and
+      # `nixpkgsFor`, which this depends on.
+      shellCrossSystems = crossSystems ++ [
+        "x86_64-w64-mingw32"
+      ];
+
+      stdenvs = [
+        "ccacheStdenv"
+        "clang11Stdenv"
+        "clangStdenv"
+        "gccStdenv"
+        "libcxxStdenv"
+        "stdenv"
+      ];
 
       forAllSystems = lib.genAttrs systems;
 
@@ -49,57 +82,6 @@
             })
             stdenvs);
 
-      # Experimental fileset library: https://github.com/NixOS/nixpkgs/pull/222981
-      # Not an "idiomatic" flake input because:
-      #  - Propagation to dependent locks: https://github.com/NixOS/nix/issues/7730
-      #  - Subflake would download redundant and huge parent flake
-      #  - No git tree hash support: https://github.com/NixOS/nix/issues/6044
-      inherit (import (builtins.fetchTarball { url = "https://github.com/NixOS/nix/archive/1bdcd7fc8a6a40b2e805bad759b36e64e911036b.tar.gz"; sha256 = "sha256:14ljlpdsp4x7h1fkhbmc4bd3vsqnx8zdql4h3037wh09ad6a0893"; }))
-        fileset;
-
-      baseFiles =
-        # .gitignore has already been processed, so any changes in it are irrelevant
-        # at this point. It is not represented verbatim for test purposes because
-        # that would interfere with repo semantics.
-        fileset.fileFilter (f: f.name != ".gitignore") ./.;
-
-      configureFiles = fileset.unions [
-        ./.version
-        ./configure.ac
-        ./m4
-        # TODO: do we really need README.md? It doesn't seem used in the build.
-        ./README.md
-      ];
-
-      topLevelBuildFiles = fileset.unions [
-        ./local.mk
-        ./Makefile
-        ./Makefile.config.in
-        ./mk
-      ];
-
-      functionalTestFiles = fileset.unions [
-        ./tests/functional
-        (fileset.fileFilter (f: lib.strings.hasPrefix "nix-profile" f.name) ./scripts)
-      ];
-
-      nixSrc = fileset.toSource {
-        root = ./.;
-        fileset = fileset.intersect baseFiles (fileset.unions [
-          configureFiles
-          topLevelBuildFiles
-          ./boehmgc-coroutine-sp-fallback.diff
-          ./doc
-          ./misc
-          ./precompiled-headers.h
-          ./src
-          ./unit-test-data
-          ./COPYING
-          ./scripts/local.mk
-          functionalTestFiles
-        ]);
-      };
-
       # Memoize nixpkgs for different platforms for efficiency.
       nixpkgsFor = forAllSystems
         (system: let
@@ -108,8 +90,8 @@
               inherit system;
             };
             crossSystem = if crossSystem == null then null else {
-              system = crossSystem;
-            } // lib.optionalAttrs (crossSystem == "x86_64-freebsd13") {
+              config = crossSystem;
+            } // lib.optionalAttrs (crossSystem == "x86_64-unknown-freebsd13") {
               useLLVM = true;
             };
             overlays = [
@@ -121,17 +103,43 @@
         in {
           inherit stdenvs native;
           static = native.pkgsStatic;
-          cross = forAllCrossSystems (crossSystem: make-pkgs crossSystem "stdenv");
+          cross = lib.genAttrs shellCrossSystems (crossSystem: make-pkgs crossSystem "stdenv");
         });
 
-      commonDeps =
-        { pkgs
-        , isStatic ? pkgs.stdenv.hostPlatform.isStatic
-        }:
-        with pkgs; rec {
-        # Use "busybox-sandbox-shell" if present,
-        # if not (legacy) fallback and hope it's sufficient.
-        sh = pkgs.busybox-sandbox-shell or (busybox.override {
+      installScriptFor = tarballs:
+        nixpkgsFor.x86_64-linux.native.callPackage ./scripts/installer.nix {
+          inherit tarballs;
+        };
+
+      testNixVersions = pkgs: client: daemon:
+        pkgs.callPackage ./package.nix {
+          pname =
+            "nix-tests"
+            + lib.optionalString
+              (lib.versionAtLeast daemon.version "2.4pre20211005" &&
+               lib.versionAtLeast client.version "2.4pre20211005")
+              "-${client.version}-against-${daemon.version}";
+
+          inherit fileset;
+
+          test-client = client;
+          test-daemon = daemon;
+
+          doBuild = false;
+        };
+
+      binaryTarball = nix: pkgs: pkgs.callPackage ./scripts/binary-tarball.nix {
+        inherit nix;
+      };
+
+      overlayFor = getStdenv: final: prev:
+        let
+          stdenv = getStdenv final;
+        in
+        {
+          nixStable = prev.nix;
+
+          default-busybox-sandbox-shell = final.busybox.override {
             useMusl = true;
             enableStatic = true;
             enableMinimal = true;
@@ -153,380 +161,57 @@
               CONFIG_ASH_PRINTF y
               CONFIG_ASH_TEST y
             '';
-        });
+          };
 
-        configureFlags =
-          lib.optionals stdenv.isLinux [
-            "--with-boost=${boost-nix}/lib"
-            "--with-sandbox-shell=${sh}/bin/busybox"
-          ]
-          ++ lib.optionals (stdenv.isLinux && !(isStatic && stdenv.system == "aarch64-linux")) [
-            "LDFLAGS=-fuse-ld=gold"
-          ];
-
-        testConfigureFlags = [
-          "RAPIDCHECK_HEADERS=${lib.getDev rapidcheck}/extras/gtest/include"
-        ] ++ lib.optionals (stdenv.hostPlatform != stdenv.buildPlatform) [
-          "--enable-install-unit-tests"
-          "--with-check-bin-dir=${builtins.placeholder "check"}/bin"
-          "--with-check-lib-dir=${builtins.placeholder "check"}/lib"
-        ];
-
-        internalApiDocsConfigureFlags = [
-          "--enable-internal-api-docs"
-        ];
-
-        changelog-d = pkgs.buildPackages.changelog-d;
-
-        nativeBuildDeps =
-          [
-            buildPackages.bison
-            buildPackages.flex
-            (lib.getBin buildPackages.lowdown-nix)
-            buildPackages.mdbook
-            buildPackages.mdbook-linkcheck
-            buildPackages.autoconf-archive
-            buildPackages.autoreconfHook
-            buildPackages.pkg-config
-
-            # Tests
-            buildPackages.git
-            buildPackages.mercurial # FIXME: remove? only needed for tests
-            buildPackages.jq # Also for custom mdBook preprocessor.
-            buildPackages.openssh # only needed for tests (ssh-keygen)
-          ]
-          ++ lib.optionals stdenv.hostPlatform.isLinux [(buildPackages.util-linuxMinimal or buildPackages.utillinuxMinimal)]
-          # Official releases don't have rl-next, so we don't need to compile a changelog
-          ++ lib.optional (!officialRelease && buildUnreleasedNotes) changelog-d
-          ;
-
-        buildDeps =
-          [ curl
-            bzip2 xz brotli editline
-            openssl sqlite
-            libarchive
-            (pkgs.libgit2.overrideAttrs (attrs: {
+          libgit2-nix = final.libgit2.overrideAttrs (attrs: {
             src = libgit2;
             version = libgit2.lastModifiedDate;
-              cmakeFlags = (attrs.cmakeFlags or []) ++ ["-DUSE_SSH=exec"];
-            }))
-            boost-nix
-            lowdown-nix
-            libsodium
-          ]
-          ++ lib.optionals stdenv.isLinux [libseccomp]
-          ++ lib.optional stdenv.hostPlatform.isx86_64 libcpuid;
-
-        checkDeps = [
-          gtest
-          rapidcheck
-        ];
-
-        internalApiDocsDeps = [
-          buildPackages.doxygen
-        ];
-
-        awsDeps = lib.optional (stdenv.isLinux || stdenv.isDarwin)
-          (aws-sdk-cpp.override {
-            apis = ["s3" "transfer"];
-            customMemoryManagement = false;
+            cmakeFlags = attrs.cmakeFlags or []
+              ++ [ "-DUSE_SSH=exec" ];
           });
 
-        propagatedDeps =
-          [ ((boehmgc.override {
+          boehmgc-nix = (final.boehmgc.override {
             enableLargeConfig = true;
           }).overrideAttrs(o: {
             patches = (o.patches or []) ++ [
               ./boehmgc-coroutine-sp-fallback.diff
+
+              # https://github.com/ivmai/bdwgc/pull/586
+              ./boehmgc-traceable_allocator-public.diff
             ];
-            })
-            )
-            nlohmann_json
-          ];
-      };
-
-      installScriptFor = systems:
-        with nixpkgsFor.x86_64-linux.native;
-        runCommand "installer-script"
-          { buildInputs = [ nix ];
-          }
-          ''
-            mkdir -p $out/nix-support
-
-            # Converts /nix/store/50p3qk8k...-nix-2.4pre20201102_550e11f/bin/nix to 50p3qk8k.../bin/nix.
-            tarballPath() {
-              # Remove the store prefix
-              local path=''${1#${builtins.storeDir}/}
-              # Get the path relative to the derivation root
-              local rest=''${path#*/}
-              # Get the derivation hash
-              local drvHash=''${path%%-*}
-              echo "$drvHash/$rest"
-            }
-
-            substitute ${./scripts/install.in} $out/install \
-              ${pkgs.lib.concatMapStrings
-                (system: let
-                    tarball = if builtins.elem system crossSystems then self.hydraJobs.binaryTarballCross.x86_64-linux.${system} else self.hydraJobs.binaryTarball.${system};
-                  in '' \
-                  --replace '@tarballHash_${system}@' $(nix --experimental-features nix-command hash-file --base16 --type sha256 ${tarball}/*.tar.xz) \
-                  --replace '@tarballPath_${system}@' $(tarballPath ${tarball}/*.tar.xz) \
-                  ''
-                )
-                systems
-              } --replace '@nixVersion@' ${version}
-
-            echo "file installer $out/install" >> $out/nix-support/hydra-build-products
-          '';
-
-      testNixVersions = pkgs: client: daemon: with commonDeps { inherit pkgs; }; with pkgs.lib; pkgs.stdenv.mkDerivation {
-        NIX_DAEMON_PACKAGE = daemon;
-        NIX_CLIENT_PACKAGE = client;
-        name =
-          "nix-tests"
-          + optionalString
-            (versionAtLeast daemon.version "2.4pre20211005" &&
-             versionAtLeast client.version "2.4pre20211005")
-            "-${client.version}-against-${daemon.version}";
-        inherit version;
-
-        src = fileset.toSource {
-          root = ./.;
-          fileset = fileset.intersect baseFiles (fileset.unions [
-            configureFiles
-            topLevelBuildFiles
-            functionalTestFiles
-          ]);
-        };
-
-        VERSION_SUFFIX = versionSuffix;
-
-        nativeBuildInputs = nativeBuildDeps;
-        buildInputs = buildDeps ++ awsDeps ++ checkDeps;
-        propagatedBuildInputs = propagatedDeps;
-
-        enableParallelBuilding = true;
-
-        configureFlags =
-          testConfigureFlags # otherwise configure fails
-          ++ [ "--disable-build" ];
-        dontBuild = true;
-        doInstallCheck = true;
-
-        installPhase = ''
-          mkdir -p $out
-        '';
-
-        installCheckPhase = ''
-          mkdir -p src/nix-channel
-          make installcheck -j$NIX_BUILD_CORES -l$NIX_BUILD_CORES
-        '';
-      };
-
-      binaryTarball = nix: pkgs:
-        let
-          inherit (pkgs) buildPackages;
-          inherit (pkgs) cacert;
-          installerClosureInfo = buildPackages.closureInfo { rootPaths = [ nix cacert ]; };
-        in
-
-        buildPackages.runCommand "nix-binary-tarball-${version}"
-          { #nativeBuildInputs = lib.optional (system != "aarch64-linux") shellcheck;
-            meta.description = "Distribution-independent Nix bootstrap binaries for ${pkgs.system}";
-          }
-          ''
-            cp ${installerClosureInfo}/registration $TMPDIR/reginfo
-            cp ${./scripts/create-darwin-volume.sh} $TMPDIR/create-darwin-volume.sh
-            substitute ${./scripts/install-nix-from-closure.sh} $TMPDIR/install \
-              --subst-var-by nix ${nix} \
-              --subst-var-by cacert ${cacert}
-
-            substitute ${./scripts/install-darwin-multi-user.sh} $TMPDIR/install-darwin-multi-user.sh \
-              --subst-var-by nix ${nix} \
-              --subst-var-by cacert ${cacert}
-            substitute ${./scripts/install-systemd-multi-user.sh} $TMPDIR/install-systemd-multi-user.sh \
-              --subst-var-by nix ${nix} \
-              --subst-var-by cacert ${cacert}
-            substitute ${./scripts/install-multi-user.sh} $TMPDIR/install-multi-user \
-              --subst-var-by nix ${nix} \
-              --subst-var-by cacert ${cacert}
-
-            if type -p shellcheck; then
-              # SC1090: Don't worry about not being able to find
-              #         $nix/etc/profile.d/nix.sh
-              shellcheck --exclude SC1090 $TMPDIR/install
-              shellcheck $TMPDIR/create-darwin-volume.sh
-              shellcheck $TMPDIR/install-darwin-multi-user.sh
-              shellcheck $TMPDIR/install-systemd-multi-user.sh
-
-              # SC1091: Don't panic about not being able to source
-              #         /etc/profile
-              # SC2002: Ignore "useless cat" "error", when loading
-              #         .reginfo, as the cat is a much cleaner
-              #         implementation, even though it is "useless"
-              # SC2116: Allow ROOT_HOME=$(echo ~root) for resolving
-              #         root's home directory
-              shellcheck --external-sources \
-                --exclude SC1091,SC2002,SC2116 $TMPDIR/install-multi-user
-            fi
-
-            chmod +x $TMPDIR/install
-            chmod +x $TMPDIR/create-darwin-volume.sh
-            chmod +x $TMPDIR/install-darwin-multi-user.sh
-            chmod +x $TMPDIR/install-systemd-multi-user.sh
-            chmod +x $TMPDIR/install-multi-user
-            dir=nix-${version}-${pkgs.system}
-            fn=$out/$dir.tar.xz
-            mkdir -p $out/nix-support
-            echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
-            tar cvfJ $fn \
-              --owner=0 --group=0 --mode=u+rw,uga+r \
-              --mtime='1970-01-01' \
-              --absolute-names \
-              --hard-dereference \
-              --transform "s,$TMPDIR/install,$dir/install," \
-              --transform "s,$TMPDIR/create-darwin-volume.sh,$dir/create-darwin-volume.sh," \
-              --transform "s,$TMPDIR/reginfo,$dir/.reginfo," \
-              --transform "s,$NIX_STORE,$dir/store,S" \
-              $TMPDIR/install \
-              $TMPDIR/create-darwin-volume.sh \
-              $TMPDIR/install-darwin-multi-user.sh \
-              $TMPDIR/install-systemd-multi-user.sh \
-              $TMPDIR/install-multi-user \
-              $TMPDIR/reginfo \
-              $(cat ${installerClosureInfo}/store-paths)
-          '';
-
-      overlayFor = getStdenv: final: prev:
-        let currentStdenv = getStdenv final; in
-        {
-          nixStable = prev.nix;
-
-          # Forward from the previous stage as we don’t want it to pick the lowdown override
-          nixUnstable = prev.nixUnstable;
-
-          nix =
-          with final;
-          with commonDeps {
-            inherit pkgs;
-            inherit (currentStdenv.hostPlatform) isStatic;
-          };
-          let
-            canRunInstalled = currentStdenv.buildPlatform.canExecute currentStdenv.hostPlatform;
-          in currentStdenv.mkDerivation (finalAttrs: {
-            name = "nix-${version}";
-            inherit version;
-
-            src = nixSrc;
-            VERSION_SUFFIX = versionSuffix;
-
-            outputs = [ "out" "dev" "doc" ]
-              ++ lib.optional (currentStdenv.hostPlatform != currentStdenv.buildPlatform) "check";
-
-            nativeBuildInputs = nativeBuildDeps;
-            buildInputs = buildDeps
-              # There have been issues building these dependencies
-              ++ lib.optionals (currentStdenv.hostPlatform == currentStdenv.buildPlatform) awsDeps
-              ++ lib.optionals finalAttrs.doCheck checkDeps;
-
-            propagatedBuildInputs = propagatedDeps;
-
-            disallowedReferences = [ boost-nix ];
-
-            preConfigure = lib.optionalString (! currentStdenv.hostPlatform.isStatic)
-              ''
-                # Copy libboost_context so we don't get all of Boost in our closure.
-                # https://github.com/NixOS/nixpkgs/issues/45462
-                mkdir -p $out/lib
-                cp -pd ${boost-nix}/lib/{libboost_context*,libboost_thread*,libboost_system*,libboost_regex*} $out/lib
-                rm -f $out/lib/*.a
-                ${lib.optionalString currentStdenv.hostPlatform.isLinux ''
-                  chmod u+w $out/lib/*.so.*
-                  patchelf --set-rpath $out/lib:${currentStdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
-                ''}
-                ${lib.optionalString currentStdenv.hostPlatform.isDarwin ''
-                  for LIB in $out/lib/*.dylib; do
-                    chmod u+w $LIB
-                    install_name_tool -id $LIB $LIB
-                    install_name_tool -delete_rpath ${boost-nix}/lib/ $LIB || true
-                  done
-                  install_name_tool -change ${boost-nix}/lib/libboost_system.dylib $out/lib/libboost_system.dylib $out/lib/libboost_thread.dylib
-                ''}
-              '';
-
-            configureFlags = configureFlags ++
-              [ "--sysconfdir=/etc" ] ++
-              lib.optional stdenv.hostPlatform.isStatic "--enable-embedded-sandbox-shell" ++
-              [ (lib.enableFeature finalAttrs.doCheck "tests") ] ++
-              lib.optionals finalAttrs.doCheck testConfigureFlags ++
-              lib.optional (!canRunInstalled) "--disable-doc-gen";
-
-            enableParallelBuilding = true;
-
-            makeFlags = "profiledir=$(out)/etc/profile.d PRECOMPILE_HEADERS=1";
-
-            doCheck = true;
-
-            installFlags = "sysconfdir=$(out)/etc";
-
-            postInstall = ''
-              mkdir -p $doc/nix-support
-              echo "doc manual $doc/share/doc/nix/manual" >> $doc/nix-support/hydra-build-products
-              ${lib.optionalString currentStdenv.hostPlatform.isStatic ''
-              mkdir -p $out/nix-support
-              echo "file binary-dist $out/bin/nix" >> $out/nix-support/hydra-build-products
-              ''}
-              ${lib.optionalString currentStdenv.isDarwin ''
-              install_name_tool \
-                -change ${boost-nix}/lib/libboost_context.dylib \
-                $out/lib/libboost_context.dylib \
-                $out/lib/libnixutil.dylib
-              install_name_tool \
-                -change ${boost-nix}/lib/libboost_regex.dylib \
-                $out/lib/libboost_regex.dylib \
-                $out/lib/libnixexpr.dylib
-              ''}
-            '';
-
-            doInstallCheck = finalAttrs.doCheck;
-            installCheckFlags = "sysconfdir=$(out)/etc";
-            installCheckTarget = "installcheck"; # work around buggy detection in stdenv
-
-            separateDebugInfo = !currentStdenv.hostPlatform.isStatic;
-
-            strictDeps = true;
-
-            hardeningDisable = lib.optional stdenv.hostPlatform.isStatic "pie";
-
-            passthru.perl-bindings = final.callPackage ./perl {
-              inherit fileset;
-              stdenv = currentStdenv;
-            };
-
-            meta.platforms = lib.platforms.unix;
-            meta.mainProgram = "nix";
           });
 
