Merge pull request #29 from DeterminateSystems/stable-flakes

Make the flakes experimental feature stable

.github/workflows/ci.yml

@@ -23,7 +23,7 @@ jobs:
         with:
           flakehub: true
       - uses: DeterminateSystems/magic-nix-cache-action@main
-      - run: nix --experimental-features 'nix-command flakes' flake check -L
+      - run: nix flake check -L
 
   vm_tests:
     needs: tests

doc/manual/src/contributing/hacking.md

@@ -14,10 +14,9 @@ The following instructions assume you already have some version of Nix installed
 
 ## Building Nix with flakes
 
-This section assumes you are using Nix with the [`flakes`] and [`nix-command`] experimental features enabled.
+This section assumes you are using Nix with the experimental feature [`nix-command`] enabled.
 See the [Building Nix](#building-nix) section for equivalent instructions using stable Nix interfaces.
 
-[`flakes`]: @docroot@/contributing/experimental-features.md#xp-feature-flakes
 [`nix-command`]: @docroot@/contributing/experimental-features.md#xp-nix-command
 
 To build all dependencies and start a shell in which all environment variables are set up so that those dependencies can be found:

src/libcmd/common-eval-args.cc

@@ -22,7 +22,6 @@ EvalSettings evalSettings {
         {
             "flake",
             [](ref<Store> store, std::string_view rest) {
-                experimentalFeatureSettings.require(Xp::Flakes);
                 // FIXME `parseFlakeRef` should take a `std::string_view`.
                 auto flakeRef = parseFlakeRef(std::string { rest }, {}, true, false);
                 debug("fetching flake search path element '%s''", rest);
@@ -229,7 +228,6 @@ SourcePath lookupFileArg(EvalState & state, std::string_view s, const Path * bas
     }
 
     else if (hasPrefix(s, "flake:")) {
-        experimentalFeatureSettings.require(Xp::Flakes);
         auto flakeRef = parseFlakeRef(std::string(s.substr(6)), {}, true, false);
         auto storePath = flakeRef.resolve(state.store).fetchTree(state.store).first;
         return state.rootPath(CanonPath(state.store->toRealPath(storePath)));

src/libcmd/installables.cc

@@ -394,9 +394,6 @@ void completeFlakeRefWithFragment(
 
 void completeFlakeRef(AddCompletions & completions, ref<Store> store, std::string_view prefix)
 {
-    if (!experimentalFeatureSettings.isEnabled(Xp::Flakes))
-        return;
-
     if (prefix == "")
         completions.add(".");
 

src/libexpr/primops/fetchTree.cc

@@ -163,15 +163,11 @@ static void fetchTree(
             }
             input = fetchers::Input::fromAttrs(std::move(attrs));
         } else {
-            if (!experimentalFeatureSettings.isEnabled(Xp::Flakes))
-                state.error<EvalError>(
-                    "passing a string argument to 'fetchTree' requires the 'flakes' experimental feature"
-                ).atPos(pos).debugThrow();
             input = fetchers::Input::fromURL(url);
         }
     }
 
-    if (!state.settings.pureEval && !input.isDirect() && experimentalFeatureSettings.isEnabled(Xp::Flakes))
+    if (!state.settings.pureEval && !input.isDirect())
         input = lookupInRegistries(state.store, input).first;
 
     if (state.settings.pureEval && !input.isLocked()) {
@@ -383,7 +379,6 @@ static RegisterPrimOp primop_fetchTree({
       - `"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**
       >
@@ -420,7 +415,6 @@ static RegisterPrimOp primop_fetchTree({
       >   ```
     )",
     .fun = prim_fetchTree,
-    .experimentalFeature = Xp::FetchTree,
 });
 
 static void fetch(EvalState & state, const PosIdx pos, Value * * args, Value & v,

src/libfetchers/github.cc

@@ -299,11 +299,6 @@ struct GitArchiveInputScheme : InputScheme
                 input.getNarHash().has_value());
     }
 
