glibcLocales: re-enable parallelism, refactor (#448829)

From 38e9742ed794febbc8caa4177df14d097607a2d9 Mon Sep 17 00:00:00 2001

From: Maximilian Bosch <maximilian@mbosch.me>

Date: Sun, 5 Oct 2025 12:45:25 +0200

Subject: [PATCH 1/2] localedata: allow reproducible & parallel install of

 locale-archive

The problem with the current approach is that N processes are compiling

a locale and updating the locale-archive at the same time. Hence,

there's a race which process gets to update the archive first and thus

the build is not reproducible[1].

This patch changes that by adding the `--no-archive` flag to the

`$(LOCALEDEF)` invocation in `build-one-locale` to parallelize the build

process in a race-free manner. A single `localedef --add-to-archive`

then adds all previously built locales to the archive.

[1] https://github.com/NixOS/nixpkgs/issues/245360

---

 localedata/Makefile | 6 ++++++

 1 file changed, 6 insertions(+)

diff --git a/localedata/Makefile b/localedata/Makefile

index 01b32348d4..13f7d3a2c4 100644

--- a/localedata/Makefile

+++ b/localedata/Makefile

@@ -538,8 +538,13 @@ LOCALEDEF=I18NPATH=. GCONV_PATH=$(common-objpfx)iconvdata LC_ALL=C \

 $(rtld-prefix) $(common-objpfx)locale/localedef

 install-locales: install-locale-archive

+define install-all-locales

+  $(LOCALEDEF) $$flags --add-to-archive `find $(inst_complocaledir) -maxdepth 1 -mindepth 1 -type d | sort`

+endef

+

 # Create and install the locale-archive file.

 install-locale-archive: $(INSTALL-SUPPORTED-LOCALE-ARCHIVE)

+	$(install-all-locales)

 # Create and install the locales individually (no archive).

 install-locale-files: $(INSTALL-SUPPORTED-LOCALE-FILES)

@@ -565,6 +570,7 @@ define build-one-locale

 	$(LOCALEDEF) $$flags --alias-file=../intl/locale.alias \

 		     -i locales/$$input -f charmaps/$$charset \

 		     $(addprefix --prefix=,$(install_root)) $$locale \

+		     --no-archive \

 	&& echo ' done';

 endef

-- 

2.50.1

From 887cb6906afa2b2d8abf35ccfc33ce7b8dc902f8 Mon Sep 17 00:00:00 2001

From: Maximilian Bosch <maximilian@mbosch.me>

Date: Sun, 5 Oct 2025 12:48:43 +0200

Subject: [PATCH 2/2] Makeconfig: make inst_complocaledir overridable

On NixOS, we build the locales in a separate package from glibc itself.

Also, packages aren't installed into a common location such as `/usr`,

but each package has its own unique prefix below `/nix/store`.

For us, the current state is a problem because `localedef` is built

in a different package and expects DESTDIR to be the unique

package-prefix of `glibc` itself. Our current workaround is to

invoke `localedef` with `--prefix=$TMPDIR` and copy the contents

to the correct prefix. This was doable without patching when

`localedef` was doing build & locale-archive creation at the

same time.

With the previous patch, the Makefile uses `$(inst_complocaledir)` to

tell localedef where the previously built locales are. In NixOS, we now

need to override `$(inst_complocaledir)` to point to

`$TMPDIR/$(glibc.out)`. Hence, this patch makes the variable overridable

from env.

---

 Makeconfig | 2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makeconfig b/Makeconfig

index 9eda4fa528..43d88325bc 100644

--- a/Makeconfig

+++ b/Makeconfig

@@ -197,7 +197,7 @@ inst_zonedir = $(install_root)$(zonedir)

 ifndef complocaledir

 complocaledir = $(libdir)/locale

 endif

-inst_complocaledir = $(install_root)$(complocaledir)

+inst_complocaledir ?= $(install_root)$(complocaledir)

 # Where to install the message catalog data files (which are

 # machine-independent).

-- 

2.50.1

        & https://github.com/NixOS/nixpkgs/pull/188492#issuecomment-1233802991

      */

      ./reenable_DT_HASH.patch

      # enable parallel & reproducible build of glibcLocales

      ./0001-localedata-allow-reproducible-parallel-install-of-lo.patch

      ./0002-Makeconfig-make-inst_complocaledir-overridable.patch

    ]

    /*

      NVCC does not support ARM intrinsics. Since <math.h> is pulled in by almost

# Glibc cannot have itself in its RPATH.

export NIX_NO_SELF_RPATH=1

postConfigure() {

    # Hack: get rid of the `-static' flag set by the bootstrap stdenv.

    # This has to be done *after* `configure' because it builds some

    # test binaries.

    export NIX_CFLAGS_LINK=

    export NIX_LDFLAGS_BEFORE=

    export NIX_DONT_SET_RPATH=1

    unset CFLAGS

}

genericBuild

  (

    finalAttrs: previousAttrs: {

      builder = ./locales-builder.sh;

      outputs = [ "out" ];

      LOCALEDEF_FLAGS = [

        (if stdenv.hostPlatform.isLittleEndian then "--little-endian" else "--big-endian")

      ];

      env = (previousAttrs.env or { }) // {

        LOCALEDEF_FLAGS = if stdenv.hostPlatform.isLittleEndian then "--little-endian" else "--big-endian";

        # Glibc cannot have itself in its RPATH.

        NIX_NO_SELF_RPATH = 1;

      };

      postConfigure = (previousAttrs.postConfigure or "") + ''

        # Hack: get rid of the `-static' flag set by the bootstrap stdenv.

        # This has to be done *after* `configure' because it builds some

        # test binaries.

        export NIX_CFLAGS_LINK=

        export NIX_LDFLAGS_BEFORE=

        export NIX_DONT_SET_RPATH=1

        unset CFLAGS

      '';

      preBuild =

        (previousAttrs.preBuild or "")

          # $TMPDIR/nix/store/...-glibc-.../lib/locale/locale-archive.

          LOCALEDEF_FLAGS+=" --prefix=$TMPDIR"

          mkdir -p $TMPDIR/"${buildPackages.glibc.out}/lib/locale"

          export inst_complocaledir="$TMPDIR/"${buildPackages.glibc.out}/lib/locale

          mkdir -p "$inst_complocaledir"

          echo 'C.UTF-8/UTF-8 \' >> ../glibc-2*/localedata/SUPPORTED

          # Hack to allow building of the locales (needed since glibc-2.12)

          sed -i -e 's,^$(rtld-prefix) $(common-objpfx)locale/localedef,localedef $(LOCALEDEF_FLAGS),' ../glibc-2*/localedata/Makefile

          substituteInPlace ../glibc-2*/localedata/Makefile \

            --replace-fail '$(rtld-prefix) $(common-objpfx)locale/localedef' 'localedef $(LOCALEDEF_FLAGS)'

        ''

        + lib.optionalString (!allLocales) ''

          # Check that all locales to be built are supported

          echo SUPPORTED-LOCALES='${toString locales}' > ../glibc-2*/localedata/SUPPORTED

        '';

      # Current `nixpkgs` way of building locales is not compatible with

      # parallel install. `locale-archive` is updated in parallel with

      # multiple `localedef` processes and causes non-deterministic result:

      #   https://github.com/NixOS/nixpkgs/issues/245360

      enableParallelBuilding = false;

      makeFlags = (previousAttrs.makeFlags or [ ]) ++ [

        "localedata/install-locales"

        "localedir=${placeholder "out"}/lib/locale"