-          boost-nix = final.boost.override {
-            enableIcu = false;
+          changelog-d-nix = final.buildPackages.callPackage ./misc/changelog-d.nix { };
+
+          nix =
+            let
+              officialRelease = false;
+              versionSuffix =
+                if officialRelease
+                then ""
+                else "pre${builtins.substring 0 8 (self.lastModifiedDate or self.lastModified or "19700101")}_${self.shortRev or "dirty"}";
+
+            in final.callPackage ./package.nix {
+              inherit
+                fileset
+                stdenv
+                versionSuffix
+                ;
+              officialRelease = false;
+              boehmgc = final.boehmgc-nix;
+              libgit2 = final.libgit2-nix;
+              busybox-sandbox-shell = final.busybox-sandbox-shell or final.default-busybox-sandbox-shell;
+              changelog-d = final.changelog-d-nix;
+            } // {
+              # this is a proper separate downstream package, but put
+              # here also for back compat reasons.
+              perl-bindings = final.nix-perl-bindings;
             };
 
-          lowdown-nix = with final; currentStdenv.mkDerivation rec {
-            name = "lowdown-0.9.0";
-
-            src = lowdown-src;
-
-            outputs = [ "out" "bin" "dev" ];
-
-            nativeBuildInputs = [ buildPackages.which ];
-
-            configurePhase = ''
-                ${if (currentStdenv.isDarwin && currentStdenv.isAarch64) then "echo \"HAVE_SANDBOX_INIT=false\" > configure.local" else ""}
-                ./configure \
-                  PREFIX=${placeholder "dev"} \
-                  BINDIR=${placeholder "bin"}/bin
-            '';
+            nix-perl-bindings = final.callPackage ./perl {
+              inherit fileset stdenv;
             };
+
           };
 
     in {
@@ -539,6 +224,8 @@
         # Binary package for various platforms.
         build = forAllSystems (system: self.packages.${system}.nix);
 
+        shellInputs = forAllSystems (system: self.devShells.${system}.default.inputDerivation);
+
         buildStatic = lib.genAttrs linux64BitSystems (system: self.packages.${system}.nix-static);
 
         buildCross = forAllCrossSystems (crossSystem:
@@ -572,66 +259,40 @@
         # to https://nixos.org/nix/install. It downloads the binary
         # tarball for the user's system and calls the second half of the
         # installation script.
-        installerScript = installScriptFor [ "x86_64-linux" "i686-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" "armv6l-linux" "armv7l-linux" ];
-        installerScriptForGHA = installScriptFor [ "x86_64-linux" "x86_64-darwin" "armv6l-linux" "armv7l-linux"];
+        installerScript = installScriptFor [
+          # Native
+          self.hydraJobs.binaryTarball."x86_64-linux"
+          self.hydraJobs.binaryTarball."i686-linux"
+          self.hydraJobs.binaryTarball."aarch64-linux"
+          self.hydraJobs.binaryTarball."x86_64-darwin"
+          self.hydraJobs.binaryTarball."aarch64-darwin"
+          # Cross
+          self.hydraJobs.binaryTarballCross."x86_64-linux"."armv6l-unknown-linux-gnueabihf"
+          self.hydraJobs.binaryTarballCross."x86_64-linux"."armv7l-unknown-linux-gnueabihf"
+        ];
+        installerScriptForGHA = installScriptFor [
+          # Native
+          self.hydraJobs.binaryTarball."x86_64-linux"
+          self.hydraJobs.binaryTarball."x86_64-darwin"
+          # Cross
+          self.hydraJobs.binaryTarballCross."x86_64-linux"."armv6l-unknown-linux-gnueabihf"
+          self.hydraJobs.binaryTarballCross."x86_64-linux"."armv7l-unknown-linux-gnueabihf"
+        ];
 
         # docker image with Nix inside
         dockerImage = lib.genAttrs linux64BitSystems (system: self.packages.${system}.dockerImage);
 
         # Line coverage analysis.
-        coverage =
-          with nixpkgsFor.x86_64-linux.native;
-          with commonDeps { inherit pkgs; };
-
-          releaseTools.coverageAnalysis {
-            name = "nix-coverage-${version}";
-
-            src = nixSrc;
-
-            configureFlags = testConfigureFlags;
-
-            enableParallelBuilding = true;
-
-            nativeBuildInputs = nativeBuildDeps;
-            buildInputs = buildDeps ++ propagatedDeps ++ awsDeps ++ checkDeps;
-
-            dontInstall = false;
-
-            doInstallCheck = true;
-            installCheckTarget = "installcheck"; # work around buggy detection in stdenv
-
-            lcovFilter = [ "*/boost/*" "*-tab.*" ];
-
-            hardeningDisable = ["fortify"];
-
-            NIX_CFLAGS_COMPILE = "-DCOVERAGE=1";
+        coverage = nixpkgsFor.x86_64-linux.native.nix.override {
+          pname = "nix-coverage";
+          withCoverageChecks = true;
         };
 
         # API docs for Nix's unstable internal C++ interfaces.
-        internal-api-docs =
-          with nixpkgsFor.x86_64-linux.native;
-          with commonDeps { inherit pkgs; };
-
-          stdenv.mkDerivation {
-            pname = "nix-internal-api-docs";
-            inherit version;
-
-            src = nixSrc;
-
-            configureFlags = testConfigureFlags ++ internalApiDocsConfigureFlags;
-
-            nativeBuildInputs = nativeBuildDeps;
-            buildInputs = buildDeps ++ propagatedDeps
-              ++ awsDeps ++ checkDeps ++ internalApiDocsDeps;
-
-            dontBuild = true;
-
-            installTargets = [ "internal-api-html" ];
-
-            postInstall = ''
-              mkdir -p $out/nix-support
-              echo "doc internal-api-docs $out/share/doc/nix/internal-api/html" >> $out/nix-support/hydra-build-products
-            '';
+        internal-api-docs = nixpkgsFor.x86_64-linux.native.callPackage ./package.nix {
+          inherit fileset;
+          doBuild = false;
+          enableInternalAPIDocs = true;
         };
 
         # System tests.
@@ -640,7 +301,9 @@
           # Make sure that nix-env still produces the exact same result
           # on a particular version of Nixpkgs.
           evalNixpkgs =
-            with nixpkgsFor.x86_64-linux.native;
+            let
+              inherit (nixpkgsFor.x86_64-linux.native) runCommand nix;
+            in
             runCommand "eval-nixos" { buildInputs = [ nix ]; }
               ''
                 type -p nix-env
@@ -690,6 +353,11 @@
         perlBindings = self.hydraJobs.perlBindings.${system};
         installTests = self.hydraJobs.installTests.${system};
         nixpkgsLibTests = self.hydraJobs.tests.nixpkgsLibTests.${system};
+        rl-next =
+          let pkgs = nixpkgsFor.${system}.native;
+          in pkgs.buildPackages.runCommand "test-rl-next-release-notes" { } ''
+          LANG=C.UTF-8 ${pkgs.changelog-d-nix}/bin/changelog-d ${./doc/manual/rl-next} >$out
+        '';
       } // (lib.optionalAttrs (builtins.elem system linux64BitSystems)) {
         dockerImage = self.hydraJobs.dockerImage.${system};
       });
@@ -727,39 +395,9 @@
           stdenvs)));
 
       devShells = let
-        makeShell = pkgs: stdenv:
-          let
-            canRunInstalled = stdenv.buildPlatform.canExecute stdenv.hostPlatform;
-          in
-          with commonDeps { inherit pkgs; };
-          stdenv.mkDerivation {
-            name = "nix";
-
-            outputs = [ "out" "dev" "doc" ]
-              ++ lib.optional (stdenv.hostPlatform != stdenv.buildPlatform) "check";
-
-            nativeBuildInputs = nativeBuildDeps
-              ++ lib.optional stdenv.cc.isClang pkgs.buildPackages.bear
-              ++ lib.optional
-                (stdenv.cc.isClang && stdenv.hostPlatform == stdenv.buildPlatform)
-                pkgs.buildPackages.clang-tools
-              # We want changelog-d in the shell even if the current build doesn't need it
-              ++ lib.optional (officialRelease || ! buildUnreleasedNotes) changelog-d
-              ;
-
-            buildInputs = buildDeps ++ propagatedDeps
-              ++ awsDeps ++ checkDeps ++ internalApiDocsDeps;
-
-            configureFlags = configureFlags
-              ++ testConfigureFlags ++ internalApiDocsConfigureFlags
-              ++ lib.optional (!canRunInstalled) "--disable-doc-gen";
-
-            enableParallelBuilding = true;
-
+        makeShell = pkgs: stdenv: (pkgs.nix.override { inherit stdenv; }).overrideAttrs (_: {
           installFlags = "sysconfdir=$(out)/etc";
-
-            shellHook =
-              ''
+          shellHook = ''
             PATH=$prefix/bin:$PATH
             unset PYTHONPATH
             export MANPATH=$out/share/man:$MANPATH
@@ -767,7 +405,7 @@
             # Make bash completion work.
             XDG_DATA_DIRS+=:$out/share
           '';
-          };
+        });
         in
         forAllSystems (system:
           let
@@ -778,7 +416,7 @@
           in
             (makeShells "native" nixpkgsFor.${system}.native) //
             (makeShells "static" nixpkgsFor.${system}.static) //
-            (forAllCrossSystems (crossSystem: let pkgs = nixpkgsFor.${system}.cross.${crossSystem}; in makeShell pkgs pkgs.stdenv)) //
+            (lib.genAttrs shellCrossSystems (crossSystem: let pkgs = nixpkgsFor.${system}.cross.${crossSystem}; in makeShell pkgs pkgs.stdenv)) //
             {
               default = self.devShells.${system}.native-stdenvPackages;
             }

maintainers/upload-release.pl

@@ -154,8 +154,8 @@ downloadFile("binaryTarball.x86_64-linux", "1");
 downloadFile("binaryTarball.aarch64-linux", "1");
 downloadFile("binaryTarball.x86_64-darwin", "1");
 downloadFile("binaryTarball.aarch64-darwin", "1");
-downloadFile("binaryTarballCross.x86_64-linux.armv6l-linux", "1");
-downloadFile("binaryTarballCross.x86_64-linux.armv7l-linux", "1");
+downloadFile("binaryTarballCross.x86_64-linux.armv6l-unknown-linux-gnueabihf", "1");
+downloadFile("binaryTarballCross.x86_64-linux.armv7l-unknown-linux-gnueabihf", "1");
 downloadFile("installerScript", "1");
 
 # Upload docker images to dockerhub.

misc/changelog-d.cabal.nix

@@ -0,0 +1,31 @@
+{ mkDerivation, aeson, base, bytestring, cabal-install-parsers
+, Cabal-syntax, containers, directory, filepath, frontmatter
+, generic-lens-lite, lib, mtl, optparse-applicative, parsec, pretty
+, regex-applicative, text, pkgs
+}:
+let rev = "f30f6969e9cd8b56242309639d58acea21c99d06";
+in
+mkDerivation {
+  pname = "changelog-d";
+  version = "0.1";
+  src = pkgs.fetchurl {
+    name = "changelog-d-${rev}.tar.gz";
+    url = "https://codeberg.org/roberth/changelog-d/archive/${rev}.tar.gz";
+    hash = "sha256-8a2+i5u7YoszAgd5OIEW0eYUcP8yfhtoOIhLJkylYJ4=";
+  } // { inherit rev; };
+  isLibrary = false;
+  isExecutable = true;
+  libraryHaskellDepends = [
+    aeson base bytestring cabal-install-parsers Cabal-syntax containers
+    directory filepath frontmatter generic-lens-lite mtl parsec pretty
+    regex-applicative text
+  ];
+  executableHaskellDepends = [
+    base bytestring Cabal-syntax directory filepath
+    optparse-applicative
+  ];
+  doHaddock = false;
+  description = "Concatenate changelog entries into a single one";
+  license = lib.licenses.gpl3Plus;
+  mainProgram = "changelog-d";
+}

misc/changelog-d.nix

@@ -0,0 +1,31 @@
+# Taken temporarily from <nixpkgs/pkgs/by-name/ch/changelog-d/package.nix>
+{
+  callPackage,
+  lib,
+  haskell,
+  haskellPackages,
+}:
+
+let
+  hsPkg = haskellPackages.callPackage ./changelog-d.cabal.nix { };
+
+  addCompletions = haskellPackages.generateOptparseApplicativeCompletions ["changelog-d"];
+
+  haskellModifications =
+    lib.flip lib.pipe [
+      addCompletions
+      haskell.lib.justStaticExecutables
+    ];
+
+  mkDerivationOverrides = finalAttrs: oldAttrs: {
+
+    version = oldAttrs.version + "-git-${lib.strings.substring 0 7 oldAttrs.src.rev}";
+
+    meta = oldAttrs.meta // {
+      homepage = "https://codeberg.org/roberth/changelog-d";
+      maintainers = [ lib.maintainers.roberth ];
+    };
+
+  };
+in
+  (haskellModifications hsPkg).overrideAttrs mkDerivationOverrides

mk/build-dir.mk

@@ -0,0 +1,10 @@
+# Initialise support for build directories.
+builddir ?=
+
+ifdef builddir
+  buildprefix = $(builddir)/
+  buildprefixrel = $(builddir)
+else
+  buildprefix =
+  buildprefixrel = .
+endif

mk/common-test.sh

@@ -1,7 +1,7 @@
 # Remove overall test dir (at most one of the two should match) and
 # remove file extension.
 test_name=$(echo -n "$test" | sed \
-    -e "s|^unit-test-data/||" \
+    -e "s|^tests/unit/[^/]*/data/||" \
     -e "s|^tests/functional/||" \
     -e "s|\.sh$||" \
     )

mk/install-dirs.mk

@@ -0,0 +1,11 @@
+# Default installation paths.
+prefix ?= /usr/local
+libdir ?= $(prefix)/lib
+bindir ?= $(prefix)/bin
+libexecdir ?= $(prefix)/libexec
+datadir ?= $(prefix)/share
+localstatedir ?= $(prefix)/var
+sysconfdir ?= $(prefix)/etc
+mandir ?= $(prefix)/share/man
+
+DESTDIR ?=

mk/lib.mk

@@ -43,27 +43,6 @@ define newline
 endef
 
 
-# Default installation paths.
-prefix ?= /usr/local
-libdir ?= $(prefix)/lib
-bindir ?= $(prefix)/bin
-libexecdir ?= $(prefix)/libexec
-datadir ?= $(prefix)/share
-localstatedir ?= $(prefix)/var
-sysconfdir ?= $(prefix)/etc
-mandir ?= $(prefix)/share/man
-
-
-# Initialise support for build directories.
-builddir ?=
-
-ifdef builddir
-  buildprefix = $(builddir)/
-else
-  buildprefix =
-endif
-
-
 # Pass -fPIC if we're building dynamic libraries.
 BUILD_SHARED_LIBS ?= 1
 
@@ -94,6 +73,8 @@ ifeq ($(BUILD_DEBUG), 1)
 endif
 
 
+include mk/build-dir.mk
+include mk/install-dirs.mk
 include mk/functions.mk
 include mk/tracing.mk
 include mk/clean.mk

mk/programs.mk

@@ -87,6 +87,6 @@ define build-program
   # Phony target to run this program (typically as a dependency of 'check').
   .PHONY: $(1)_RUN
   $(1)_RUN: $$($(1)_PATH)
-	$(trace-test) $$(UNIT_TEST_ENV) $$($(1)_PATH)
+	$(trace-test) $$($(1)_ENV) $$($(1)_PATH)
 
 endef

mk/templates.mk

@@ -10,10 +10,10 @@ endef
 
 ifneq ($(MAKECMDGOALS), clean)
 
-%.h: %.h.in
-	$(trace-gen) rm -f $@ && ./config.status --quiet --header=$@
+$(buildprefix)%.h: %.h.in
+	$(trace-gen) rm -f $@ && cd $(buildprefixrel) && ./config.status --quiet --header=$(@:$(buildprefix)%=%)
 
-%: %.in
-	$(trace-gen) rm -f $@ && ./config.status --quiet --file=$@
+$(buildprefix)%: %.in
+	$(trace-gen) rm -f $@ && cd $(buildprefixrel) && ./config.status --quiet --file=$(@:$(buildprefix)%=%)
 