-    std::optional<ExperimentalFeature> experimentalFeature() const override
-    {
-        return Xp::Flakes;
-    }
-
     std::optional<std::string> getFingerprint(ref<Store> store, const Input & input) const override
     {
         if (auto rev = input.getRev())

src/libfetchers/indirect.cc

@@ -102,11 +102,6 @@ struct IndirectInputScheme : InputScheme
         throw Error("indirect input '%s' cannot be fetched directly", input.to_string());
     }
 
-    std::optional<ExperimentalFeature> experimentalFeature() const override
-    {
-        return Xp::Flakes;
-    }
-
     bool isDirect(const Input & input) const override
     { return false; }
 };

src/libfetchers/path.cc

@@ -174,11 +174,6 @@ struct PathInputScheme : InputScheme
             return std::nullopt;
         }
     }
-
-    std::optional<ExperimentalFeature> experimentalFeature() const override
-    {
-        return Xp::Flakes;
-    }
 };
 
 static auto rPathInputScheme = OnStartup([] { registerInputScheme(std::make_unique<PathInputScheme>()); });

src/libfetchers/registry.cc

@@ -156,7 +156,7 @@ struct RegistrySettings : Config
 
           When empty, disables the global flake registry.
         )",
-        {}, true, Xp::Flakes};
+        {}, true};
 };
 
 RegistrySettings registrySettings;

src/libflake/flake-settings.hh

@@ -17,13 +17,7 @@ struct FlakeSettings : public Config
     FlakeSettings();
 
     Setting<bool> useRegistries{
-        this,
+        this, true, "use-registries", "Whether to use flake registries to resolve flake references.", {}, true};
-        true,
-        "use-registries",
-        "Whether to use flake registries to resolve flake references.",
-        {},
-        true,
-        Xp::Flakes};
 
     Setting<bool> acceptFlakeConfig{
         this,
@@ -31,8 +25,7 @@ struct FlakeSettings : public Config
         "accept-flake-config",
         "Whether to accept nix configuration from a flake without prompting.",
         {},
-        true,
+        true};
-        Xp::Flakes};
 
     Setting<std::string> commitLockFileSummary{
         this,
@@ -43,8 +36,7 @@ struct FlakeSettings : public Config
           empty, the summary is generated based on the action performed.
         )",
         {"commit-lockfile-summary"},
-        true,
+        true};
-        Xp::Flakes};
 };
 
 // TODO: don't use a global variable.

src/libflake/flake/flake.cc

@@ -343,8 +343,6 @@ LockedFlake lockFlake(
     const FlakeRef & topRef,
     const LockFlags & lockFlags)
 {
-    experimentalFeatureSettings.require(Xp::Flakes);
-
     FlakeCache flakeCache;
 
     auto useRegistries = lockFlags.useRegistries.value_or(flakeSettings.useRegistries);
@@ -744,8 +742,6 @@ void callFlake(EvalState & state,
     const LockedFlake & lockedFlake,
     Value & vRes)
 {
-    experimentalFeatureSettings.require(Xp::Flakes);
-
     auto [lockFileStr, keyMap] = lockedFlake.lockFile.to_string();
 
     auto overrides = state.buildBindings(lockedFlake.nodePaths.size());
@@ -837,7 +833,6 @@ static RegisterPrimOp r2({
       ```
     )",
     .fun = prim_getFlake,
-    .experimentalFeature = Xp::Flakes,
 });
 
 static void prim_parseFlakeRef(
@@ -881,7 +876,6 @@ static RegisterPrimOp r3({
       ```
     )",
     .fun = prim_parseFlakeRef,
-    .experimentalFeature = Xp::Flakes,
 });
 
 
@@ -938,7 +932,6 @@ static RegisterPrimOp r4({
       ```
     )",
     .fun = prim_flakeRefToString,
-    .experimentalFeature = Xp::Flakes,
 });
 