 endif

package.nix

@@ -0,0 +1,385 @@
+{ lib
+, stdenv
+, releaseTools
+, autoconf-archive
+, autoreconfHook
+, aws-sdk-cpp
+, boehmgc
+, nlohmann_json
+, bison
+, boost
+, brotli
+, bzip2
+, changelog-d
+, curl
+, editline
+, fileset
+, flex
+, git
+, gtest
+, jq
+, doxygen
+, libarchive
+, libcpuid
+, libgit2
+, libseccomp
+, libsodium
+, lowdown
+, mdbook
+, mdbook-linkcheck
+, mercurial
+, openssh
+, openssl
+, pkg-config
+, rapidcheck
+, sqlite
+, util-linux
+, xz
+
+, busybox-sandbox-shell ? null
+
+# Configuration Options
+#:
+# This probably seems like too many degrees of freedom, but it
+# faithfully reflects how the underlying configure + make build system
+# work. The top-level flake.nix will choose useful combinations of these
+# options to CI.
+
+, pname ? "nix"
+
+, versionSuffix ? ""
+, officialRelease ? false
+
+# Whether to build Nix. Useful to skip for tasks like (a) just
+# generating API docs or (b) testing existing pre-built versions of Nix
+, doBuild ? true
+
+# Run the unit tests as part of the build. See `installUnitTests` for an
+# alternative to this.
+, doCheck ? __forDefaults.canRunInstalled
+
+# Run the functional tests as part of the build.
+, doInstallCheck ? test-client != null || __forDefaults.canRunInstalled
+
+# Check test coverage of Nix. Probably want to use with with at least
+# one of `doCHeck` or `doInstallCheck` enabled.
+, withCoverageChecks ? false
+
+# Whether to build the regular manual
+, enableManual ? __forDefaults.canRunInstalled
+
+# Whether to compile `rl-next.md`, the release notes for the next
+# not-yet-released version of Nix in the manul, from the individual
+# change log entries in the directory.
+, buildUnreleasedNotes ? false
+
+# Whether to build the internal API docs, can be done separately from
+# everything else.
+, enableInternalAPIDocs ? false
+
+# Whether to install unit tests. This is useful when cross compiling
+# since we cannot run them natively during the build, but can do so
+# later.
+, installUnitTests ? __forDefaults.canRunInstalled
+
+# For running the functional tests against a pre-built Nix. Probably
+# want to use in conjunction with `doBuild = false;`.
+, test-daemon ? null
+, test-client ? null
+
+# Not a real argument, just the only way to approximate let-binding some
+# stuff for argument defaults.
+, __forDefaults ? {
+    canRunInstalled = doBuild && stdenv.buildPlatform.canExecute stdenv.hostPlatform;
+  }
+}:
+
+let
+  version = lib.fileContents ./.version + versionSuffix;
+
+  # selected attributes with defaults, will be used to define some
+  # things which should instead be gotten via `finalAttrs` in order to
+  # work with overriding.
+  attrs = {
+    inherit doBuild doCheck doInstallCheck;
+  };
+
+  filesets = {
+    baseFiles = fileset.fileFilter (f: f.name != ".gitignore") ./.;
+
+    configureFiles = fileset.unions [
+      ./.version
+      ./configure.ac
+      ./m4
+      # TODO: do we really need README.md? It doesn't seem used in the build.
+      ./README.md
+    ];
+
+    topLevelBuildFiles = fileset.unions [
+      ./local.mk
+      ./Makefile
+      ./Makefile.config.in
+      ./mk
+    ];
+
+    functionalTestFiles = fileset.unions [
+      ./tests/functional
+      (fileset.fileFilter (f: lib.strings.hasPrefix "nix-profile" f.name) ./scripts)
+    ];
+  };
+
+  mkDerivation =
+    if withCoverageChecks
+    then
+      # TODO support `finalAttrs` args function in
+      # `releaseTools.coverageAnalysis`.
+      argsFun:
+         releaseTools.coverageAnalysis (let args = argsFun args; in args)
+    else stdenv.mkDerivation;
+in
+
+mkDerivation (finalAttrs: let
+
+  inherit (finalAttrs)
+    doCheck
+    doInstallCheck
+    ;
+
+  doBuild = !finalAttrs.dontBuild;
+
+  # Either running the unit tests during the build, or installing them
+  # to be run later, requiresthe unit tests to be built.
+  buildUnitTests = doCheck || installUnitTests;
+
+  anySortOfTesting = buildUnitTests || doInstallCheck;
+
+in {
+  inherit pname version;
+
+  src =
+    let
+
+    in
+      fileset.toSource {
+        root = ./.;
+        fileset = fileset.intersect filesets.baseFiles (fileset.unions ([
+          filesets.configureFiles
+          filesets.topLevelBuildFiles
+          ./doc/internal-api
+        ] ++ lib.optionals doBuild [
+          ./boehmgc-coroutine-sp-fallback.diff
+          ./doc
+          ./misc
+          ./precompiled-headers.h
+          ./src
+          ./tests/unit
+          ./COPYING
+          ./scripts/local.mk
+        ] ++ lib.optionals anySortOfTesting [
+          filesets.functionalTestFiles
+        ]));
+      };
+
+  VERSION_SUFFIX = versionSuffix;
+
+  outputs = [ "out" ]
+    ++ lib.optional doBuild "dev"
+    # If we are doing just build or just docs, the one thing will use
+    # "out". We only need additional outputs if we are doing both.
+    ++ lib.optional (doBuild && (enableManual || enableInternalAPIDocs)) "doc"
+    ++ lib.optional installUnitTests "check";
+
+  nativeBuildInputs = [
+    autoconf-archive
+    autoreconfHook
+    pkg-config
+  ] ++ lib.optionals doBuild [
+    bison
+    flex
+  ] ++ lib.optionals enableManual [
+    (lib.getBin lowdown)
+    mdbook
+    mdbook-linkcheck
+  ] ++ lib.optionals (doInstallCheck || enableManual) [
+    jq # Also for custom mdBook preprocessor.
+  ] ++ lib.optional stdenv.hostPlatform.isLinux util-linux
+    # Official releases don't have rl-next, so we don't need to compile a
+    # changelog
+    ++ lib.optional (!officialRelease && buildUnreleasedNotes) changelog-d
+    ++ lib.optional enableInternalAPIDocs doxygen
+  ;
+
+  buildInputs = lib.optionals doBuild [
+    boost
+    brotli
+    bzip2
+    curl
+    libarchive
+    libgit2
+    libsodium
+    openssl
+    sqlite
+    xz
+  ] ++ lib.optionals (!stdenv.hostPlatform.isWindows) [
+    editline
+    lowdown
+  ] ++ lib.optional stdenv.isLinux libseccomp
+    ++ lib.optional stdenv.hostPlatform.isx86_64 libcpuid
+    # There have been issues building these dependencies
+    ++ lib.optional (stdenv.hostPlatform == stdenv.buildPlatform && (stdenv.isLinux || stdenv.isDarwin))
+      (aws-sdk-cpp.override {
+        apis = ["s3" "transfer"];
+        customMemoryManagement = false;
+      })
+  ;
+
+  propagatedBuildInputs = [
+    boehmgc
+    nlohmann_json
+  ];
+
+  dontBuild = !attrs.doBuild;
+  doCheck = attrs.doCheck;
+
+  checkInputs = [
+    gtest
+    rapidcheck
+  ];
+
+  nativeCheckInputs = [
+    git
+    mercurial
+    openssh
+  ];
+
+  disallowedReferences = [ boost ];
+
+  preConfigure = lib.optionalString (doBuild && ! stdenv.hostPlatform.isStatic) (
+    ''
+      # Copy libboost_context so we don't get all of Boost in our closure.
+      # https://github.com/NixOS/nixpkgs/issues/45462
+      mkdir -p $out/lib
+      cp -pd ${boost}/lib/{libboost_context*,libboost_thread*,libboost_system*,libboost_regex*} $out/lib
+      rm -f $out/lib/*.a
+    '' + lib.optionalString stdenv.hostPlatform.isLinux ''
+      chmod u+w $out/lib/*.so.*
+      patchelf --set-rpath $out/lib:${stdenv.cc.cc.lib}/lib $out/lib/libboost_thread.so.*
+    '' + lib.optionalString stdenv.hostPlatform.isDarwin ''
+      for LIB in $out/lib/*.dylib; do
+        chmod u+w $LIB
+        install_name_tool -id $LIB $LIB
+        install_name_tool -delete_rpath ${boost}/lib/ $LIB || true
+      done
+      install_name_tool -change ${boost}/lib/libboost_system.dylib $out/lib/libboost_system.dylib $out/lib/libboost_thread.dylib
+    ''
+  );
+
+  configureFlags = [
+    "--sysconfdir=/etc"
+    (lib.enableFeature doBuild "build")
+    (lib.enableFeature anySortOfTesting "tests")
+    (lib.enableFeature enableInternalAPIDocs "internal-api-docs")
+    (lib.enableFeature enableManual "doc-gen")
+    (lib.enableFeature installUnitTests "install-unit-tests")
+  ] ++ lib.optionals installUnitTests [
+    "--with-check-bin-dir=${builtins.placeholder "check"}/bin"
+    "--with-check-lib-dir=${builtins.placeholder "check"}/lib"
+  ] ++ lib.optionals (doBuild) [
+    "--with-boost=${boost}/lib"
+  ] ++ lib.optionals (doBuild && stdenv.isLinux) [
+    "--with-sandbox-shell=${busybox-sandbox-shell}/bin/busybox"
+  ] ++ lib.optional (doBuild && stdenv.isLinux && !(stdenv.hostPlatform.isStatic && stdenv.system == "aarch64-linux"))
+       "LDFLAGS=-fuse-ld=gold"
+    ++ lib.optional (doBuild && stdenv.hostPlatform.isStatic) "--enable-embedded-sandbox-shell"
+    ++ lib.optional buildUnitTests "RAPIDCHECK_HEADERS=${lib.getDev rapidcheck}/extras/gtest/include";
+
+  enableParallelBuilding = true;
+
+  makeFlags = "profiledir=$(out)/etc/profile.d PRECOMPILE_HEADERS=1";
+
+  installTargets = lib.optional doBuild "install"
+    ++ lib.optional enableInternalAPIDocs "internal-api-html";
+
+  installFlags = "sysconfdir=$(out)/etc";
+
+  # In this case we are probably just running tests, and so there isn't
+  # anything to install, we just make an empty directory to signify tests
+  # succeeded.
+  installPhase = if finalAttrs.installTargets != [] then null else ''
+    mkdir -p $out
+  '';
+
+  postInstall = lib.optionalString doBuild (
+    ''
+      mkdir -p $doc/nix-support
+      echo "doc manual $doc/share/doc/nix/manual" >> $doc/nix-support/hydra-build-products
+    '' + lib.optionalString stdenv.hostPlatform.isStatic ''
+      mkdir -p $out/nix-support
+      echo "file binary-dist $out/bin/nix" >> $out/nix-support/hydra-build-products
+    '' + lib.optionalString stdenv.isDarwin ''
+      install_name_tool \
+      -change ${boost}/lib/libboost_context.dylib \
+      $out/lib/libboost_context.dylib \
+      $out/lib/libnixutil.dylib
+    ''
+  ) + lib.optionalString enableInternalAPIDocs ''
+    mkdir -p ''${!outputDoc}/nix-support
+    echo "doc internal-api-docs $out/share/doc/nix/internal-api/html" >> ''${!outputDoc}/nix-support/hydra-build-products
+  '';
+
+  doInstallCheck = attrs.doInstallCheck;
+
+  installCheckFlags = "sysconfdir=$(out)/etc";
+  # Work around buggy detection in stdenv.
+  installCheckTarget = "installcheck";
+
+  # Work around weird bug where it doesn't think there is a Makefile.
+  installCheckPhase = if (!doBuild && doInstallCheck) then ''
+    mkdir -p src/nix-channel
+    make installcheck -j$NIX_BUILD_CORES -l$NIX_BUILD_CORES
+  '' else null;
+
+  # Needed for tests if we are not doing a build, but testing existing
+  # built Nix.
+  preInstallCheck = lib.optionalString (! doBuild) ''
+    mkdir -p src/nix-channel
+  '';
+
+  separateDebugInfo = !stdenv.hostPlatform.isStatic;
+
+  # TODO `releaseTools.coverageAnalysis` in Nixpkgs needs to be updated
+  # to work with `strictDeps`.
+  strictDeps = !withCoverageChecks;
+
+  hardeningDisable = lib.optional stdenv.hostPlatform.isStatic "pie";
+
+  meta = {
+    platforms = lib.platforms.unix ++ lib.platforms.windows;
+    mainProgram = "nix";
+    broken = !(lib.all (a: a) [
+      # We cannot run or install unit tests if we don't build them or
+      # Nix proper (which they depend on).
+      (installUnitTests -> doBuild)
+      (doCheck -> doBuild)
+      # We have to build the manual to build unreleased notes, as those
+      # are part of the manual
+      (buildUnreleasedNotes -> enableManual)
+      # The build process for the manual currently requires extracting
+      # data from the Nix executable we are trying to document.
+      (enableManual -> doBuild)
+    ]);
+  };
+
+} // lib.optionalAttrs withCoverageChecks {
+  lcovFilter = [ "*/boost/*" "*-tab.*" ];
+
+  hardeningDisable = ["fortify"];
+
+  NIX_CFLAGS_COMPILE = "-DCOVERAGE=1";
+
+  dontInstall = false;
+} // lib.optionalAttrs (test-daemon != null) {
+  NIX_DAEMON_PACKAGE = test-daemon;
+} // lib.optionalAttrs (test-client != null) {
+  NIX_CLIENT_PACKAGE = test-client;
+})

perl/lib/Nix/Store.xs

@@ -9,6 +9,7 @@
 #undef do_close
 
 #include "derivations.hh"
+#include "realisation.hh"
 #include "globals.hh"
 #include "store-api.hh"
 #include "crypto.hh"
@@ -77,7 +78,7 @@ SV * queryReferences(char * path)
 SV * queryPathHash(char * path)
     PPCODE:
         try {
-            auto s = store()->queryPathInfo(store()->parseStorePath(path))->narHash.to_string(HashFormat::Base32, true);
+            auto s = store()->queryPathInfo(store()->parseStorePath(path))->narHash.to_string(HashFormat::Nix32, true);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -103,7 +104,7 @@ SV * queryPathInfo(char * path, int base32)
                 XPUSHs(&PL_sv_undef);
             else
                 XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(*info->deriver).c_str(), 0)));
-            auto s = info->narHash.to_string(base32 ? HashFormat::Base32 : HashFormat::Base16, true);
+            auto s = info->narHash.to_string(base32 ? HashFormat::Nix32 : HashFormat::Base16, true);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
             mXPUSHi(info->registrationTime);
             mXPUSHi(info->narSize);
@@ -204,8 +205,8 @@ void importPaths(int fd, int dontCheckSigs)
 SV * hashPath(char * algo, int base32, char * path)
     PPCODE:
         try {
-            Hash h = hashPath(parseHashType(algo), path).first;
-            auto s = h.to_string(base32 ? HashFormat::Base32 : HashFormat::Base16, false);
+            Hash h = hashPath(parseHashAlgo(algo), path).first;
+            auto s = h.to_string(base32 ? HashFormat::Nix32 : HashFormat::Base16, false);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -215,8 +216,8 @@ SV * hashPath(char * algo, int base32, char * path)
 SV * hashFile(char * algo, int base32, char * path)
     PPCODE:
         try {
-            Hash h = hashFile(parseHashType(algo), path);
-            auto s = h.to_string(base32 ? HashFormat::Base32 : HashFormat::Base16, false);
+            Hash h = hashFile(parseHashAlgo(algo), path);
+            auto s = h.to_string(base32 ? HashFormat::Nix32 : HashFormat::Base16, false);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -226,8 +227,8 @@ SV * hashFile(char * algo, int base32, char * path)
 SV * hashString(char * algo, int base32, char * s)
     PPCODE:
         try {
-            Hash h = hashString(parseHashType(algo), s);
-            auto s = h.to_string(base32 ? HashFormat::Base32 : HashFormat::Base16, false);
+            Hash h = hashString(parseHashAlgo(algo), s);
+            auto s = h.to_string(base32 ? HashFormat::Nix32 : HashFormat::Base16, false);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -237,8 +238,8 @@ SV * hashString(char * algo, int base32, char * s)
 SV * convertHash(char * algo, char * s, int toBase32)
     PPCODE:
         try {
-            auto h = Hash::parseAny(s, parseHashType(algo));
-            auto s = h.to_string(toBase32 ? HashFormat::Base32 : HashFormat::Base16, false);
+            auto h = Hash::parseAny(s, parseHashAlgo(algo));
+            auto s = h.to_string(toBase32 ? HashFormat::Nix32 : HashFormat::Base16, false);
             XPUSHs(sv_2mortal(newSVpv(s.c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -280,7 +281,7 @@ SV * addToStore(char * srcPath, int recursive, char * algo)
     PPCODE:
         try {
             auto method = recursive ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
-            auto path = store()->addToStore(std::string(baseNameOf(srcPath)), srcPath, method, parseHashType(algo));
+            auto path = store()->addToStore(std::string(baseNameOf(srcPath)), srcPath, method, parseHashAlgo(algo));
             XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(path).c_str(), 0)));
         } catch (Error & e) {
             croak("%s", e.what());
@@ -290,7 +291,7 @@ SV * addToStore(char * srcPath, int recursive, char * algo)
 SV * makeFixedOutputPath(int recursive, char * algo, char * hash, char * name)
     PPCODE:
         try {
-            auto h = Hash::parseAny(hash, parseHashType(algo));
+            auto h = Hash::parseAny(hash, parseHashAlgo(algo));
             auto method = recursive ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
             auto path = store()->makeFixedOutputPath(name, FixedOutputInfo {
                 .method = method,

scripts/binary-tarball.nix

@@ -0,0 +1,84 @@
+{ runCommand
+, system
+, buildPackages
+, cacert
+, nix
+}:
+
+let
+
+  installerClosureInfo = buildPackages.closureInfo {
+    rootPaths = [ nix cacert ];
+  };
+
+  inherit (nix) version;
+
+  env = {
+    #nativeBuildInputs = lib.optional (system != "aarch64-linux") shellcheck;
+    meta.description = "Distribution-independent Nix bootstrap binaries for ${system}";
+  };
+
+in
+
+runCommand "nix-binary-tarball-${version}" env ''
+  cp ${installerClosureInfo}/registration $TMPDIR/reginfo
+  cp ${./create-darwin-volume.sh} $TMPDIR/create-darwin-volume.sh
+  substitute ${./install-nix-from-closure.sh} $TMPDIR/install \
+    --subst-var-by nix ${nix} \
+    --subst-var-by cacert ${cacert}
+
+  substitute ${./install-darwin-multi-user.sh} $TMPDIR/install-darwin-multi-user.sh \
+    --subst-var-by nix ${nix} \
+    --subst-var-by cacert ${cacert}
+  substitute ${./install-systemd-multi-user.sh} $TMPDIR/install-systemd-multi-user.sh \
+    --subst-var-by nix ${nix} \
+    --subst-var-by cacert ${cacert}
+  substitute ${./install-multi-user.sh} $TMPDIR/install-multi-user \
+    --subst-var-by nix ${nix} \
+    --subst-var-by cacert ${cacert}
+
+  if type -p shellcheck; then
+    # SC1090: Don't worry about not being able to find
+    #         $nix/etc/profile.d/nix.sh
+    shellcheck --exclude SC1090 $TMPDIR/install
+    shellcheck $TMPDIR/create-darwin-volume.sh
+    shellcheck $TMPDIR/install-darwin-multi-user.sh
+    shellcheck $TMPDIR/install-systemd-multi-user.sh
+
+    # SC1091: Don't panic about not being able to source
+    #         /etc/profile
+    # SC2002: Ignore "useless cat" "error", when loading
+    #         .reginfo, as the cat is a much cleaner
+    #         implementation, even though it is "useless"
+    # SC2116: Allow ROOT_HOME=$(echo ~root) for resolving
+    #         root's home directory
+    shellcheck --external-sources \
+      --exclude SC1091,SC2002,SC2116 $TMPDIR/install-multi-user
+  fi
+
+  chmod +x $TMPDIR/install
+  chmod +x $TMPDIR/create-darwin-volume.sh
+  chmod +x $TMPDIR/install-darwin-multi-user.sh
+  chmod +x $TMPDIR/install-systemd-multi-user.sh
+  chmod +x $TMPDIR/install-multi-user
+  dir=nix-${version}-${system}
+  fn=$out/$dir.tar.xz
+  mkdir -p $out/nix-support
+  echo "file binary-dist $fn" >> $out/nix-support/hydra-build-products
+  tar cvfJ $fn \
+    --owner=0 --group=0 --mode=u+rw,uga+r \
+    --mtime='1970-01-01' \
+    --absolute-names \
+    --hard-dereference \
+    --transform "s,$TMPDIR/install,$dir/install," \
+    --transform "s,$TMPDIR/create-darwin-volume.sh,$dir/create-darwin-volume.sh," \
+    --transform "s,$TMPDIR/reginfo,$dir/.reginfo," \
+    --transform "s,$NIX_STORE,$dir/store,S" \
+    $TMPDIR/install \
+    $TMPDIR/create-darwin-volume.sh \
+    $TMPDIR/install-darwin-multi-user.sh \
+    $TMPDIR/install-systemd-multi-user.sh \
+    $TMPDIR/install-multi-user \
+    $TMPDIR/reginfo \
+    $(cat ${installerClosureInfo}/store-paths)
+''

scripts/installer.nix

@@ -0,0 +1,36 @@
+{ lib
+, runCommand
+, nix
+, tarballs
+}:
+
+runCommand "installer-script" {
+  buildInputs = [ nix ];
+} ''
+  mkdir -p $out/nix-support
+
+  # Converts /nix/store/50p3qk8k...-nix-2.4pre20201102_550e11f/bin/nix to 50p3qk8k.../bin/nix.
+  tarballPath() {
+    # Remove the store prefix
+    local path=''${1#${builtins.storeDir}/}
+    # Get the path relative to the derivation root
+    local rest=''${path#*/}
+    # Get the derivation hash
+    local drvHash=''${path%%-*}
+    echo "$drvHash/$rest"
+  }
+
+  substitute ${./install.in} $out/install \
+    ${lib.concatMapStrings
+      (tarball: let
+          inherit (tarball.stdenv.hostPlatform) system;
+        in '' \
+        --replace '@tarballHash_${system}@' $(nix --experimental-features nix-command hash-file --base16 --type sha256 ${tarball}/*.tar.xz) \
+        --replace '@tarballPath_${system}@' $(tarballPath ${tarball}/*.tar.xz) \
+        ''
+      )
+      tarballs
+    } --replace '@nixVersion@' ${nix.version}
+
+  echo "file installer $out/install" >> $out/nix-support/hydra-build-products
+''

src/libcmd/built-path.cc

@@ -80,7 +80,7 @@ SingleDerivedPath SingleBuiltPath::discardOutputPath() const
     );
 }
 