 }

src/libutil/config.cc

@@ -341,11 +341,11 @@ template<> std::set<ExperimentalFeature> BaseSetting<std::set<ExperimentalFeatur
 {
     std::set<ExperimentalFeature> res;
     for (auto & s : tokenizeString<StringSet>(str)) {
-        if (auto thisXpFeature = parseExperimentalFeature(s); thisXpFeature) {
+        if (auto thisXpFeature = parseExperimentalFeature(s))
             res.insert(thisXpFeature.value());
-            if (thisXpFeature.value() == Xp::Flakes)
+        else if (stabilizedFeatures.count(s))
-                res.insert(Xp::FetchTree);
+            debug("experimental feature '%s' is now stable", s);
-        } else
+        else
             warn("unknown experimental feature '%s'", s);
     }
     return res;

src/libutil/config.hh

@@ -386,7 +386,7 @@ struct ExperimentalFeatureSettings : Config {
           Example:
 
           ```
-          experimental-features = nix-command flakes
+          experimental-features = nix-command
           ```
 
           The following experimental features are available:

src/libutil/experimental-features.cc

@@ -70,19 +70,12 @@ constexpr std::array<ExperimentalFeatureDetails, numXpFeatures> xpFeatureDetails
         )",
         .trackingUrl = "https://github.com/NixOS/nix/milestone/42",
     },
-    {
-        .tag = Xp::Flakes,
-        .name = "flakes",
-        .description = R"(
-            Enable flakes. See the manual entry for [`nix
-            flake`](@docroot@/command-ref/new-cli/nix3-flake.md) for details.
-        )",
-        .trackingUrl = "https://github.com/NixOS/nix/milestone/27",
-    },
     {
         .tag = Xp::FetchTree,
         .name = "fetch-tree",
         .description = R"(
+            *Enabled for Determinate Nix Installer users since 2.24*
+
             Enable the use of the [`fetchTree`](@docroot@/language/builtins.md#builtins-fetchTree) built-in function in the Nix language.
 
             `fetchTree` exposes a generic interface for fetching remote file system trees from different types of remote sources.
@@ -299,12 +292,18 @@ constexpr std::array<ExperimentalFeatureDetails, numXpFeatures> xpFeatureDetails
 static_assert(
     []() constexpr {
         for (auto [index, feature] : enumerate(xpFeatureDetails))
-            if (index != (size_t)feature.tag)
+            if (index != (size_t) feature.tag)
                 return false;
         return true;
     }(),
     "array order does not match enum tag order");
 
+/**
+ * A set of previously experimental features that are now considered
+ * stable. We don't warn if users have these in `experimental-features`.
+ */
+std::set<std::string> stabilizedFeatures{"flakes"};
+
 const std::optional<ExperimentalFeature> parseExperimentalFeature(const std::string_view & name)
 {
     using ReverseXpMap = std::map<std::string_view, ExperimentalFeature>;

src/libutil/experimental-features.hh

@@ -19,7 +19,6 @@ enum struct ExperimentalFeature
 {
     CaDerivations,
     ImpureDerivations,
-    Flakes,
     FetchTree,
     NixCommand,
     GitHashing,
@@ -38,6 +37,8 @@ enum struct ExperimentalFeature
     VerifiedFetches,
 };
 
+extern std::set<std::string> stabilizedFeatures;
+
 /**
  * Just because writing `ExperimentalFeature::CaDerivations` is way too long
  */

src/nix/flake.cc

@@ -1462,12 +1462,6 @@ struct CmdFlake : NixMultiCommand
           #include "flake.md"
           ;
     }
-
-    void run() override
-    {
-        experimentalFeatureSettings.require(Xp::Flakes);
-        NixMultiCommand::run();
-    }
 };
 
 static auto rCmdFlake = registerCommand<CmdFlake>("flake");

src/nix/main.cc

@@ -412,7 +412,6 @@ void mainWrapped(int argc, char * * argv)
 
     if (argc == 2 && std::string(argv[1]) == "__dump-language") {
         experimentalFeatureSettings.experimentalFeatures = {
-            Xp::Flakes,
             Xp::FetchClosure,
             Xp::DynamicDerivations,
             Xp::FetchTree,

src/nix/nix.md

@@ -69,11 +69,9 @@ That is, Nix will operate on the default flake output attribute of the flake in
 ### Flake output attribute
 