-nlohmann::json BuiltPath::Built::toJSON(const Store & store) const
+nlohmann::json BuiltPath::Built::toJSON(const StoreDirConfig & store) const
 {
     nlohmann::json res;
     res["drvPath"] = drvPath->toJSON(store);
@@ -90,7 +90,7 @@ nlohmann::json BuiltPath::Built::toJSON(const Store & store) const
     return res;
 }
 
-nlohmann::json SingleBuiltPath::Built::toJSON(const Store & store) const
+nlohmann::json SingleBuiltPath::Built::toJSON(const StoreDirConfig & store) const
 {
     nlohmann::json res;
     res["drvPath"] = drvPath->toJSON(store);
@@ -100,14 +100,14 @@ nlohmann::json SingleBuiltPath::Built::toJSON(const Store & store) const
     return res;
 }
 
-nlohmann::json SingleBuiltPath::toJSON(const Store & store) const
+nlohmann::json SingleBuiltPath::toJSON(const StoreDirConfig & store) const
 {
     return std::visit([&](const auto & buildable) {
         return buildable.toJSON(store);
     }, raw());
 }
 
-nlohmann::json BuiltPath::toJSON(const Store & store) const
+nlohmann::json BuiltPath::toJSON(const StoreDirConfig & store) const
 {
     return std::visit([&](const auto & buildable) {
         return buildable.toJSON(store);

src/libcmd/built-path.hh

@@ -14,9 +14,9 @@ struct SingleBuiltPathBuilt {
 
     SingleDerivedPathBuilt discardOutputPath() const;
 
-    std::string to_string(const Store & store) const;
-    static SingleBuiltPathBuilt parse(const Store & store, std::string_view, std::string_view);
-    nlohmann::json toJSON(const Store & store) const;
+    std::string to_string(const StoreDirConfig & store) const;
+    static SingleBuiltPathBuilt parse(const StoreDirConfig & store, std::string_view, std::string_view);
+    nlohmann::json toJSON(const StoreDirConfig & store) const;
 
     DECLARE_CMP(SingleBuiltPathBuilt);
 };
@@ -41,8 +41,8 @@ struct SingleBuiltPath : _SingleBuiltPathRaw {
 
     SingleDerivedPath discardOutputPath() const;
 
-    static SingleBuiltPath parse(const Store & store, std::string_view);
-    nlohmann::json toJSON(const Store & store) const;
+    static SingleBuiltPath parse(const StoreDirConfig & store, std::string_view);
+    nlohmann::json toJSON(const StoreDirConfig & store) const;
 };
 
 static inline ref<SingleBuiltPath> staticDrv(StorePath drvPath)
@@ -59,9 +59,9 @@ struct BuiltPathBuilt {
     ref<SingleBuiltPath> drvPath;
     std::map<std::string, StorePath> outputs;
 
-    std::string to_string(const Store & store) const;
-    static BuiltPathBuilt parse(const Store & store, std::string_view, std::string_view);
-    nlohmann::json toJSON(const Store & store) const;
+    std::string to_string(const StoreDirConfig & store) const;
+    static BuiltPathBuilt parse(const StoreDirConfig & store, std::string_view, std::string_view);
+    nlohmann::json toJSON(const StoreDirConfig & store) const;
 
     DECLARE_CMP(BuiltPathBuilt);
 };
@@ -89,7 +89,7 @@ struct BuiltPath : _BuiltPathRaw {
     StorePathSet outPaths() const;
     RealisedPath::Set toRealisedPaths(Store & store) const;
 
-    nlohmann::json toJSON(const Store & store) const;
+    nlohmann::json toJSON(const StoreDirConfig & store) const;
 };
 
 typedef std::vector<BuiltPath> BuiltPaths;

src/libcmd/command.cc

@@ -1,4 +1,5 @@
 #include "command.hh"
+#include "markdown.hh"
 #include "store-api.hh"
 #include "local-fs-store.hh"
 #include "derivations.hh"
@@ -34,6 +35,19 @@ nlohmann::json NixMultiCommand::toJSON()
     return MultiCommand::toJSON();
 }
 
+void NixMultiCommand::run()
+{
+    if (!command) {
+        std::set<std::string> subCommandTextLines;
+        for (auto & [name, _] : commands)
+            subCommandTextLines.insert(fmt("- `%s`", name));
+        std::string markdownError = fmt("`nix %s` requires a sub-command. Available sub-commands:\n\n%s\n",
+                commandName, concatStringsSep("\n", subCommandTextLines));
+        throw UsageError(renderMarkdownToTerminal(markdownError));
+    }
+    command->second->run();
+}
+
 StoreCommand::StoreCommand()
 {
 }

src/libcmd/command.hh

@@ -26,9 +26,13 @@ static constexpr Command::Category catNixInstallation = 102;
 
 static constexpr auto installablesCategory = "Options that change the interpretation of [installables](@docroot@/command-ref/new-cli/nix.md#installables)";
 
-struct NixMultiCommand : virtual MultiCommand, virtual Command
+struct NixMultiCommand : MultiCommand, virtual Command
 {
     nlohmann::json toJSON() override;
+
+    using MultiCommand::MultiCommand;
+
+    virtual void run() override;
 };
 
 // For the overloaded run methods

src/libcmd/common-eval-args.cc

@@ -141,7 +141,7 @@ MixEvalArgs::MixEvalArgs()
         .longName = "eval-store",
         .description =
           R"(
-            The [URL of the Nix store](@docroot@/command-ref/new-cli/nix3-help-stores.md#store-url-format)
+            The [URL of the Nix store](@docroot@/store/types/index.md#store-url-format)
             to use for evaluation, i.e. to store derivations (`.drv` files) and inputs referenced by them.
           )",
         .category = category,

src/libcmd/installables.cc

@@ -260,9 +260,10 @@ void SourceExprCommand::completeInstallable(AddCompletions & completions, std::s
 
             evalSettings.pureEval = false;
             auto state = getEvalState();
-            Expr *e = state->parseExprFromFile(
-                resolveExprPath(state->checkSourcePath(lookupFileArg(*state, *file)))
-                );
+            auto e =
+                state->parseExprFromFile(
+                    resolveExprPath(
+                        lookupFileArg(*state, *file)));
 
             Value root;
             state->eval(e, root);

src/libcmd/local.mk

@@ -12,4 +12,4 @@ libcmd_LDFLAGS = $(EDITLINE_LIBS) $(LOWDOWN_LIBS) -pthread
 
 libcmd_LIBS = libstore libutil libexpr libmain libfetchers
 
-$(eval $(call install-file-in, $(d)/nix-cmd.pc, $(libdir)/pkgconfig, 0644))
+$(eval $(call install-file-in, $(buildprefix)$(d)/nix-cmd.pc, $(libdir)/pkgconfig, 0644))

src/libcmd/repl.cc

@@ -43,7 +43,6 @@ extern "C" {
 #include "finally.hh"
 #include "markdown.hh"
 #include "local-fs-store.hh"
-#include "progress-bar.hh"
 #include "print.hh"
 
 #if HAVE_BOEHMGC
@@ -262,13 +261,11 @@ 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) {
+        // Hide the progress bar while waiting for user input, so that it won't interfere.
+        logger->pause();
         // When continuing input from previous lines, don't print a prompt, just align to the same
         // number of chars as the prompt.
         if (!getLine(input, input.empty() ? "nix-repl> " : "          ")) {
@@ -278,6 +275,7 @@ void NixRepl::mainLoop()
             logger->cout("");
             break;
         }
+        logger->resume();
         try {
             if (!removeWhitespace(input).empty() && !processLine(input)) return;
         } catch (ParseError & e) {

src/libexpr/eval-cache.cc

@@ -22,7 +22,7 @@ struct AttrDb
 {
     std::atomic_bool failed{false};
 
-    const Store & cfg;
+    const StoreDirConfig & cfg;
 
     struct State
     {
@@ -39,7 +39,7 @@ struct AttrDb
     SymbolTable & symbols;
 
     AttrDb(
-        const Store & cfg,
+        const StoreDirConfig & cfg,
         const Hash & fingerprint,
         SymbolTable & symbols)
         : cfg(cfg)
@@ -323,7 +323,7 @@ struct AttrDb
 };
 
 static std::shared_ptr<AttrDb> makeAttrDb(
-    const Store & cfg,
+    const StoreDirConfig & cfg,
     const Hash & fingerprint,
     SymbolTable & symbols)
 {

src/libexpr/eval-inline.hh

@@ -103,8 +103,10 @@ void EvalState::forceValue(Value & v, Callable getPos)
             throw;
         }
     }
-    else if (v.isApp())
-        callFunction(*v.app.left, *v.app.right, v, noPos);
+    else if (v.isApp()) {
+        PosIdx pos = getPos();
+        callFunction(*v.app.left, *v.app.right, v, pos);
+    }
     else if (v.isBlackhole())
         error("infinite recursion encountered").atPos(getPos()).template debugThrow<EvalError>();
 }
@@ -121,9 +123,9 @@ template <typename Callable>
 [[gnu::always_inline]]
 inline void EvalState::forceAttrs(Value & v, Callable getPos, std::string_view errorCtx)
 {
-    forceValue(v, noPos);
-    if (v.type() != nAttrs) {
     PosIdx pos = getPos();
+    forceValue(v, pos);
+    if (v.type() != nAttrs) {
         error("value is %1% while a set was expected", showType(v)).withTrace(pos, errorCtx).debugThrow<TypeError>();
     }
 }
@@ -132,7 +134,7 @@ inline void EvalState::forceAttrs(Value & v, Callable getPos, std::string_view e
 [[gnu::always_inline]]
 inline void EvalState::forceList(Value & v, const PosIdx pos, std::string_view errorCtx)
 {
-    forceValue(v, noPos);
+    forceValue(v, pos);
     if (!v.isList()) {
         error("value is %1% while a list was expected", showType(v)).withTrace(pos, errorCtx).debugThrow<TypeError>();
     }

src/libexpr/eval-settings.hh

@@ -68,6 +68,11 @@ struct EvalSettings : Config
           evaluation mode. For example, when set to
           `https://github.com/NixOS`, builtin functions such as `fetchGit` are
           allowed to access `https://github.com/NixOS/patchelf.git`.
+
+          Access is granted when
+          - the URI is equal to the prefix,
+          - or the URI is a subpath of the prefix,
+          - or the prefix is a URI scheme ended by a colon `:` and the URI has the same scheme.
         )"};
 
     Setting<bool> traceFunctionCalls{this, false, "trace-function-calls",

src/libexpr/eval.cc

@@ -14,8 +14,11 @@
 #include "profiles.hh"
 #include "print.hh"
 #include "fs-input-accessor.hh"
+#include "filtering-input-accessor.hh"
 #include "memory-input-accessor.hh"
 #include "signals.hh"
+#include "gc-small-vector.hh"
+#include "url.hh"
 
 #include <algorithm>
 #include <chrono>
@@ -31,6 +34,7 @@
 
 #include <sys/resource.h>
 #include <nlohmann/json.hpp>
+#include <boost/container/small_vector.hpp>
 
 #if HAVE_BOEHMGC
 
@@ -342,7 +346,7 @@ static Symbol getName(const AttrName & name, EvalState & state, Env & env)
     } else {
         Value nameValue;
         name.expr->eval(state, env, nameValue);
-        state.forceStringNoCtx(nameValue, noPos, "while evaluating an attribute name");
+        state.forceStringNoCtx(nameValue, name.expr->getPos(), "while evaluating an attribute name");
         return state.symbols.create(nameValue.string_view());
     }
 }
@@ -507,7 +511,16 @@ EvalState::EvalState(
     , sOutputSpecified(symbols.create("outputSpecified"))
     , repair(NoRepair)
     , emptyBindings(0)
-    , rootFS(makeFSInputAccessor(CanonPath::root))
+    , rootFS(
+        evalSettings.restrictEval || evalSettings.pureEval
+        ? ref<InputAccessor>(AllowListInputAccessor::create(makeFSInputAccessor(CanonPath::root), {},
+            [](const CanonPath & path) -> RestrictedPathError {
+                auto modeInformation = evalSettings.pureEval
+                    ? "in pure evaluation mode (use '--impure' to override)"
+                    : "in restricted mode";
+                throw RestrictedPathError("access to absolute path '%1%' is forbidden %2%", path, modeInformation);
+            }))
+        : makeFSInputAccessor(CanonPath::root))
     , corepkgsFS(makeMemoryInputAccessor())
     , internalFS(makeMemoryInputAccessor())
     , derivationInternal{corepkgsFS->addFile(
@@ -549,28 +562,10 @@ EvalState::EvalState(
             searchPath.elements.emplace_back(SearchPath::Elem::parse(i));
     }
 
-    if (evalSettings.restrictEval || evalSettings.pureEval) {
-        allowedPaths = PathSet();
-
-        for (auto & i : searchPath.elements) {
-            auto r = resolveSearchPathPath(i.path);
-            if (!r) continue;
-
-            auto path = std::move(*r);
-
-            if (store->isInStore(path)) {
-                try {
-                    StorePathSet closure;
-                    store->computeFSClosure(store->toStorePath(path).first, closure);
-                    for (auto & path : closure)
-                        allowPath(path);
-                } catch (InvalidPath &) {
-                    allowPath(path);
-                }
-            } else
-                allowPath(path);
-        }
-    }
+    /* Allow access to all paths in the search path. */
+    if (rootFS.dynamic_pointer_cast<AllowListInputAccessor>())
+        for (auto & i : searchPath.elements)
+            resolveSearchPathPath(i.path, true);
 
     corepkgsFS->addFile(
         CanonPath("fetchurl.nix"),
@@ -588,14 +583,14 @@ EvalState::~EvalState()
 
 void EvalState::allowPath(const Path & path)
 {
-    if (allowedPaths)
-        allowedPaths->insert(path);
+    if (auto rootFS2 = rootFS.dynamic_pointer_cast<AllowListInputAccessor>())
+        rootFS2->allowPath(CanonPath(path));
 }
 
 void EvalState::allowPath(const StorePath & storePath)
 {
-    if (allowedPaths)
-        allowedPaths->insert(store->toRealPath(storePath));
+    if (auto rootFS2 = rootFS.dynamic_pointer_cast<AllowListInputAccessor>())
+        rootFS2->allowPath(CanonPath(store->toRealPath(storePath)));
 }
 
 void EvalState::allowAndSetStorePathString(const StorePath & storePath, Value & v)
@@ -605,79 +600,57 @@ void EvalState::allowAndSetStorePathString(const StorePath & storePath, Value &
     mkStorePathString(storePath, v);
 }
 
-SourcePath EvalState::checkSourcePath(const SourcePath & path_)
+inline static bool isJustSchemePrefix(std::string_view prefix)
 {
-    // Don't check non-rootFS accessors, they're in a different namespace.
-    if (path_.accessor != ref<InputAccessor>(rootFS)) return path_;
-
-    if (!allowedPaths) return path_;
-
-    auto i = resolvedPaths.find(path_.path.abs());
-    if (i != resolvedPaths.end())
-        return i->second;
-
-    bool found = false;
-
-    /* First canonicalize the path without symlinks, so we make sure an
-     * attacker can't append ../../... to a path that would be in allowedPaths
-     * and thus leak symlink targets.
-     */
-    Path abspath = canonPath(path_.path.abs());
-
-    for (auto & i : *allowedPaths) {
-        if (isDirOrInDir(abspath, i)) {
-            found = true;
-            break;
-        }
+    return
+        !prefix.empty()
+        && prefix[prefix.size() - 1] == ':'
+        && isValidSchemeName(prefix.substr(0, prefix.size() - 1));
 }
 
-    if (!found) {
-        auto modeInformation = evalSettings.pureEval
-            ? "in pure eval mode (use '--impure' to override)"
-            : "in restricted mode";
-        throw RestrictedPathError("access to absolute path '%1%' is forbidden %2%", abspath, modeInformation);
+bool isAllowedURI(std::string_view uri, const Strings & allowedUris)
+{
+    /* 'uri' should be equal to a prefix, or in a subdirectory of a
+       prefix. Thus, the prefix https://github.co does not permit
+       access to https://github.com. */
+    for (auto & prefix : allowedUris) {
+        if (uri == prefix
+            // Allow access to subdirectories of the prefix.
+            || (uri.size() > prefix.size()
+                && prefix.size() > 0
+                && hasPrefix(uri, prefix)
+                && (
+                    // Allow access to subdirectories of the prefix.
+                    prefix[prefix.size() - 1] == '/'
+                    || uri[prefix.size()] == '/'
+
+                    // Allow access to whole schemes
+                    || isJustSchemePrefix(prefix)
+                    )
+                ))
+            return true;
     }
 
-    /* Resolve symlinks. */
-    debug("checking access to '%s'", abspath);
-    SourcePath path = rootPath(CanonPath(canonPath(abspath, true)));
-
-    for (auto & i : *allowedPaths) {
-        if (isDirOrInDir(path.path.abs(), i)) {
-            resolvedPaths.insert_or_assign(path_.path.abs(), path);
-            return path;
+    return false;
 }
-    }
-
-    throw RestrictedPathError("access to canonical path '%1%' is forbidden in restricted mode", path);
-}
-
 
 void EvalState::checkURI(const std::string & uri)
 {
     if (!evalSettings.restrictEval) return;
 
-    /* 'uri' should be equal to a prefix, or in a subdirectory of a
-       prefix. Thus, the prefix https://github.co does not permit
-       access to https://github.com. Note: this allows 'http://' and
-       'https://' as prefixes for any http/https URI. */
-    for (auto & prefix : evalSettings.allowedUris.get())
-        if (uri == prefix ||
-            (uri.size() > prefix.size()
-            && prefix.size() > 0
-            && hasPrefix(uri, prefix)
-            && (prefix[prefix.size() - 1] == '/' || uri[prefix.size()] == '/')))
-            return;
+    if (isAllowedURI(uri, evalSettings.allowedUris.get())) return;
 
     /* If the URI is a path, then check it against allowedPaths as
        well. */
     if (hasPrefix(uri, "/")) {
-        checkSourcePath(rootPath(CanonPath(uri)));
+        if (auto rootFS2 = rootFS.dynamic_pointer_cast<AllowListInputAccessor>())
+            rootFS2->checkAccess(CanonPath(uri));
         return;
     }
 
     if (hasPrefix(uri, "file://")) {
-        checkSourcePath(rootPath(CanonPath(std::string(uri, 7))));
+        if (auto rootFS2 = rootFS.dynamic_pointer_cast<AllowListInputAccessor>())
+            rootFS2->checkAccess(CanonPath(uri.substr(7)));
         return;
     }
 
@@ -1179,10 +1152,8 @@ Value * ExprPath::maybeThunk(EvalState & state, Env & env)
 }
 
 
-void EvalState::evalFile(const SourcePath & path_, Value & v, bool mustBeTrivial)
+void EvalState::evalFile(const SourcePath & path, Value & v, bool mustBeTrivial)
 {
-    auto path = checkSourcePath(path_);
-
     FileEvalCache::iterator i;
     if ((i = fileEvalCache.find(path)) != fileEvalCache.end()) {
         v = i->second;
@@ -1203,7 +1174,7 @@ void EvalState::evalFile(const SourcePath & path_, Value & v, bool mustBeTrivial
         e = j->second;
 
     if (!e)
-        e = parseExprFromFile(checkSourcePath(resolvedPath));
+        e = parseExprFromFile(resolvedPath);
 
     fileParseCache[resolvedPath] = e;
 
@@ -1512,7 +1483,7 @@ void ExprOpHasAttr::eval(EvalState & state, Env & env, Value & v)
     e->eval(state, env, vTmp);
 
     for (auto & i : attrPath) {
-        state.forceValue(*vAttrs, noPos);
+        state.forceValue(*vAttrs, getPos());
         Bindings::iterator j;
         auto name = getName(i, state, env);
         if (vAttrs->type() != nAttrs ||
@@ -1681,7 +1652,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                 if (countCalls) primOpCalls[name]++;
 
                 try {
-                    vCur.primOp->fun(*this, noPos, args, vCur);
+                    vCur.primOp->fun(*this, vCur.determinePos(noPos), args, vCur);
                 } catch (Error & e) {
                     addErrorTrace(e, pos, "while calling the '%1%' builtin", name);
                     throw;
@@ -1712,7 +1683,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                 /* We have all the arguments, so call the primop with
                    the previous and new arguments. */
 
-                Value * vArgs[arity];
+                Value * vArgs[maxPrimOpArity];
                 auto n = argsDone;
                 for (Value * arg = &vCur; arg->isPrimOpApp(); arg = arg->primOpApp.left)
                     vArgs[--n] = arg->primOpApp.right;
@@ -1729,7 +1700,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                     // 1. Unify this and above code. Heavily redundant.
                     // 2. Create a fake env (arg1, arg2, etc.) and a fake expr (arg1: arg2: etc: builtins.name arg1 arg2 etc)
                     //    so the debugger allows to inspect the wrong parameters passed to the builtin.
-                    primOp->primOp->fun(*this, noPos, vArgs, vCur);
+                    primOp->primOp->fun(*this, vCur.determinePos(noPos), vArgs, vCur);
                 } catch (Error & e) {
                     addErrorTrace(e, pos, "while calling the '%1%' builtin", name);
                     throw;
@@ -1775,11 +1746,11 @@ void ExprCall::eval(EvalState & state, Env & env, Value & v)
     // 4: about 60
     // 5: under 10
     // This excluded attrset lambdas (`{...}:`). Contributions of mixed lambdas appears insignificant at ~150 total.
-    Value * vArgs[args.size()];
+    SmallValueVector<4> vArgs(args.size());
     for (size_t i = 0; i < args.size(); ++i)
         vArgs[i] = args[i]->maybeThunk(state, env);
 
-    state.callFunction(vFun, args.size(), vArgs, v, pos);
+    state.callFunction(vFun, args.size(), vArgs.data(), v, pos);
 }
 
 
@@ -1837,7 +1808,7 @@ https://nixos.org/manual/nix/stable/language/constructs.html#functions.)", symbo
         }
     }
 
-    callFunction(fun, allocValue()->mkAttrs(attrs), res, noPos);
+    callFunction(fun, allocValue()->mkAttrs(attrs), res, pos);
 }
 
 
@@ -1873,7 +1844,7 @@ void ExprAssert::eval(EvalState & state, Env & env, Value & v)
 
 void ExprOpNot::eval(EvalState & state, Env & env, Value & v)
 {
-    v.mkBool(!state.evalBool(env, e, noPos, "in the argument of the not operator")); // XXX: FIXME: !
+    v.mkBool(!state.evalBool(env, e, getPos(), "in the argument of the not operator")); // XXX: FIXME: !
 }
 
 
@@ -2018,8 +1989,9 @@ void ExprConcatStrings::eval(EvalState & state, Env & env, Value & v)
         return result;
     };
 
-    Value values[es->size()];
-    Value * vTmpP = values;
+    // List of returned strings. References to these Values must NOT be persisted.
+    SmallTemporaryValueVector<conservativeStackReservation> values(es->size());
+    Value * vTmpP = values.data();
 
     for (auto & [i_pos, i] : *es) {
         Value & vTmp = *vTmpP++;
@@ -2313,7 +2285,7 @@ BackedStringView EvalState::coerceToString(
             std::string result;
             for (auto [n, v2] : enumerate(v.listItems())) {
                 try {
-                    result += *coerceToString(noPos, *v2, context,
+                    result += *coerceToString(pos, *v2, context,
                             "while evaluating one element of the list",
                             coerceMore, copyToStore, canonicalizePath);
                 } catch (Error & e) {
@@ -2460,8 +2432,8 @@ SingleDerivedPath EvalState::coerceToSingleDerivedPath(const PosIdx pos, Value &
 
 bool EvalState::eqValues(Value & v1, Value & v2, const PosIdx pos, std::string_view errorCtx)
 {
-    forceValue(v1, noPos);
-    forceValue(v2, noPos);
+    forceValue(v1, pos);
+    forceValue(v2, pos);
 
     /* !!! Hack to support some old broken code that relies on pointer
        equality tests between sets.  (Specifically, builderDefs calls

src/libexpr/eval.hh

@@ -30,7 +30,6 @@ class EvalState;
 class StorePath;
 struct SingleDerivedPath;
 enum RepairFlag : bool;
-struct FSInputAccessor;
 struct MemoryInputAccessor;
 
 
@@ -217,18 +216,12 @@ public:
      */
     RepairFlag repair;
 
-    /**
-     * The allowed filesystem paths in restricted or pure evaluation
-     * mode.
-     */
-    std::optional<PathSet> allowedPaths;
-
     Bindings emptyBindings;
 
     /**
      * The accessor for the root filesystem.
      */
-    const ref<FSInputAccessor> rootFS;
+    const ref<InputAccessor> rootFS;
 
     /**
      * The in-memory filesystem for <nix/...> paths.
@@ -342,11 +335,6 @@ private:
 
     std::map<std::string, std::optional<std::string>> searchPathResolved;
 
-    /**
-     * Cache used by checkSourcePath().
-     */
-    std::unordered_map<Path, SourcePath> resolvedPaths;
-
     /**
      * Cache used by prim_match().
      */
@@ -396,12 +384,6 @@ public:
      */
     void allowAndSetStorePathString(const StorePath & storePath, Value & v);
 
-    /**
-     * Check whether access to a path is allowed and throw an error if
-     * not. Otherwise return the canonicalised path.
-     */
-    SourcePath checkSourcePath(const SourcePath & path);
-
     void checkURI(const std::string & uri);
 
     /**
@@ -445,13 +427,15 @@ public:
     SourcePath findFile(const SearchPath & searchPath, const std::string_view path, const PosIdx pos = noPos);
 
     /**
-     * Try to resolve a search path value (not the optional key part)
+     * Try to resolve a search path value (not the optional key part).
      *
      * If the specified search path element is a URI, download it.
      *
      * If it is not found, return `std::nullopt`
      */
-    std::optional<std::string> resolveSearchPathPath(const SearchPath::Path & path);
+    std::optional<std::string> resolveSearchPathPath(
+        const SearchPath::Path & elem,
+        bool initAccessControl = false);
 
     /**
      * Evaluate an expression to normal form
@@ -756,6 +740,13 @@ public:
      */
     [[nodiscard]] StringMap realiseContext(const NixStringContext & context);
 
+    /* Call the binary path filter predicate used builtins.path etc. */
+    bool callPathFilter(
+        Value * filterFun,
+        const SourcePath & path,
+        std::string_view pathArg,
+        PosIdx pos);
+
 private:
 
     /**
@@ -841,6 +832,11 @@ std::string showType(const Value & v);
  */
 SourcePath resolveExprPath(SourcePath path);
 
+/**
+ * Whether a URI is allowed, assuming restrictEval is enabled
+ */
+bool isAllowedURI(std::string_view uri, const Strings & allowedPaths);
+
 struct InvalidPathError : EvalError
 {
     Path path;

src/libexpr/flake/flake.cc

@@ -904,7 +904,7 @@ Fingerprint LockedFlake::getFingerprint() const
     // FIXME: as an optimization, if the flake contains a lock file
     // and we haven't changed it, then it's sufficient to use
     // flake.sourceInfo.storePath for the fingerprint.
-    return hashString(htSHA256,
+    return hashString(HashAlgorithm::SHA256,
         fmt("%s;%s;%d;%d;%s",
             flake.storePath.to_string(),
             flake.lockedRef.subdir,

src/libexpr/flake/flakeref.cc

@@ -90,7 +90,7 @@ std::pair<FlakeRef, std::string> parsePathFlakeRefWithFragment(
         fragment = percentDecode(url.substr(fragmentStart+1));
     }
     if (pathEnd != std::string::npos && fragmentStart != std::string::npos) {
-        query = decodeQuery(url.substr(pathEnd+1, fragmentStart));
+        query = decodeQuery(url.substr(pathEnd+1, fragmentStart-pathEnd-1));
     }
 
     if (baseDir) {

src/libexpr/gc-small-vector.hh

@@ -0,0 +1,42 @@
+#pragma once
+
+#include <boost/container/small_vector.hpp>
+
+#if HAVE_BOEHMGC
+
+#include <gc/gc.h>
+#include <gc/gc_cpp.h>
+#include <gc/gc_allocator.h>
+
+#endif
+
+namespace nix {
+
+struct Value;
+
+/**
+ * A GC compatible vector that may used a reserved portion of `nItems` on the stack instead of allocating on the heap.
+ */
+#if HAVE_BOEHMGC
+template <typename T, size_t nItems>
+using SmallVector = boost::container::small_vector<T, nItems, traceable_allocator<T>>;
+#else
+template <typename T, size_t nItems>
+using SmallVector = boost::container::small_vector<T, nItems>;
+#endif
+
+/**
+ * A vector of value pointers. See `SmallVector`.
+ */
+template <size_t nItems>
+using SmallValueVector = SmallVector<Value *, nItems>;
+
+/**
+ * A vector of values that must not be referenced after the vector is destroyed.
+ *
+ * See also `SmallValueVector`.
+ */
+template <size_t nItems>
+using SmallTemporaryValueVector = SmallVector<Value, nItems>;
+
+}

src/libexpr/local.mk

@@ -16,7 +16,7 @@ libexpr_CXXFLAGS += -I src/libutil -I src/libstore -I src/libfetchers -I src/lib
 
 libexpr_LIBS = libutil libstore libfetchers
 
-libexpr_LDFLAGS += -lboost_context -lboost_regex -pthread
+libexpr_LDFLAGS += -lboost_context -pthread
 ifdef HOST_LINUX
  libexpr_LDFLAGS += -ldl
 endif
@@ -36,7 +36,7 @@ $(d)/lexer-tab.cc $(d)/lexer-tab.hh: $(d)/lexer.l
 
 clean-files += $(d)/parser-tab.cc $(d)/parser-tab.hh $(d)/lexer-tab.cc $(d)/lexer-tab.hh
 
-$(eval $(call install-file-in, $(d)/nix-expr.pc, $(libdir)/pkgconfig, 0644))
+$(eval $(call install-file-in, $(buildprefix)$(d)/nix-expr.pc, $(libdir)/pkgconfig, 0644))
 
 $(foreach i, $(wildcard src/libexpr/value/*.hh), \
   $(eval $(call install-file-in, $(i), $(includedir)/nix/value, 0644)))
@@ -47,4 +47,4 @@ $(d)/primops.cc: $(d)/imported-drv-to-derivation.nix.gen.hh
 
 $(d)/eval.cc: $(d)/primops/derivation.nix.gen.hh $(d)/fetchurl.nix.gen.hh $(d)/flake/call-flake.nix.gen.hh
 
-src/libexpr/primops/fromTOML.o:	ERROR_SWITCH_ENUM =
+$(buildprefix)src/libexpr/primops/fromTOML.o:	ERROR_SWITCH_ENUM =

src/libexpr/nixexpr.hh

@@ -405,6 +405,7 @@ struct ExprOpNot : Expr
 {
     Expr * e;
     ExprOpNot(Expr * e) : e(e) { };
+    PosIdx getPos() const override { return e->getPos(); }
     COMMON_METHODS
 };
 

src/libexpr/parser.y

@@ -692,16 +692,17 @@ SourcePath resolveExprPath(SourcePath path)
 
     /* If `path' is a symlink, follow it.  This is so that relative
        path references work. */
-    while (true) {
+    while (!path.path.isRoot()) {
         // Basic cycle/depth limit to avoid infinite loops.
         if (++followCount >= maxFollow)
             throw Error("too many symbolic links encountered while traversing the path '%s'", path);
-        if (path.lstat().type != InputAccessor::tSymlink) break;
-        path = {path.accessor, CanonPath(path.readLink(), path.path.parent().value_or(CanonPath::root))};
+        auto p = path.parent().resolveSymlinks() + path.baseName();
+        if (p.lstat().type != InputAccessor::tSymlink) break;
+        path = {path.accessor, CanonPath(p.readLink(), path.path.parent().value_or(CanonPath::root))};
     }
 
     /* If `path' refers to a directory, append `/default.nix'. */
-    if (path.lstat().type == InputAccessor::tDirectory)
+    if (path.resolveSymlinks().lstat().type == InputAccessor::tDirectory)
         return path + "default.nix";
 
     return path;
@@ -716,7 +717,7 @@ Expr * EvalState::parseExprFromFile(const SourcePath & path)
 
 Expr * EvalState::parseExprFromFile(const SourcePath & path, std::shared_ptr<StaticEnv> & staticEnv)
 {
-    auto buffer = path.readFile();
+    auto buffer = path.resolveSymlinks().readFile();
     // readFile hopefully have left some extra space for terminators
     buffer.append("\0\0", 2);
     return parse(buffer.data(), buffer.size(), Pos::Origin(path), path.parent(), staticEnv);
@@ -783,7 +784,7 @@ SourcePath EvalState::findFile(const SearchPath & searchPath, const std::string_
 }
 
 
-std::optional<std::string> EvalState::resolveSearchPathPath(const SearchPath::Path & value0)
+std::optional<std::string> EvalState::resolveSearchPathPath(const SearchPath::Path & value0, bool initAccessControl)
 {
     auto & value = value0.s;
     auto i = searchPathResolved.find(value);
@@ -800,7 +801,6 @@ std::optional<std::string> EvalState::resolveSearchPathPath(const SearchPath::Pa
             logWarning({
                 .msg = hintfmt("Nix search path entry '%1%' cannot be downloaded, ignoring", value)
             });
-            res = std::nullopt;
         }
     }
 
@@ -814,6 +814,20 @@ std::optional<std::string> EvalState::resolveSearchPathPath(const SearchPath::Pa
 
     else {
         auto path = absPath(value);
+
+        /* Allow access to paths in the search path. */
+        if (initAccessControl) {
+            allowPath(path);
+            if (store->isInStore(path)) {
+                try {
+                    StorePathSet closure;
+                    store->computeFSClosure(store->toStorePath(path).first, closure);
+                    for (auto & p : closure)
+                        allowPath(p);
+                } catch (InvalidPath &) { }
+            }
+        }
+
         if (pathExists(path))
             res = { path };
         else {
@@ -829,7 +843,7 @@ std::optional<std::string> EvalState::resolveSearchPathPath(const SearchPath::Pa
     else
         debug("failed to resolve search path element '%s'", value);
 
-    searchPathResolved[value] = res;
+    searchPathResolved.emplace(value, res);
     return res;
 }
 

src/libexpr/primops.cc

@@ -4,6 +4,7 @@
 #include "eval-inline.hh"
 #include "eval.hh"
 #include "eval-settings.hh"
+#include "gc-small-vector.hh"
 #include "globals.hh"
 #include "json-to-value.hh"
 #include "names.hh"
@@ -14,9 +15,9 @@
 #include "value-to-json.hh"
 #include "value-to-xml.hh"
 #include "primops.hh"
+#include "fs-input-accessor.hh"
 
 #include <boost/container/small_vector.hpp>
-#include <boost/regex.hpp>
 #include <nlohmann/json.hpp>
 
 #include <sys/types.h>
@@ -25,6 +26,7 @@
 
 #include <algorithm>
 #include <cstring>
+#include <regex>
 #include <dlfcn.h>
 
 #include <cmath>
@@ -89,9 +91,8 @@ StringMap EvalState::realiseContext(const NixStringContext & context)
         for (auto & [outputName, outputPath] : outputs) {
             /* Add the output of this derivations to the allowed
                paths. */
-            if (allowedPaths) {
-                allowPath(outputPath);
-            }
+            allowPath(store->toRealPath(outputPath));
+
             /* Get all the output paths corresponding to the placeholders we had */
             if (experimentalFeatureSettings.isEnabled(Xp::CaDerivations)) {
                 res.insert_or_assign(
@@ -109,27 +110,19 @@ StringMap EvalState::realiseContext(const NixStringContext & context)
     return res;
 }
 
-struct RealisePathFlags {
-    // Whether to check that the path is allowed in pure eval mode
-    bool checkForPureEval = true;
-};
-
-static SourcePath realisePath(EvalState & state, const PosIdx pos, Value & v, const RealisePathFlags flags = {})
+static SourcePath realisePath(EvalState & state, const PosIdx pos, Value & v, bool resolveSymlinks = true)
 {
     NixStringContext context;
 
     auto path = state.coerceToPath(noPos, v, context, "while realising the context of a path");
 
     try {
-        if (!context.empty()) {
+        if (!context.empty() && path.accessor == state.rootFS) {
             auto rewrites = state.realiseContext(context);
             auto realPath = state.toRealPath(rewriteStrings(path.path.abs(), rewrites), context);
-            return {path.accessor, CanonPath(realPath)};
+            path = {path.accessor, CanonPath(realPath)};
         }
-
-        return flags.checkForPureEval
-            ? state.checkSourcePath(path)
-            : path;
+        return resolveSymlinks ? path.resolveSymlinks() : path;
     } catch (Error & e) {
         e.addTrace(state.positions[pos], "while realising the context of path '%s'", path);
         throw;
@@ -169,7 +162,7 @@ static void mkOutputString(
    argument. */
 static void import(EvalState & state, const PosIdx pos, Value & vPath, Value * vScope, Value & v)
 {
-    auto path = realisePath(state, pos, vPath);
+    auto path = realisePath(state, pos, vPath, false);
     auto path2 = path.path.abs();
 
     // FIXME
@@ -1316,7 +1309,7 @@ drvName, Bindings * attrs, Value & v)
                 .errPos = state.positions[noPos]
             }));
 
-        auto h = newHashAllowEmpty(*outputHash, parseHashTypeOpt(outputHashAlgo));
+        auto h = newHashAllowEmpty(*outputHash, parseHashAlgoOpt(outputHashAlgo));
 
         auto method = ingestionMethod.value_or(FileIngestionMethod::Flat);
 
@@ -1338,7 +1331,7 @@ drvName, Bindings * attrs, Value & v)
                 .errPos = state.positions[noPos]
             });
 
-        auto ht = parseHashTypeOpt(outputHashAlgo).value_or(htSHA256);
+        auto ha = parseHashAlgoOpt(outputHashAlgo).value_or(HashAlgorithm::SHA256);
         auto method = ingestionMethod.value_or(FileIngestionMethod::Recursive);
 
         for (auto & i : outputs) {
@@ -1347,13 +1340,13 @@ drvName, Bindings * attrs, Value & v)
                 drv.outputs.insert_or_assign(i,
                     DerivationOutput::Impure {
                         .method = method,
-                        .hashType = ht,
+                        .hashAlgo = ha,
                     });
             else
                 drv.outputs.insert_or_assign(i,
                     DerivationOutput::CAFloating {
                         .method = method,
-                        .hashType = ht,
+                        .hashAlgo = ha,
                     });
         }
     }
@@ -1492,7 +1485,7 @@ static void prim_storePath(EvalState & state, const PosIdx pos, Value * * args,
         }));
 
     NixStringContext context;
-    auto path = state.checkSourcePath(state.coerceToPath(pos, *args[0], context, "while evaluating the first argument passed to 'builtins.storePath'")).path;
+    auto path = state.coerceToPath(pos, *args[0], context, "while evaluating the first argument passed to 'builtins.storePath'").path;
     /* Resolve symlinks in ‘path’, unless ‘path’ itself is a symlink
        directly in the store.  The latter condition is necessary so
        e.g. nix-push does the right thing. */
@@ -1532,29 +1525,19 @@ static RegisterPrimOp primop_storePath({
 
 static void prim_pathExists(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
+    try {
         auto & arg = *args[0];
 