 > **Warning** \
-> Flake output attribute installables depend on both the
+> Flake output attribute installables depend on the
-> [`flakes`](@docroot@/contributing/experimental-features.md#xp-feature-flakes)
-> and
 > [`nix-command`](@docroot@/contributing/experimental-features.md#xp-feature-nix-command)
-> experimental features, and subject to change without notice.
+> experimental feature, and subject to change without notice.
 
 Example: `nixpkgs#hello`
 

src/nix/repl.md

@@ -36,7 +36,7 @@ R""(
   Loading Installable ''...
   Added 1 variables.
 
-  # nix repl --extra-experimental-features 'flakes' nixpkgs
+  # nix repl nixpkgs
   Loading Installable 'flake:nixpkgs#'...
   Added 5 variables.
 

tests/functional/ca/selfref-gc.sh

@@ -4,7 +4,7 @@ source common.sh
 
 requireDaemonNewerThan "2.4pre20210626"
 
-enableFeatures "ca-derivations nix-command flakes"
+enableFeatures "ca-derivations nix-command"
 
 export NIX_TESTS_CA_BY_DEFAULT=1
 cd ..

tests/functional/common/init.sh

@@ -12,7 +12,7 @@ if isTestOnNixOS; then
   ! test -e "$test_nix_conf"
   cat > "$test_nix_conf_dir/nix.conf" <<EOF
 # TODO: this is not needed for all tests and prevents stable commands from be tested in isolation
-experimental-features = nix-command flakes
+experimental-features = nix-command
 flake-registry = $TEST_ROOT/registry.json
 show-trace = true
 EOF
@@ -58,7 +58,6 @@ EOF
 
 cat > "$NIX_CONF_DIR"/nix.conf.extra <<EOF
 fsync-metadata = false
-extra-experimental-features = flakes
 !include nix.conf.extra.not-there
 EOF
 

tests/functional/config.sh

@@ -59,13 +59,11 @@ var=$(nix config show | grep '^experimental-features =' | cut -d '=' -f 2 | xarg
 
 # Test that it's possible to load config from the environment
 prev=$(nix config show | grep '^cores' | cut -d '=' -f 2 | xargs)
-export NIX_CONFIG="cores = 4242"$'\n'"experimental-features = nix-command flakes"
+export NIX_CONFIG="cores = 4242"$'\n'"experimental-features = nix-command"
 exp_cores=$(nix config show | grep '^cores' | cut -d '=' -f 2 | xargs)
 exp_features=$(nix config show | grep '^experimental-features' | cut -d '=' -f 2 | xargs)
 [[ $prev != $exp_cores ]]
 [[ $exp_cores == "4242" ]]
-# flakes implies fetch-tree
-[[ $exp_features == "fetch-tree flakes nix-command" ]]
 
 # Test that it's possible to retrieve a single setting's value
 val=$(nix config show | grep '^warn-dirty' | cut -d '=' -f  2 | xargs)

tests/functional/experimental-features.sh

@@ -12,11 +12,11 @@ source common.sh
 #
 # function grep_both_ways {
 #     nix --experimental-features 'nix-command' "$@" | grepQuietInverse flake
-#     nix --experimental-features 'nix-command flakes' "$@" | grepQuiet flake
+#     nix --experimental-features 'nix-command' "$@" | grepQuiet flake
 #
 #     # Also, the order should not matter
 #     nix "$@" --experimental-features 'nix-command' | grepQuietInverse flake
-#     nix "$@" --experimental-features 'nix-command flakes' | grepQuiet flake
+#     nix "$@" --experimental-features 'nix-command' | grepQuiet flake
 # }
 #
 # # Simple case, the configuration effects the running command
@@ -29,50 +29,50 @@ source common.sh
 # with a warning if the experimental feature is not enabled. The order of the
 # `setting = value` lines in the configuration should not matter.
 