-    /* We don’t check the path right now, because we don’t want to
-       throw if the path isn’t allowed, but just return false (and we
-       can’t just catch the exception here because we still want to
-       throw if something in the evaluation of `arg` tries to
-       access an unauthorized path). */
-    auto path = realisePath(state, pos, arg, { .checkForPureEval = false });
+        auto path = realisePath(state, pos, arg);
 
         /* SourcePath doesn't know about trailing slash. */
         auto mustBeDir = arg.type() == nString
             && (arg.string_view().ends_with("/")
                 || arg.string_view().ends_with("/."));
 
-    try {
-        auto checked = state.checkSourcePath(path);
-        auto st = checked.maybeLstat();
+        auto st = path.maybeLstat();
         auto exists = st && (!mustBeDir || st->type == SourceAccessor::tDirectory);
         v.mkBool(exists);
-    } catch (SysError & e) {
-        /* Don't give away info from errors while canonicalising
-           ‘path’ in restricted mode. */
-        v.mkBool(false);
     } catch (RestrictedPathError & e) {
         v.mkBool(false);
     }
@@ -1698,7 +1681,7 @@ static void prim_findFile(EvalState & state, const PosIdx pos, Value * * args, V
 
     auto path = state.forceStringNoCtx(*args[1], pos, "while evaluating the second argument passed to builtins.findFile");
 
-    v.mkPath(state.checkSourcePath(state.findFile(searchPath, path, pos)));
+    v.mkPath(state.findFile(searchPath, path, pos));
 }
 
 static RegisterPrimOp primop_findFile(PrimOp {
@@ -1753,17 +1736,17 @@ static RegisterPrimOp primop_findFile(PrimOp {
 /* Return the cryptographic hash of a file in base-16. */
 static void prim_hashFile(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    auto type = state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.hashFile");
-    std::optional<HashType> ht = parseHashType(type);
-    if (!ht)
+    auto algo = state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.hashFile");
+    std::optional<HashAlgorithm> ha = parseHashAlgo(algo);
+    if (!ha)
         state.debugThrowLastTrace(Error({
-            .msg = hintfmt("unknown hash type '%1%'", type),
+            .msg = hintfmt("unknown hash algo '%1%'", algo),
             .errPos = state.positions[pos]
         }));
 
     auto path = realisePath(state, pos, *args[1]);
 
-    v.mkString(hashString(*ht, path.readFile()).to_string(HashFormat::Base16, false));
+    v.mkString(hashString(*ha, path.readFile()).to_string(HashFormat::Base16, false));
 }
 
 static RegisterPrimOp primop_hashFile({
@@ -1788,7 +1771,7 @@ static std::string_view fileTypeToString(InputAccessor::Type type)
 
 static void prim_readFileType(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    auto path = realisePath(state, pos, *args[0]);
+    auto path = realisePath(state, pos, *args[0], false);
     /* Retrieve the directory entry type and stringize it. */
     v.mkString(fileTypeToString(path.lstat().type));
 }
@@ -2177,11 +2160,35 @@ static RegisterPrimOp primop_toFile({
     .fun = prim_toFile,
 });
 
+bool EvalState::callPathFilter(
+    Value * filterFun,
+    const SourcePath & path,
+    std::string_view pathArg,
+    PosIdx pos)
+{
+    auto st = path.lstat();
+
+    /* Call the filter function.  The first argument is the path, the
+       second is a string indicating the type of the file. */
+    Value arg1;
+    arg1.mkString(pathArg);
+
+    Value arg2;
+    // assert that type is not "unknown"
+    arg2.mkString(fileTypeToString(st.type));
+
+    Value * args []{&arg1, &arg2};
+    Value res;
+    callFunction(*filterFun, 2, args, res, pos);
+
+    return forceBool(res, pos, "while evaluating the return value of the path filter function");
+}
+
 static void addPath(
     EvalState & state,
     const PosIdx pos,
     std::string_view name,
-    Path path,
+    SourcePath path,
     Value * filterFun,
     FileIngestionMethod method,
     const std::optional<Hash> expectedHash,
@@ -2189,48 +2196,29 @@ static void addPath(
     const NixStringContext & context)
 {
     try {
+        StorePathSet refs;
+
+        if (path.accessor == state.rootFS && state.store->isInStore(path.path.abs())) {
             // FIXME: handle CA derivation outputs (where path needs to
             // be rewritten to the actual output).
             auto rewrites = state.realiseContext(context);
-        path = state.toRealPath(rewriteStrings(path, rewrites), context);
+            path = {state.rootFS, CanonPath(state.toRealPath(rewriteStrings(path.path.abs(), rewrites), context))};
 
-        StorePathSet refs;
-
-        if (state.store->isInStore(path)) {
             try {
-                auto [storePath, subPath] = state.store->toStorePath(path);
+                auto [storePath, subPath] = state.store->toStorePath(path.path.abs());
                 // FIXME: we should scanForReferences on the path before adding it
                 refs = state.store->queryPathInfo(storePath)->references;
-                path = state.store->toRealPath(storePath) + subPath;
+                path = {state.rootFS, CanonPath(state.store->toRealPath(storePath) + subPath)};
             } catch (Error &) { // FIXME: should be InvalidPathError
             }
         }
 
-        path = evalSettings.pureEval && expectedHash
-            ? path
-            : state.checkSourcePath(state.rootPath(CanonPath(path))).path.abs();
-
-        PathFilter filter = filterFun ? ([&](const Path & path) {
-            auto st = lstat(path);
-
-            /* Call the filter function.  The first argument is the path,
-               the second is a string indicating the type of the file. */
-            Value arg1;
-            arg1.mkString(path);
-
-            Value arg2;
-            arg2.mkString(
-                S_ISREG(st.st_mode) ? "regular" :
-                S_ISDIR(st.st_mode) ? "directory" :
-                S_ISLNK(st.st_mode) ? "symlink" :
-                "unknown" /* not supported, will fail! */);
-
-            Value * args []{&arg1, &arg2};
-            Value res;
-            state.callFunction(*filterFun, 2, args, res, pos);
-
-            return state.forceBool(res, pos, "while evaluating the return value of the path filter function");
-        }) : defaultPathFilter;
+        std::unique_ptr<PathFilter> filter;
+        if (filterFun)
+            filter = std::make_unique<PathFilter>([&](const Path & p) {
+                auto p2 = CanonPath(p);
+                return state.callPathFilter(filterFun, {path.accessor, p2}, p2.abs(), pos);
+            });
 
         std::optional<StorePath> expectedStorePath;
         if (expectedHash)
@@ -2241,7 +2229,7 @@ static void addPath(
             });
 
         if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
-            auto dstPath = state.rootPath(CanonPath(path)).fetchToStore(state.store, name, method, &filter, state.repair);
+            auto dstPath = path.fetchToStore(state.store, name, method, filter.get(), state.repair);
             if (expectedHash && expectedStorePath != dstPath)
                 state.debugThrowLastTrace(Error("store path mismatch in (possibly filtered) path added from '%s'", path));
             state.allowAndSetStorePathString(dstPath, v);
@@ -2260,7 +2248,8 @@ static void prim_filterSource(EvalState & state, const PosIdx pos, Value * * arg
     auto path = state.coerceToPath(pos, *args[1], context,
         "while evaluating the second argument (the path to filter) passed to 'builtins.filterSource'");
     state.forceFunction(*args[0], pos, "while evaluating the first argument passed to builtins.filterSource");
-    addPath(state, pos, path.baseName(), path.path.abs(), args[0], FileIngestionMethod::Recursive, std::nullopt, v, context);
+
+    addPath(state, pos, path.baseName(), path, args[0], FileIngestionMethod::Recursive, std::nullopt, v, context);
 }
 
 static RegisterPrimOp primop_filterSource({
@@ -2340,7 +2329,7 @@ static void prim_path(EvalState & state, const PosIdx pos, Value * * args, Value
         else if (n == "recursive")
             method = FileIngestionMethod { state.forceBool(*attr.value, attr.pos, "while evaluating the `recursive` attribute passed to builtins.path") };
         else if (n == "sha256")
-            expectedHash = newHashAllowEmpty(state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the `sha256` attribute passed to builtins.path"), htSHA256);
+            expectedHash = newHashAllowEmpty(state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the `sha256` attribute passed to builtins.path"), HashAlgorithm::SHA256);
         else
             state.debugThrowLastTrace(EvalError({
                 .msg = hintfmt("unsupported argument '%1%' to 'addPath'", state.symbols[attr.name]),
@@ -2355,7 +2344,7 @@ static void prim_path(EvalState & state, const PosIdx pos, Value * * args, Value
     if (name.empty())
         name = path->baseName();
 
-    addPath(state, pos, name, path->path.abs(), filterFun, method, expectedHash, v, context);
+    addPath(state, pos, name, *path, filterFun, method, expectedHash, v, context);
 }
 
 static RegisterPrimOp primop_path({
@@ -2729,7 +2718,7 @@ static void prim_catAttrs(EvalState & state, const PosIdx pos, Value * * args, V
     auto attrName = state.symbols.create(state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.catAttrs"));
     state.forceList(*args[1], pos, "while evaluating the second argument passed to builtins.catAttrs");
 
-    Value * res[args[1]->listSize()];
+    SmallValueVector<nonRecursiveStackReservation> res(args[1]->listSize());
     size_t found = 0;
 
     for (auto v2 : args[1]->listItems()) {
@@ -3064,8 +3053,7 @@ static void prim_filter(EvalState & state, const PosIdx pos, Value * * args, Val
 
     state.forceFunction(*args[0], pos, "while evaluating the first argument passed to builtins.filter");
 
-    // FIXME: putting this on the stack is risky.
-    Value * vs[args[1]->listSize()];
+    SmallValueVector<nonRecursiveStackReservation> vs(args[1]->listSize());
     size_t k = 0;
 
     bool same = true;
@@ -3461,7 +3449,8 @@ static void prim_concatMap(EvalState & state, const PosIdx pos, Value * * args,
     state.forceList(*args[1], pos, "while evaluating the second argument passed to builtins.concatMap");
     auto nrLists = args[1]->listSize();
 
-    Value lists[nrLists];
+    // List of returned lists before concatenation. References to these Values must NOT be persisted.
+    SmallTemporaryValueVector<conservativeStackReservation> lists(nrLists);
     size_t len = 0;
 
     for (unsigned int n = 0; n < nrLists; ++n) {
@@ -3765,18 +3754,18 @@ static RegisterPrimOp primop_stringLength({
 /* Return the cryptographic hash of a string in base-16. */
 static void prim_hashString(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 {
-    auto type = state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.hashString");
-    std::optional<HashType> ht = parseHashType(type);
-    if (!ht)
+    auto algo = state.forceStringNoCtx(*args[0], pos, "while evaluating the first argument passed to builtins.hashString");
+    std::optional<HashAlgorithm> ha = parseHashAlgo(algo);
+    if (!ha)
         state.debugThrowLastTrace(Error({
-            .msg = hintfmt("unknown hash type '%1%'", type),
+            .msg = hintfmt("unknown hash algo '%1%'", algo),
             .errPos = state.positions[pos]
         }));
 
     NixStringContext context; // discarded
     auto s = state.forceString(*args[1], context, pos, "while evaluating the second argument passed to builtins.hashString");
 
-    v.mkString(hashString(*ht, s).to_string(HashFormat::Base16, false));
+    v.mkString(hashString(*ha, s).to_string(HashFormat::Base16, false));
 }
 
 static RegisterPrimOp primop_hashString({
@@ -3799,15 +3788,15 @@ static void prim_convertHash(EvalState & state, const PosIdx pos, Value * * args
     auto hash = state.forceStringNoCtx(*iteratorHash->value, pos, "while evaluating the attribute 'hash'");
 
     Bindings::iterator iteratorHashAlgo = inputAttrs->find(state.symbols.create("hashAlgo"));
-    std::optional<HashType> ht = std::nullopt;
+    std::optional<HashAlgorithm> ha = std::nullopt;
     if (iteratorHashAlgo != inputAttrs->end()) {
-        ht = parseHashType(state.forceStringNoCtx(*iteratorHashAlgo->value, pos, "while evaluating the attribute 'hashAlgo'"));
+        ha = parseHashAlgo(state.forceStringNoCtx(*iteratorHashAlgo->value, pos, "while evaluating the attribute 'hashAlgo'"));
     }
 
     Bindings::iterator iteratorToHashFormat = getAttr(state, state.symbols.create("toHashFormat"), args[0]->attrs, "while locating the attribute 'toHashFormat'");
     HashFormat hf = parseHashFormat(state.forceStringNoCtx(*iteratorToHashFormat->value, pos, "while evaluating the attribute 'toHashFormat'"));
 
-    v.mkString(Hash::parseAny(hash, ht).to_string(hf, hf == HashFormat::SRI));
+    v.mkString(Hash::parseAny(hash, ha).to_string(hf, hf == HashFormat::SRI));
 }
 
 static RegisterPrimOp primop_convertHash({
@@ -3836,7 +3825,8 @@ static RegisterPrimOp primop_convertHash({
 
         The format of the resulting hash. Must be one of
         - `"base16"`
-        - `"base32"`
+        - `"nix32"`
+        - `"base32"` (deprecated alias for `"nix32"`)
         - `"base64"`
         - `"sri"`
 
@@ -3885,30 +3875,19 @@ static RegisterPrimOp primop_convertHash({
     .fun = prim_convertHash,
 });
 
-// regex aliases, switch between boost and std
-using regex = boost::regex;
-using regex_error = boost::regex_error;
-using cmatch = boost::cmatch;
-using cregex_iterator = boost::cregex_iterator;
-namespace regex_constants = boost::regex_constants;
-// overloaded function alias
-constexpr auto regex_match = [] (auto &&...args) {
-    return boost::regex_match(std::forward<decltype(args)>(args)...);
- };
-
 struct RegexCache
 {
     // TODO use C++20 transparent comparison when available
-    std::unordered_map<std::string_view, regex> cache;
+    std::unordered_map<std::string_view, std::regex> cache;
     std::list<std::string> keys;
 
-    regex get(std::string_view re)
+    std::regex get(std::string_view re)
     {
         auto it = cache.find(re);
         if (it != cache.end())
             return it->second;
         keys.emplace_back(re);
-        return cache.emplace(keys.back(), regex(keys.back(), regex::extended)).first->second;
+        return cache.emplace(keys.back(), std::regex(keys.back(), std::regex::extended)).first->second;
     }
 };
 
@@ -3928,8 +3907,8 @@ void prim_match(EvalState & state, const PosIdx pos, Value * * args, Value & v)
         NixStringContext context;
         const auto str = state.forceString(*args[1], context, pos, "while evaluating the second argument passed to builtins.match");
 
-        cmatch match;
-        if (!regex_match(str.begin(), str.end(), match, regex)) {
+        std::cmatch match;
+        if (!std::regex_match(str.begin(), str.end(), match, regex)) {
             v.mkNull();
             return;
         }
@@ -3944,8 +3923,8 @@ void prim_match(EvalState & state, const PosIdx pos, Value * * args, Value & v)
                 (v.listElems()[i] = state.allocValue())->mkString(match[i + 1].str());
         }
 
-    } catch (regex_error & e) {
-        if (e.code() == regex_constants::error_space) {
+    } catch (std::regex_error & e) {
+        if (e.code() == std::regex_constants::error_space) {
             // limit is _GLIBCXX_REGEX_STATE_LIMIT for libstdc++
             state.debugThrowLastTrace(EvalError({
                 .msg = hintfmt("memory limit exceeded by regular expression '%s'", re),
@@ -4008,8 +3987,8 @@ void prim_split(EvalState & state, const PosIdx pos, Value * * args, Value & v)
         NixStringContext context;
         const auto str = state.forceString(*args[1], context, pos, "while evaluating the second argument passed to builtins.split");
 
-        auto begin = cregex_iterator(str.begin(), str.end(), regex);
-        auto end = cregex_iterator();
+        auto begin = std::cregex_iterator(str.begin(), str.end(), regex);
+        auto end = std::cregex_iterator();
 
         // Any matches results are surrounded by non-matching results.
         const size_t len = std::distance(begin, end);
@@ -4048,8 +4027,8 @@ void prim_split(EvalState & state, const PosIdx pos, Value * * args, Value & v)
 
         assert(idx == 2 * len + 1);
 
-    } catch (regex_error & e) {
-        if (e.code() == regex_constants::error_space) {
+    } catch (std::regex_error & e) {
+        if (e.code() == std::regex_constants::error_space) {
             // limit is _GLIBCXX_REGEX_STATE_LIMIT for libstdc++
             state.debugThrowLastTrace(EvalError({
                 .msg = hintfmt("memory limit exceeded by regular expression '%s'", re),
@@ -4410,7 +4389,7 @@ void EvalState::createBaseEnv()
     addConstant("__currentSystem", v, {
         .type = nString,
         .doc = R"(
-          The value of the [`system` configuration option](@docroot@/command-ref/conf-file.md#conf-pure-eval).
+          The value of the [`system` configuration option](@docroot@/command-ref/conf-file.md#conf-system).
 
           It can be used to set the `system` attribute for [`builtins.derivation`](@docroot@/language/derivations.md) such that the resulting derivation can be built on the same system that evaluates the Nix expression:
 
@@ -4459,7 +4438,7 @@ void EvalState::createBaseEnv()
         .doc = R"(
           Logical file system location of the [Nix store](@docroot@/glossary.md#gloss-store) currently in use.
 
-          This value is determined by the `store` parameter in [Store URLs](@docroot@/command-ref/new-cli/nix3-help-stores.md):
+          This value is determined by the `store` parameter in [Store URLs](@docroot@/store/types/index.md#store-url-format):
 
           ```shell-session
           $ nix-instantiate --store 'dummy://?store=/blah' --eval --expr builtins.storeDir

src/libexpr/primops/fetchClosure.cc

@@ -1,5 +1,6 @@
 #include "primops.hh"
 #include "store-api.hh"
+#include "realisation.hh"
 #include "make-content-addressed.hh"
 #include "url.hh"
 

src/libexpr/primops/fetchMercurial.cc

@@ -31,7 +31,7 @@ static void prim_fetchMercurial(EvalState & state, const PosIdx pos, Value * * a
                 // be both a revision or a branch/tag name.
                 auto value = state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the `rev` attribute passed to builtins.fetchMercurial");
                 if (std::regex_match(value.begin(), value.end(), revRegex))
-                    rev = Hash::parseAny(value, htSHA1);
+                    rev = Hash::parseAny(value, HashAlgorithm::SHA1);
                 else
                     ref = value;
             }
@@ -79,7 +79,7 @@ static void prim_fetchMercurial(EvalState & state, const PosIdx pos, Value * * a
         attrs2.alloc("branch").mkString(*input2.getRef());
     // Backward compatibility: set 'rev' to
     // 0000000000000000000000000000000000000000 for a dirty tree.
-    auto rev2 = input2.getRev().value_or(Hash(htSHA1));
+    auto rev2 = input2.getRev().value_or(Hash(HashAlgorithm::SHA1));
     attrs2.alloc("rev").mkString(rev2.gitRev());
     attrs2.alloc("shortRev").mkString(rev2.gitRev().substr(0, 12));
     if (auto revCount = input2.getRevCount())

src/libexpr/primops/fetchTree.cc

@@ -46,7 +46,7 @@ void emitTreeAttrs(
             attrs.alloc("shortRev").mkString(rev->gitShortRev());
         } else if (emptyRevFallback) {
             // Backwards compat for `builtins.fetchGit`: dirty repos return an empty sha1 as rev
-            auto emptyHash = Hash(htSHA1);
+            auto emptyHash = Hash(HashAlgorithm::SHA1);
             attrs.alloc("rev").mkString(emptyHash.gitRev());
             attrs.alloc("shortRev").mkString(emptyHash.gitShortRev());
         }
@@ -187,45 +187,215 @@ static RegisterPrimOp primop_fetchTree({
     .name = "fetchTree",
     .args = {"input"},
     .doc = R"(
-      Fetch a source tree or a plain file using one of the supported backends.
-      *input* must be a [flake reference](@docroot@/command-ref/new-cli/nix3-flake.md#flake-references), either in attribute set representation or in the URL-like syntax.
-      The input should be "locked", that is, it should contain a commit hash or content hash unless impure evaluation (`--impure`) is enabled.
+      Fetch a file system tree or a plain file using one of the supported backends and return an attribute set with:
+
+      - the resulting fixed-output [store path](@docroot@/glossary.md#gloss-store-path)
+      - the corresponding [NAR](@docroot@/glossary.md#gloss-nar) hash
+      - backend-specific metadata (currently not documented). <!-- TODO: document output attributes -->
+
+      *input* must be an attribute set with the following attributes:
+
+      - `type` (String, required)
+
+        One of the [supported source types](#source-types).
+        This determines other required and allowed input attributes.
+
+      - `narHash` (String, optional)
+
+        The `narHash` parameter can be used to substitute the source of the tree.
+        It also allows for verification of tree contents that may not be provided by the underlying transfer mechanism.
+        If `narHash` is set, the source is first looked up is the Nix store and [substituters](@docroot@/command-ref/conf-file.md#conf-substituters), and only fetched if not available.
+
+      A subset of the output attributes of `fetchTree` can be re-used for subsequent calls to `fetchTree` to produce the same result again.
+      That is, `fetchTree` is idempotent.
+
+      Downloads are cached in `$XDG_CACHE_HOME/nix`.
+      The remote source will be fetched from the network if both are true:
+      - A NAR hash is supplied and the corresponding store path is not [valid](@docroot@/glossary.md#gloss-validity), that is, not available in the store
 
         > **Note**
         >
-      > The URL-like syntax requires the [`flakes` experimental feature](@docroot@/contributing/experimental-features.md#xp-feature-flakes) to be enabled.
+        > [Substituters](@docroot@/command-ref/conf-file.md#conf-substituters) are not used in fetching.
 
-      Here are some examples of how to use `fetchTree`:
+      - There is no cache entry or the cache entry is older than [`tarball-ttl`](@docroot@/command-ref/conf-file.md#conf-tarball-ttl)
 
-      - Fetch a GitHub repository using the attribute set representation:
+      ## Source types
 
-          ```nix
-          builtins.fetchTree {
-            type = "github";
-            owner = "NixOS";
-            repo = "nixpkgs";
-            rev = "ae2e6b3958682513d28f7d633734571fb18285dd";
-          }
-          ```
+      The following source types and associated input attributes are supported.
 
-        This evaluates to the following attribute set:
+      <!-- TODO: It would be soooo much more predictable to work with (and
+      document) if `fetchTree` was a curried call with the first paramter for
+      `type` or an attribute like `builtins.fetchTree.git`! -->
 
-          ```
-          {
-            lastModified = 1686503798;
-            lastModifiedDate = "20230611171638";
-            narHash = "sha256-rA9RqKP9OlBrgGCPvfd5HVAXDOy8k2SmPtB/ijShNXc=";
-            outPath = "/nix/store/l5m6qlvfs9sdw14ja3qbzpglcjlb6j1x-source";
-            rev = "ae2e6b3958682513d28f7d633734571fb18285dd";
-            shortRev = "ae2e6b3";
-          }
-          ```
+      - `"file"`
 
-      - Fetch the same GitHub repository using the URL-like syntax:
+        Place a plain file into the Nix store.
+        This is similar to [`builtins.fetchurl`](@docroot@/language/builtins.md#builtins-fetchurl)
 
-          ```
-          builtins.fetchTree "github:NixOS/nixpkgs/ae2e6b3958682513d28f7d633734571fb18285dd"
-          ```
+        - `url` (String, required)
+
+          Supported protocols:
+
+          - `https`
+
+            > **Example**
+            >
+            > ```nix
+            > fetchTree {
+            >   type = "file";
+            >   url = "https://example.com/index.html";
+            > }
+            > ```
+
+          - `http`
+
+            Insecure HTTP transfer for legacy sources.
+
+            > **Warning**
+            >
+            > HTTP performs no encryption or authentication.
+            > Use a `narHash` known in advance to ensure the output has expected contents.
+
+          - `file`
+
+            A file on the local file system.
+
+            > **Example**
+            >
+            > ```nix
+            > fetchTree {
+            >   type = "file";
+            >   url = "file:///home/eelco/nix/README.md";
+            > }
+            > ```
+
+      - `"tarball"`
+
+        Download a tar archive and extract it into the Nix store.
+        This has the same underyling implementation as [`builtins.fetchTarball`](@docroot@/language/builtins.md#builtins-fetchTarball)
+
+        - `url` (String, required)
+
+           > **Example**
+           >
+           > ```nix
+           > fetchTree {
+           >   type = "tarball";
+           >   url = "https://github.com/NixOS/nixpkgs/tarball/nixpkgs-23.11";
+           > }
+           > ```
+
+      - `"git"`
+
+        Fetch a Git tree and copy it to the Nix store.
+        This is similar to [`builtins.fetchGit`](@docroot@/language/builtins.md#builtins-fetchGit).
+
+        - `url` (String, required)
+
+          The URL formats supported are the same as for Git itself.
+
+          > **Example**
+          >
+          > ```nix
+          > fetchTree {
+          >   type = "git";
+          >   url = "git@github.com:NixOS/nixpkgs.git";
+          > }
+          > ```
+
+          > **Note**
+          >
+          > If the URL points to a local directory, and no `ref` or `rev` is given, Nix will only consider files added to the Git index, as listed by `git ls-files` but use the *current file contents* of the Git working directory.
+
+        - `ref` (String, optional)
+
+          A [Git reference](https://git-scm.com/book/en/v2/Git-Internals-Git-References), such as a branch or tag name.
+
+          Default: `"HEAD"`
+
+        - `rev` (String, optional)
+
+          A Git revision; a commit hash.
+
+          Default: the tip of `ref`
+
+        - `shallow` (Bool, optional)
+
+          Make a shallow clone when fetching the Git tree.
+
+          Default: `false`
+
+        - `submodules` (Bool, optional)
+
+          Also fetch submodules if available.
+
+          Default: `false`
+
+        - `allRefs` (Bool, optional)
+
+          If set to `true`, always fetch the entire repository, even if the latest commit is still in the cache.
+          Otherwise, only the latest commit is fetched if it is not already cached.
+
+          Default: `false`
+
+        - `lastModified` (Integer, optional)
+
+          Unix timestamp of the fetched commit.
+
+          If set, pass through the value to the output attribute set.
+          Otherwise, generated from the fetched Git tree.
+
+        - `revCount` (Integer, optional)
+
+          Number of revisions in the history of the Git repository before the fetched commit.
+
+          If set, pass through the value to the output attribute set.
+          Otherwise, generated from the fetched Git tree.
+
+      The following input types are still subject to change:
+
+      - `"path"`
+      - `"github"`
+      - `"gitlab"`
+      - `"sourcehut"`
+      - `"mercurial"`
+
+     *input* can also be a [URL-like reference](@docroot@/command-ref/new-cli/nix3-flake.md#flake-references).
+     The additional input types and the URL-like syntax requires the [`flakes` experimental feature](@docroot@/contributing/experimental-features.md#xp-feature-flakes) to be enabled.
+
+      > **Example**
+      >
+      > Fetch a GitHub repository using the attribute set representation:
+      >
+      > ```nix
+      > builtins.fetchTree {
+      >   type = "github";
+      >   owner = "NixOS";
+      >   repo = "nixpkgs";
+      >   rev = "ae2e6b3958682513d28f7d633734571fb18285dd";
+      > }
+      > ```
+      >
+      > This evaluates to the following attribute set:
+      >
+      > ```nix
+      > {
+      >   lastModified = 1686503798;
+      >   lastModifiedDate = "20230611171638";
+      >   narHash = "sha256-rA9RqKP9OlBrgGCPvfd5HVAXDOy8k2SmPtB/ijShNXc=";
+      >   outPath = "/nix/store/l5m6qlvfs9sdw14ja3qbzpglcjlb6j1x-source";
+      >   rev = "ae2e6b3958682513d28f7d633734571fb18285dd";
+      >   shortRev = "ae2e6b3";
+      > }
+      > ```
+
+      > **Example**
+      >
+      > Fetch the same GitHub repository using the URL-like syntax:
+      >
+      >   ```nix
+      >   builtins.fetchTree "github:NixOS/nixpkgs/ae2e6b3958682513d28f7d633734571fb18285dd"
+      >   ```
     )",
     .fun = prim_fetchTree,
     .experimentalFeature = Xp::FetchTree,
@@ -246,7 +416,7 @@ static void fetch(EvalState & state, const PosIdx pos, Value * * args, Value & v
             if (n == "url")
                 url = state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the url we should fetch");
             else if (n == "sha256")
-                expectedHash = newHashAllowEmpty(state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the sha256 of the content we should fetch"), htSHA256);
+                expectedHash = newHashAllowEmpty(state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the sha256 of the content we should fetch"), HashAlgorithm::SHA256);
             else if (n == "name")
                 name = state.forceStringNoCtx(*attr.value, attr.pos, "while evaluating the name of the content we should fetch");
             else
@@ -276,7 +446,7 @@ static void fetch(EvalState & state, const PosIdx pos, Value * * args, Value & v
         state.debugThrowLastTrace(EvalError("in pure evaluation mode, '%s' requires a 'sha256' argument", who));
 
     // early exit if pinned and already in the store
-    if (expectedHash && expectedHash->type == htSHA256) {
+    if (expectedHash && expectedHash->algo == HashAlgorithm::SHA256) {
         auto expectedPath = state.store->makeFixedOutputPath(
             name,
             FixedOutputInfo {
@@ -301,10 +471,10 @@ static void fetch(EvalState & state, const PosIdx pos, Value * * args, Value & v
     if (expectedHash) {
         auto hash = unpack
             ? state.store->queryPathInfo(storePath)->narHash
-            : hashFile(htSHA256, state.store->toRealPath(storePath));
+            : hashFile(HashAlgorithm::SHA256, state.store->toRealPath(storePath));
         if (hash != *expectedHash)
             state.debugThrowLastTrace(EvalError((unsigned int) 102, "hash mismatch in file downloaded from '%s':\n  specified: %s\n  got:       %s",
-                *url, expectedHash->to_string(HashFormat::Base32, true), hash.to_string(HashFormat::Base32, true)));
+                                                *url, expectedHash->to_string(HashFormat::Nix32, true), hash.to_string(HashFormat::Nix32, true)));
     }
 
     state.allowAndSetStorePathString(storePath, v);

src/libexpr/tests/local.mk

@@ -1,23 +0,0 @@
-check: libexpr-tests_RUN
-
-programs += libexpr-tests
-
-libexpr-tests_NAME := libnixexpr-tests
-
-libexpr-tests_DIR := $(d)
-
-ifeq ($(INSTALL_UNIT_TESTS), yes)
-  libexpr-tests_INSTALL_DIR := $(checkbindir)
-else
-  libexpr-tests_INSTALL_DIR :=
-endif
-
-libexpr-tests_SOURCES := \
-    $(wildcard $(d)/*.cc) \
-    $(wildcard $(d)/value/*.cc)
-
-libexpr-tests_CXXFLAGS += -I src/libexpr -I src/libutil -I src/libstore -I src/libexpr/tests -I src/libfetchers
-
-libexpr-tests_LIBS = libstore-tests libutils-tests libexpr libutil libstore libfetchers
-
-libexpr-tests_LDFLAGS := -lrapidcheck $(GTEST_LIBS) -lgmock

src/libexpr/value.hh

@@ -67,7 +67,6 @@ class Symbol;
 class PosIdx;
 struct Pos;
 class StorePath;
-class Store;
 class EvalState;
 class XMLWriter;
 
@@ -424,10 +423,9 @@ public:
     SourcePath path() const
     {
         assert(internalType == tPath);
-        return SourcePath {
-            .accessor = ref(_path.accessor->shared_from_this()),
-            .path = CanonPath(CanonPath::unchecked_t(), _path.path)
-        };
+        return SourcePath(
+            ref(_path.accessor->shared_from_this()),
+            CanonPath(CanonPath::unchecked_t(), _path.path));
     }
 
     std::string_view string_view() const

src/libfetchers/attrs.cc

@@ -106,7 +106,7 @@ std::map<std::string, std::string> attrsToQuery(const Attrs & attrs)
 
 Hash getRevAttr(const Attrs & attrs, const std::string & name)
 {
-    return Hash::parseAny(getStrAttr(attrs, name), htSHA1);
+    return Hash::parseAny(getStrAttr(attrs, name), HashAlgorithm::SHA1);
 }
 
 }

src/libfetchers/fetchers.cc

@@ -289,8 +289,8 @@ std::string Input::getType() const
 std::optional<Hash> Input::getNarHash() const
 {
     if (auto s = maybeGetStrAttr(attrs, "narHash")) {
-        auto hash = s->empty() ? Hash(htSHA256) : Hash::parseSRI(*s);
-        if (hash.type != htSHA256)
+        auto hash = s->empty() ? Hash(HashAlgorithm::SHA256) : Hash::parseSRI(*s);
+        if (hash.algo != HashAlgorithm::SHA256)
             throw UsageError("narHash must use SHA-256");
         return hash;
     }
@@ -314,7 +314,7 @@ std::optional<Hash> Input::getRev() const
         } catch (BadHash &e) {
             // Default to sha1 for backwards compatibility with existing
             // usages (e.g. `builtins.fetchTree` calls or flake inputs).
-            hash = Hash::parseAny(*s, htSHA1);
+            hash = Hash::parseAny(*s, HashAlgorithm::SHA1);
         }
     }
 
@@ -374,7 +374,7 @@ void InputScheme::clone(const Input & input, const Path & destDir) const
 std::pair<StorePath, Input> InputScheme::fetch(ref<Store> store, const Input & input)
 {
     auto [accessor, input2] = getAccessor(store, input);
-    auto storePath = accessor->root().fetchToStore(store, input2.getName());
+    auto storePath = SourcePath(accessor).fetchToStore(store, input2.getName());
     return {storePath, input2};
 }
 

src/libfetchers/filtering-input-accessor.cc

@@ -0,0 +1,83 @@
+#include "filtering-input-accessor.hh"
+
+namespace nix {
+
+std::string FilteringInputAccessor::readFile(const CanonPath & path)
+{
+    checkAccess(path);
+    return next->readFile(prefix + path);
+}
+
+bool FilteringInputAccessor::pathExists(const CanonPath & path)
+{
+    return isAllowed(path) && next->pathExists(prefix + path);
+}
+
+std::optional<InputAccessor::Stat> FilteringInputAccessor::maybeLstat(const CanonPath & path)
+{
+    checkAccess(path);
+    return next->maybeLstat(prefix + path);
+}
+
+InputAccessor::DirEntries FilteringInputAccessor::readDirectory(const CanonPath & path)
+{
+    checkAccess(path);
+    DirEntries entries;
+    for (auto & entry : next->readDirectory(prefix + path)) {
+        if (isAllowed(path + entry.first))
+            entries.insert(std::move(entry));
+    }
+    return entries;
+}
+
+std::string FilteringInputAccessor::readLink(const CanonPath & path)
+{
+    checkAccess(path);
+    return next->readLink(prefix + path);
+}
+
+std::string FilteringInputAccessor::showPath(const CanonPath & path)
+{
+    return next->showPath(prefix + path);
+}
+
+void FilteringInputAccessor::checkAccess(const CanonPath & path)
+{
+    if (!isAllowed(path))
+        throw makeNotAllowedError
+            ? makeNotAllowedError(path)
+            : RestrictedPathError("access to path '%s' is forbidden", showPath(path));
+}
+
+struct AllowListInputAccessorImpl : AllowListInputAccessor
+{
+    std::set<CanonPath> allowedPaths;
+
+    AllowListInputAccessorImpl(
+        ref<InputAccessor> next,
+        std::set<CanonPath> && allowedPaths,
+        MakeNotAllowedError && makeNotAllowedError)
+        : AllowListInputAccessor(SourcePath(next), std::move(makeNotAllowedError))
+        , allowedPaths(std::move(allowedPaths))
+    { }
+
+    bool isAllowed(const CanonPath & path) override
+    {
+        return path.isAllowed(allowedPaths);
+    }
+
+    void allowPath(CanonPath path) override
+    {
+        allowedPaths.insert(std::move(path));
+    }
+};
+
+ref<AllowListInputAccessor> AllowListInputAccessor::create(
+    ref<InputAccessor> next,
+    std::set<CanonPath> && allowedPaths,
+    MakeNotAllowedError && makeNotAllowedError)
+{
+    return make_ref<AllowListInputAccessorImpl>(next, std::move(allowedPaths), std::move(makeNotAllowedError));
+}
+
+}

src/libfetchers/filtering-input-accessor.hh

@@ -0,0 +1,73 @@
+#pragma once
+
+#include "input-accessor.hh"
+
+namespace nix {
+
+/**
+ * A function that should throw an exception of type
+ * `RestrictedPathError` explaining that access to `path` is
+ * forbidden.
+ */
+typedef std::function<RestrictedPathError(const CanonPath & path)> MakeNotAllowedError;
+
+/**
+ * An abstract wrapping `InputAccessor` that performs access
+ * control. Subclasses should override `isAllowed()` to implement an
+ * access control policy. The error message is customized at construction.
+ */
+struct FilteringInputAccessor : InputAccessor
+{
+    ref<InputAccessor> next;
+    CanonPath prefix;
+    MakeNotAllowedError makeNotAllowedError;
+
+    FilteringInputAccessor(const SourcePath & src, MakeNotAllowedError && makeNotAllowedError)
+        : next(src.accessor)
+        , prefix(src.path)
+        , makeNotAllowedError(std::move(makeNotAllowedError))
+    { }
+
+    std::string readFile(const CanonPath & path) override;
+
+    bool pathExists(const CanonPath & path) override;
+
+    std::optional<Stat> maybeLstat(const CanonPath & path) override;
+
+    DirEntries readDirectory(const CanonPath & path) override;
+
+    std::string readLink(const CanonPath & path) override;
+
+    std::string showPath(const CanonPath & path) override;
+
+    /**
+     * Call `makeNotAllowedError` to throw a `RestrictedPathError`
+     * exception if `isAllowed()` returns `false` for `path`.
+     */
+    void checkAccess(const CanonPath & path);
+
+    /**
+     * Return `true` iff access to path is allowed.
+     */
+    virtual bool isAllowed(const CanonPath & path) = 0;
+};
+
+/**
+ * A wrapping `InputAccessor` that checks paths against an allow-list.
+ */
+struct AllowListInputAccessor : public FilteringInputAccessor
+{
+    /**
+     * Grant access to the specified path.
+     */
+    virtual void allowPath(CanonPath path) = 0;
+
+    static ref<AllowListInputAccessor> create(
+        ref<InputAccessor> next,
+        std::set<CanonPath> && allowedPaths,
+        MakeNotAllowedError && makeNotAllowedError);
+
+    using FilteringInputAccessor::FilteringInputAccessor;
+};
+
+}

src/libfetchers/fs-input-accessor.cc

@@ -4,19 +4,12 @@
 
 namespace nix {
 
-struct FSInputAccessorImpl : FSInputAccessor, PosixSourceAccessor
+struct FSInputAccessor : InputAccessor, PosixSourceAccessor
 {
     CanonPath root;
-    std::optional<std::set<CanonPath>> allowedPaths;
-    MakeNotAllowedError makeNotAllowedError;
 