-# 'flakes' experimental-feature is disabled before, ignore and warn
+xpFeature=auto-allocate-uids
-NIX_CONFIG='
+gatedSetting=auto-allocate-uids
+
+# Experimental feature is disabled before, ignore and warn.
+NIX_CONFIG="
   experimental-features = nix-command
-  accept-flake-config = true
+  $gatedSetting = true
-' expect 1 nix config show accept-flake-config 1>"$TEST_ROOT"/stdout 2>"$TEST_ROOT"/stderr
+" expect 1 nix config show $gatedSetting 1>"$TEST_ROOT"/stdout 2>"$TEST_ROOT"/stderr
 [[ $(cat "$TEST_ROOT/stdout") = '' ]]
-grepQuiet "Ignoring setting 'accept-flake-config' because experimental feature 'flakes' is not enabled" "$TEST_ROOT/stderr"
+grepQuiet "error: could not find setting '$gatedSetting'" "$TEST_ROOT/stderr"
-grepQuiet "error: could not find setting 'accept-flake-config'" "$TEST_ROOT/stderr"
 
-# 'flakes' experimental-feature is disabled after, ignore and warn
+# Experimental feature is disabled after, ignore and warn.
-NIX_CONFIG='
+NIX_CONFIG="
-  accept-flake-config = true
+  $gatedSetting = true
   experimental-features = nix-command
-' expect 1 nix config show accept-flake-config 1>"$TEST_ROOT"/stdout 2>"$TEST_ROOT"/stderr
+" expect 1 nix config show $gatedSetting 1>"$TEST_ROOT"/stdout 2>"$TEST_ROOT"/stderr
 [[ $(cat "$TEST_ROOT/stdout") = '' ]]
-grepQuiet "Ignoring setting 'accept-flake-config' because experimental feature 'flakes' is not enabled" "$TEST_ROOT/stderr"
+grepQuiet "error: could not find setting '$gatedSetting'" "$TEST_ROOT/stderr"
-grepQuiet "error: could not find setting 'accept-flake-config'" "$TEST_ROOT/stderr"
 
-# 'flakes' experimental-feature is enabled before, process
+# Experimental feature is enabled before, process.
-NIX_CONFIG='
+NIX_CONFIG="
-  experimental-features = nix-command flakes
+  experimental-features = nix-command $xpFeature
-  accept-flake-config = true
+  $gatedSetting = true
-' nix config show accept-flake-config 1>"$TEST_ROOT"/stdout 2>"$TEST_ROOT"/stderr
+" nix config show $gatedSetting 1>"$TEST_ROOT"/stdout 2>"$TEST_ROOT"/stderr
 grepQuiet "true" "$TEST_ROOT/stdout"
-grepQuietInverse "Ignoring setting 'accept-flake-config'" "$TEST_ROOT/stderr"
 
-# 'flakes' experimental-feature is enabled after, process
+# Experimental feature is enabled after, process.
-NIX_CONFIG='
+NIX_CONFIG="
-  accept-flake-config = true
+  $gatedSetting = true
-  experimental-features = nix-command flakes
+  experimental-features = nix-command $xpFeature
-' nix config show accept-flake-config 1>"$TEST_ROOT"/stdout 2>"$TEST_ROOT"/stderr
+" nix config show $gatedSetting 1>"$TEST_ROOT"/stdout 2>"$TEST_ROOT"/stderr
 grepQuiet "true" "$TEST_ROOT/stdout"
-grepQuietInverse "Ignoring setting 'accept-flake-config'" "$TEST_ROOT/stderr"
+grepQuietInverse "Ignoring setting '$gatedSetting'" "$TEST_ROOT/stderr"
 
 function exit_code_both_ways {
-    expect 1 nix --experimental-features 'nix-command' "$@" 1>/dev/null
+    expect 1 nix --experimental-features 'nix-command ' "$@" 1>/dev/null
-    nix --experimental-features 'nix-command flakes' "$@" 1>/dev/null
+    nix --experimental-features "nix-command $xpFeature" "$@" 1>/dev/null
 
     # Also, the order should not matter
     expect 1 nix "$@" --experimental-features 'nix-command' 1>/dev/null
-    nix "$@" --experimental-features 'nix-command flakes' 1>/dev/null
+    nix "$@" --experimental-features "nix-command $xpFeature" 1>/dev/null
 }
 
-exit_code_both_ways show-config --flake-registry 'https://no'
+exit_code_both_ways config show --auto-allocate-uids
 
 # Double check these are stable
 nix --experimental-features '' --help 1>/dev/null

tests/functional/repl.sh

@@ -140,9 +140,9 @@ EOF
 testReplResponse '
 foo + baz
 ' "3" \
-    ./flake ./flake\#bar --experimental-features 'flakes'
+    ./flake ./flake\#bar
 
-# Test the `:reload` mechansim with flakes:
+# Test the `:reload` mechanism with flakes:
 # - Eval `./flake#changingThing`
 # - Modify the flake
 # - Re-eval it
@@ -153,7 +153,7 @@ sleep 1 # Leave the repl the time to eval 'foo'
 sed -i 's/beforeChange/afterChange/' flake/flake.nix
 echo ":reload"
 echo "changingThing"
-) | nix repl ./flake --experimental-features 'flakes')
+) | nix repl ./flake)
 echo "$replResult" | grepQuiet -s beforeChange
 echo "$replResult" | grepQuiet -s afterChange
 

tests/nixos/github-flakes.nix

@@ -143,7 +143,7 @@ in
           virtualisation.additionalPaths = [ pkgs.hello pkgs.fuse ];
           virtualisation.memorySize = 4096;
           nix.settings.substituters = lib.mkForce [ ];
-          nix.extraOptions = "experimental-features = nix-command flakes";
+          nix.extraOptions = "experimental-features = nix-command";
           networking.hosts.${(builtins.head nodes.github.networking.interfaces.eth1.ipv4.addresses).address} =
             [ "channels.nixos.org" "api.github.com" "github.com" ];
           security.pki.certificateFiles = [ "${cert}/ca.crt" ];

tests/nixos/sourcehut-flakes.nix

@@ -104,7 +104,7 @@ in
             virtualisation.memorySize = 4096;
             nix.settings.substituters = lib.mkForce [ ];
             nix.extraOptions = ''
-              experimental-features = nix-command flakes
+              experimental-features = nix-command
               flake-registry = https://git.sr.ht/~NixOS/flake-registry/blob/master/flake-registry.json
             '';
             environment.systemPackages = [ pkgs.jq ];

tests/nixos/tarball-flakes.nix

@@ -51,7 +51,7 @@ in
           virtualisation.additionalPaths = [ pkgs.hello pkgs.fuse ];
           virtualisation.memorySize = 4096;
           nix.settings.substituters = lib.mkForce [ ];
-          nix.extraOptions = "experimental-features = nix-command flakes";
+          nix.extraOptions = "experimental-features = nix-command";
         };
     };
 

tests/unit/libutil/config.cc

@@ -191,7 +191,7 @@ namespace nix {
             "description",
             {},
             true,
-            Xp::Flakes,
+            Xp::CaDerivations,
         };
         setting.assign("value");
 
@@ -203,7 +203,7 @@ namespace nix {
               "description": "description\n",
               "documentDefault": true,
               "value": "value",
-              "experimentalFeature": "flakes"
+              "experimentalFeature": "ca-derivations"
             }
           })#"_json);
     }