-    FSInputAccessorImpl(
-        const CanonPath & root,
-        std::optional<std::set<CanonPath>> && allowedPaths,
-        MakeNotAllowedError && makeNotAllowedError)
+    FSInputAccessor(const CanonPath & root)
         : root(root)
-        , allowedPaths(std::move(allowedPaths))
-        , makeNotAllowedError(std::move(makeNotAllowedError))
     {
         displayPrefix = root.isRoot() ? "" : root.abs();
     }
@@ -27,39 +20,30 @@ struct FSInputAccessorImpl : FSInputAccessor, PosixSourceAccessor
         std::function<void(uint64_t)> sizeCallback) override
     {
         auto absPath = makeAbsPath(path);
-        checkAllowed(absPath);
         PosixSourceAccessor::readFile(absPath, sink, sizeCallback);
     }
 
     bool pathExists(const CanonPath & path) override
     {
-        auto absPath = makeAbsPath(path);
-        return isAllowed(absPath) && PosixSourceAccessor::pathExists(absPath);
+        return PosixSourceAccessor::pathExists(makeAbsPath(path));
     }
 
     std::optional<Stat> maybeLstat(const CanonPath & path) override
     {
-        auto absPath = makeAbsPath(path);
-        checkAllowed(absPath);
-        return PosixSourceAccessor::maybeLstat(absPath);
+        return PosixSourceAccessor::maybeLstat(makeAbsPath(path));
     }
 
     DirEntries readDirectory(const CanonPath & path) override
     {
-        auto absPath = makeAbsPath(path);
-        checkAllowed(absPath);
         DirEntries res;
-        for (auto & entry : PosixSourceAccessor::readDirectory(absPath))
-            if (isAllowed(absPath + entry.first))
+        for (auto & entry : PosixSourceAccessor::readDirectory(makeAbsPath(path)))
             res.emplace(entry);
         return res;
     }
 
     std::string readLink(const CanonPath & path) override
     {
-        auto absPath = makeAbsPath(path);
-        checkAllowed(absPath);
-        return PosixSourceAccessor::readLink(absPath);
+        return PosixSourceAccessor::readLink(makeAbsPath(path));
     }
 
     CanonPath makeAbsPath(const CanonPath & path)
@@ -67,59 +51,22 @@ struct FSInputAccessorImpl : FSInputAccessor, PosixSourceAccessor
         return root + path;
     }
 
-    void checkAllowed(const CanonPath & absPath) override
-    {
-        if (!isAllowed(absPath))
-            throw makeNotAllowedError
-                ? makeNotAllowedError(absPath)
-                : RestrictedPathError("access to path '%s' is forbidden", absPath);
-    }
-
-    bool isAllowed(const CanonPath & absPath)
-    {
-        if (!absPath.isWithin(root))
-            return false;
-
-        if (allowedPaths) {
-            auto p = absPath.removePrefix(root);
-            if (!p.isAllowed(*allowedPaths))
-                return false;
-        }
-
-        return true;
-    }
-
-    void allowPath(CanonPath path) override
-    {
-        if (allowedPaths)
-            allowedPaths->insert(std::move(path));
-    }
-
-    bool hasAccessControl() override
-    {
-        return (bool) allowedPaths;
-    }
-
     std::optional<CanonPath> getPhysicalPath(const CanonPath & path) override
     {
         return makeAbsPath(path);
     }
 };
 
-ref<FSInputAccessor> makeFSInputAccessor(
-    const CanonPath & root,
-    std::optional<std::set<CanonPath>> && allowedPaths,
-    MakeNotAllowedError && makeNotAllowedError)
+ref<InputAccessor> makeFSInputAccessor(const CanonPath & root)
 {
-    return make_ref<FSInputAccessorImpl>(root, std::move(allowedPaths), std::move(makeNotAllowedError));
+    return make_ref<FSInputAccessor>(root);
 }
 
-ref<FSInputAccessor> makeStorePathAccessor(
+ref<InputAccessor> makeStorePathAccessor(
     ref<Store> store,
-    const StorePath & storePath,
-    MakeNotAllowedError && makeNotAllowedError)
+    const StorePath & storePath)
 {
-    return makeFSInputAccessor(CanonPath(store->toRealPath(storePath)), {}, std::move(makeNotAllowedError));
+    return makeFSInputAccessor(CanonPath(store->toRealPath(storePath)));
 }
 
 SourcePath getUnfilteredRootPath(CanonPath path)

src/libfetchers/fs-input-accessor.hh

@@ -7,26 +7,12 @@ namespace nix {
 class StorePath;
 class Store;
 
-struct FSInputAccessor : InputAccessor
-{
-    virtual void checkAllowed(const CanonPath & absPath) = 0;
+ref<InputAccessor> makeFSInputAccessor(
+    const CanonPath & root);
 
-    virtual void allowPath(CanonPath path) = 0;
-
-    virtual bool hasAccessControl() = 0;
-};
-
-typedef std::function<RestrictedPathError(const CanonPath & path)> MakeNotAllowedError;
-
-ref<FSInputAccessor> makeFSInputAccessor(
-    const CanonPath & root,
-    std::optional<std::set<CanonPath>> && allowedPaths = {},
-    MakeNotAllowedError && makeNotAllowedError = {});
-
-ref<FSInputAccessor> makeStorePathAccessor(
+ref<InputAccessor> makeStorePathAccessor(
     ref<Store> store,
-    const StorePath & storePath,
-    MakeNotAllowedError && makeNotAllowedError = {});
+    const StorePath & storePath);
 
 SourcePath getUnfilteredRootPath(CanonPath path);
 

src/libfetchers/git-utils.cc

@@ -94,7 +94,7 @@ Hash toHash(const git_oid & oid)
     #ifdef GIT_EXPERIMENTAL_SHA256
     assert(oid.type == GIT_OID_SHA1);
     #endif
-    Hash hash(htSHA1);
+    Hash hash(HashAlgorithm::SHA1);
     memcpy(hash.hash, oid.id, hash.hashSize);
     return hash;
 }
@@ -594,7 +594,7 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
         std::string re = R"(Good "git" signature for \* with .* key SHA256:[)";
         for (const fetchers::PublicKey & k : publicKeys){
             // Calculate sha256 fingerprint from public key and escape the regex symbol '+' to match the key literally
-            auto fingerprint = trim(hashString(htSHA256, base64Decode(k.key)).to_string(nix::HashFormat::Base64, false), "=");
+            auto fingerprint = trim(hashString(HashAlgorithm::SHA256, base64Decode(k.key)).to_string(nix::HashFormat::Base64, false), "=");
             auto escaped_fingerprint = std::regex_replace(fingerprint, std::regex("\\+"), "\\+" );
             re += "(" + escaped_fingerprint + ")";
         }
@@ -612,7 +612,7 @@ struct GitRepoImpl : GitRepo, std::enable_shared_from_this<GitRepoImpl>
         fetchers::Attrs cacheKey({{"_what", "treeHashToNarHash"}, {"treeHash", treeHash.gitRev()}});
 
         if (auto res = fetchers::getCache()->lookup(cacheKey))
-            return Hash::parseAny(fetchers::getStrAttr(*res, "narHash"), htSHA256);
+            return Hash::parseAny(fetchers::getStrAttr(*res, "narHash"), HashAlgorithm::SHA256);
 
         auto narHash = accessor->hashPath(CanonPath::root);
 
@@ -725,7 +725,7 @@ struct GitInputAccessor : InputAccessor
         return toHash(*git_tree_entry_id(entry));
     }
 
-    std::map<CanonPath, TreeEntry> lookupCache;
+    std::unordered_map<CanonPath, TreeEntry> lookupCache;
 
     /* Recursively look up 'path' relative to the root. */
     git_tree_entry * lookup(const CanonPath & path)

src/libfetchers/git.cc

@@ -9,6 +9,7 @@
 #include "processes.hh"
 #include "git.hh"
 #include "fs-input-accessor.hh"
+#include "filtering-input-accessor.hh"
 #include "mounted-input-accessor.hh"
 #include "git-utils.hh"
 #include "logging.hh"
@@ -52,7 +53,7 @@ bool touchCacheFile(const Path & path, time_t touch_time)
 Path getCachePath(std::string_view key)
 {
     return getCacheDir() + "/nix/gitv3/" +
-        hashString(htSHA256, key).to_string(HashFormat::Base32, false);
+        hashString(HashAlgorithm::SHA256, key).to_string(HashFormat::Nix32, false);
 }
 
 // Returns the name of the HEAD branch.
@@ -369,7 +370,7 @@ struct GitInputScheme : InputScheme
     {
         auto checkHashType = [&](const std::optional<Hash> & hash)
         {
-            if (hash.has_value() && !(hash->type == htSHA1 || hash->type == htSHA256))
+            if (hash.has_value() && !(hash->algo == HashAlgorithm::SHA1 || hash->algo == HashAlgorithm::SHA256))
                 throw Error("Hash '%s' is not supported by Git. Supported types are sha1 and sha256.", hash->to_string(HashFormat::Base16, true));
         };
 
@@ -559,7 +560,7 @@ struct GitInputScheme : InputScheme
                         repoInfo.url
                         );
             } else
-                input.attrs.insert_or_assign("rev", Hash::parseAny(chomp(readFile(localRefFile)), htSHA1).gitRev());
+                input.attrs.insert_or_assign("rev", Hash::parseAny(chomp(readFile(localRefFile)), HashAlgorithm::SHA1).gitRev());
 
             // cache dir lock is removed at scope end; we will only use read-only operations on specific revisions in the remainder
         }
@@ -639,7 +640,10 @@ struct GitInputScheme : InputScheme
                 repoInfo.workdirInfo.files.insert(submodule.path);
 
         ref<InputAccessor> accessor =
-            makeFSInputAccessor(CanonPath(repoInfo.url), repoInfo.workdirInfo.files, makeNotAllowedError(repoInfo.url));
+            AllowListInputAccessor::create(
+                makeFSInputAccessor(CanonPath(repoInfo.url)),
+                std::move(repoInfo.workdirInfo.files),
+                makeNotAllowedError(repoInfo.url));
 
         /* If the repo has submodules, return a mounted input accessor
            consisting of the accessor for the top-level repo and the

src/libfetchers/github.cc

@@ -43,7 +43,7 @@ struct GitArchiveInputScheme : InputScheme
         auto size = path.size();
         if (size == 3) {
             if (std::regex_match(path[2], revRegex))
-                rev = Hash::parseAny(path[2], htSHA1);
+                rev = Hash::parseAny(path[2], HashAlgorithm::SHA1);
             else if (std::regex_match(path[2], refRegex))
                 ref = path[2];
             else
@@ -69,7 +69,7 @@ struct GitArchiveInputScheme : InputScheme
             if (name == "rev") {
                 if (rev)
                     throw BadURL("URL '%s' contains multiple commit hashes", url.url);
-                rev = Hash::parseAny(value, htSHA1);
+                rev = Hash::parseAny(value, HashAlgorithm::SHA1);
             }
             else if (name == "ref") {
                 if (!std::regex_match(value, refRegex))
@@ -323,9 +323,10 @@ struct GitHubInputScheme : GitArchiveInputScheme
             readFile(
                 store->toRealPath(
                     downloadFile(store, url, "source", false, headers).storePath)));
+
         return RefInfo {
-            .rev = Hash::parseAny(std::string { json["sha"] }, htSHA1),
-            .treeHash = Hash::parseAny(std::string { json["commit"]["tree"]["sha"] }, htSHA1)
+            .rev = Hash::parseAny(std::string { json["sha"] }, HashAlgorithm::SHA1),
+            .treeHash = Hash::parseAny(std::string { json["commit"]["tree"]["sha"] }, HashAlgorithm::SHA1)
         };
     }
 
@@ -396,8 +397,9 @@ struct GitLabInputScheme : GitArchiveInputScheme
             readFile(
                 store->toRealPath(
                     downloadFile(store, url, "source", false, headers).storePath)));
+
         return RefInfo {
-            .rev = Hash::parseAny(std::string(json[0]["id"]), htSHA1)
+            .rev = Hash::parseAny(std::string(json[0]["id"]), HashAlgorithm::SHA1)
         };
     }
 
@@ -489,7 +491,7 @@ struct SourceHutInputScheme : GitArchiveInputScheme
             throw BadURL("in '%d', couldn't find ref '%d'", input.to_string(), ref);
 
         return RefInfo {
-            .rev = Hash::parseAny(*id, htSHA1)
+            .rev = Hash::parseAny(*id, HashAlgorithm::SHA1)
         };
     }
 

src/libfetchers/indirect.cc

@@ -20,7 +20,7 @@ struct IndirectInputScheme : InputScheme
         if (path.size() == 1) {
         } else if (path.size() == 2) {
             if (std::regex_match(path[1], revRegex))
-                rev = Hash::parseAny(path[1], htSHA1);
+                rev = Hash::parseAny(path[1], HashAlgorithm::SHA1);
             else if (std::regex_match(path[1], refRegex))
                 ref = path[1];
             else
@@ -31,7 +31,7 @@ struct IndirectInputScheme : InputScheme
             ref = path[1];
             if (!std::regex_match(path[2], revRegex))
                 throw BadURL("in flake URL '%s', '%s' is not a commit hash", url.url, path[2]);
-            rev = Hash::parseAny(path[2], htSHA1);
+            rev = Hash::parseAny(path[2], HashAlgorithm::SHA1);
         } else
             throw BadURL("GitHub URL '%s' is invalid", url.url);
 

src/libfetchers/input-accessor.cc

@@ -44,8 +44,8 @@ StorePath InputAccessor::fetchToStore(
 
     auto storePath =
         settings.readOnlyMode
-        ? store->computeStorePathFromDump(*source, name, method, htSHA256).first
-        : store->addToStoreFromDump(*source, name, method, htSHA256, repair);
+        ? store->computeStorePathFromDump(*source, name, method, HashAlgorithm::SHA256).first
+        : store->addToStoreFromDump(*source, name, method, HashAlgorithm::SHA256, repair);
 
     if (cacheKey)
         fetchers::getCache()->add(store, *cacheKey, {}, storePath, true);
@@ -53,11 +53,6 @@ StorePath InputAccessor::fetchToStore(
     return storePath;
 }
 
-SourcePath InputAccessor::root()
-{
-    return {ref(shared_from_this()), CanonPath::root};
-}
-
 std::ostream & operator << (std::ostream & str, const SourcePath & path)
 {
     str << path.to_string();
@@ -88,7 +83,7 @@ SourcePath SourcePath::parent() const
 
 SourcePath SourcePath::resolveSymlinks() const
 {
-    auto res = accessor->root();
+    auto res = SourcePath(accessor);
 
     int linksAllowed = 1024;
 

src/libfetchers/input-accessor.hh

@@ -36,8 +36,6 @@ struct InputAccessor : virtual SourceAccessor, std::enable_shared_from_this<Inpu
         FileIngestionMethod method = FileIngestionMethod::Recursive,
         PathFilter * filter = nullptr,
         RepairFlag repair = NoRepair);
-
-    SourcePath root();
 };
 
 /**
@@ -51,6 +49,11 @@ struct SourcePath
     ref<InputAccessor> accessor;
     CanonPath path;
 
+    SourcePath(ref<InputAccessor> accessor, CanonPath path = CanonPath::root)
+        : accessor(std::move(accessor))
+        , path(std::move(path))
+    { }
+
     std::string_view baseName() const;
 
     /**
@@ -127,7 +130,7 @@ struct SourcePath
     { return accessor->getPhysicalPath(path); }
 
     std::string to_string() const
-    { return path.abs(); }
+    { return accessor->showPath(path); }
 
     /**
      * Append a `CanonPath` to this path.

src/libfetchers/mercurial.cc

@@ -210,7 +210,7 @@ struct MercurialInputScheme : InputScheme
                     return files.count(file);
                 };
 
-                auto storePath = store->addToStore(input.getName(), actualPath, FileIngestionMethod::Recursive, htSHA256, filter);
+                auto storePath = store->addToStore(input.getName(), actualPath, FileIngestionMethod::Recursive, HashAlgorithm::SHA256, filter);
 
                 return {std::move(storePath), input};
             }
@@ -220,7 +220,7 @@ struct MercurialInputScheme : InputScheme
 
         auto checkHashType = [&](const std::optional<Hash> & hash)
         {
-            if (hash.has_value() && hash->type != htSHA1)
+            if (hash.has_value() && hash->algo != HashAlgorithm::SHA1)
                 throw Error("Hash '%s' is not supported by Mercurial. Only sha1 is supported.", hash->to_string(HashFormat::Base16, true));
         };
 
@@ -260,14 +260,14 @@ struct MercurialInputScheme : InputScheme
         });
 
         if (auto res = getCache()->lookup(store, unlockedAttrs)) {
-            auto rev2 = Hash::parseAny(getStrAttr(res->first, "rev"), htSHA1);
+            auto rev2 = Hash::parseAny(getStrAttr(res->first, "rev"), HashAlgorithm::SHA1);
             if (!input.getRev() || input.getRev() == rev2) {
                 input.attrs.insert_or_assign("rev", rev2.gitRev());
                 return makeResult(res->first, std::move(res->second));
             }
         }
 
-        Path cacheDir = fmt("%s/nix/hg/%s", getCacheDir(), hashString(htSHA256, actualUrl).to_string(HashFormat::Base32, false));
+        Path cacheDir = fmt("%s/nix/hg/%s", getCacheDir(), hashString(HashAlgorithm::SHA256, actualUrl).to_string(HashFormat::Nix32, false));
 
         /* If this is a commit hash that we already have, we don't
            have to pull again. */
@@ -301,7 +301,7 @@ struct MercurialInputScheme : InputScheme
             runHg({ "log", "-R", cacheDir, "-r", revOrRef, "--template", "{node} {rev} {branch}" }));
         assert(tokens.size() == 3);
 
-        input.attrs.insert_or_assign("rev", Hash::parseAny(tokens[0], htSHA1).gitRev());
+        input.attrs.insert_or_assign("rev", Hash::parseAny(tokens[0], HashAlgorithm::SHA1).gitRev());
         auto revCount = std::stoull(tokens[1]);
         input.attrs.insert_or_assign("ref", tokens[2]);
 

src/libfetchers/tarball.cc

@@ -73,7 +73,7 @@ DownloadFileResult downloadFile(
     } else {
         StringSink sink;
         dumpString(res.data, sink);
-        auto hash = hashString(htSHA256, res.data);
+        auto hash = hashString(HashAlgorithm::SHA256, res.data);
         ValidPathInfo info {
             *store,
             name,
@@ -82,7 +82,7 @@ DownloadFileResult downloadFile(
                 .hash = hash,
                 .references = {},
             },
-            hashString(htSHA256, sink.s),
+            hashString(HashAlgorithm::SHA256, sink.s),
         };
         info.narSize = sink.s.size();
         auto source = StringSource { sink.s };
@@ -156,7 +156,7 @@ DownloadTarballResult downloadTarball(
             throw nix::Error("tarball '%s' contains an unexpected number of top-level files", url);
         auto topDir = tmpDir + "/" + members.begin()->name;
         lastModified = lstat(topDir).st_mtime;
-        unpackedStorePath = store->addToStore(name, topDir, FileIngestionMethod::Recursive, htSHA256, defaultPathFilter, NoRepair);
+        unpackedStorePath = store->addToStore(name, topDir, FileIngestionMethod::Recursive, HashAlgorithm::SHA256, defaultPathFilter, NoRepair);
     }
 
     Attrs infoAttrs({

src/libmain/local.mk

@@ -14,4 +14,4 @@ libmain_LIBS = libstore libutil
 
 libmain_ALLOW_UNDEFINED = 1
 
-$(eval $(call install-file-in, $(d)/nix-main.pc, $(libdir)/pkgconfig, 0644))
+$(eval $(call install-file-in, $(buildprefix)$(d)/nix-main.pc, $(libdir)/pkgconfig, 0644))