glibcCross: use a libgcc built separately from gcc

pkgs/development/compilers/gcc/common/builder.nix

@@ -3,7 +3,13 @@
 , enableMultilib
 }:
 
+let
+  forceLibgccToBuildCrtStuff =
+    import ./libgcc-buildstuff.nix { inherit lib stdenv; };
+in
+
 originalAttrs: (stdenv.mkDerivation (finalAttrs: originalAttrs // {
+  passthru = (originalAttrs.passthru or {}) // { inherit forceLibgccToBuildCrtStuff; };
   preUnpack = ''
     oldOpts="$(shopt -po nounset)" || true
     set -euo pipefail

pkgs/development/compilers/gcc/common/libgcc-buildstuff.nix

@@ -0,0 +1,37 @@
+{ lib
+, stdenv
+}:
+
+# Trick to build a gcc that is capable of emitting shared libraries *without* having the
+# targetPlatform libc available beforehand.  Taken from:
+#   https://web.archive.org/web/20170222224855/http://frank.harvard.edu/~coldwell/toolchain/
+#   https://web.archive.org/web/20170224235700/http://frank.harvard.edu/~coldwell/toolchain/t-linux.diff
+let
+  # crt{i,n}.o are the first and last (respectively) object file
+  # linked when producing an executable.  Traditionally these
+  # files are delivered as part of the C library, but on GNU
+  # systems they are in fact built by GCC.  Since libgcc needs to
+  # build before glibc, we can't wait for them to be copied by
+  # glibc.  At this early pre-glibc stage these files sometimes
+  # have different names.
+  crtstuff-ofiles =
+    if stdenv.targetPlatform.isPower
+    then "ecrti.o ecrtn.o ncrti.o ncrtn.o"
+    else "crti.o crtn.o";
+
+  # Normally, `SHLIB_LC` is set to `-lc`, which means that
+  # `libgcc_s.so` cannot be built until `libc.so` is available.
+  # The assignment below clobbers this variable, removing the
+  # `-lc`.
+  #
+  # On PowerPC we add `-mnewlib`, which means "libc has not been
+  # built yet".  This causes libgcc's Makefile to use the
+  # gcc-built `{e,n}crt{n,i}.o` instead of failing to find the
+  # versions which have been repackaged in libc as `crt{n,i}.o`
+  #
+  SHLIB_LC = lib.optionalString stdenv.targetPlatform.isPower "-mnewlib";
+
+in ''
+    echo 'libgcc.a: ${crtstuff-ofiles}' >> libgcc/Makefile.in
+    echo 'SHLIB_LC=${SHLIB_LC}' >> libgcc/Makefile.in
+  ''

pkgs/development/compilers/gcc/common/libgcc.nix

@@ -44,14 +44,14 @@ lib.optional (lib.versionAtLeast version "11.0")
     !langJit &&
     !stdenv.hostPlatform.isDarwin &&
     enableShared
-    ;
+  ;
 
-    # For some reason libgcc_s.so has major-version "2" on m68k but
-    # "1" everywhere else.  Might be worth changing this to "*".
-    libgcc_s-version-major =
-      if targetPlatform.isM68k
-      then "2"
-      else "1";
+  # For some reason libgcc_s.so has major-version "2" on m68k but
+  # "1" everywhere else.  Might be worth changing this to "*".
+  libgcc_s-version-major =
+    if targetPlatform.isM68k
+    then "2"
+    else "1";
 
 in
 (pkg: pkg.overrideAttrs (previousAttrs: lib.optionalAttrs ((!langC) || langJit || enableLibGccOutput) {

pkgs/development/compilers/gcc/common/pre-configure.nix

@@ -112,39 +112,5 @@ in lib.optionalString (hostPlatform.isSunOS && hostPlatform.is64bit) ''
   export inhibit_libc=true
 ''
 
-# Trick to build a gcc that is capable of emitting shared libraries *without* having the
-# targetPlatform libc available beforehand.  Taken from:
-#   https://web.archive.org/web/20170222224855/http://frank.harvard.edu/~coldwell/toolchain/
-#   https://web.archive.org/web/20170224235700/http://frank.harvard.edu/~coldwell/toolchain/t-linux.diff
 + lib.optionalString (targetPlatform != hostPlatform && withoutTargetLibc && enableShared)
-  (let
-
-    # crt{i,n}.o are the first and last (respectively) object file
-    # linked when producing an executable.  Traditionally these
-    # files are delivered as part of the C library, but on GNU
-    # systems they are in fact built by GCC.  Since libgcc needs to
-    # build before glibc, we can't wait for them to be copied by
-    # glibc.  At this early pre-glibc stage these files sometimes
-    # have different names.
-    crtstuff-ofiles =
-      if targetPlatform.isPower
-      then "ecrti.o ecrtn.o ncrti.o ncrtn.o"
-      else "crti.o crtn.o";
-
-    # Normally, `SHLIB_LC` is set to `-lc`, which means that
-    # `libgcc_s.so` cannot be built until `libc.so` is available.
-    # The assignment below clobbers this variable, removing the
-    # `-lc`.
-    #
-    # On PowerPC we add `-mnewlib`, which means "libc has not been
-    # built yet".  This causes libgcc's Makefile to use the
-    # gcc-built `{e,n}crt{n,i}.o` instead of failing to find the
-    # versions which have been repackaged in libc as `crt{n,i}.o`
-    #
-    SHLIB_LC = lib.optionalString targetPlatform.isPower "-mnewlib";
-
-  in ''
-    echo 'libgcc.a: ${crtstuff-ofiles}' >> libgcc/Makefile.in
-    echo 'SHLIB_LC=${SHLIB_LC}' >> libgcc/Makefile.in
-  '')
-
+  (import ./libgcc-buildstuff.nix { inherit lib stdenv; })

pkgs/development/libraries/gcc/libgcc/default.nix

@@ -0,0 +1,140 @@
+{ lib, stdenvNoLibs, buildPackages
+, gcc, glibc
+, libiberty
+}:
+
+let
+  stdenv = stdenvNoLibs;
+  gccConfigureFlags = gcc.cc.configureFlags ++ [
+    "--disable-fixincludes"
+    "--disable-intl"
+    "--enable-threads=posix"
+    "--with-glibc-version=${glibc.version}"
+
+    # these are required in order to prevent inhibit_libc=true,
+    # which will cripple libgcc's unwinder; see:
+    #  https://github.com/NixOS/nixpkgs/issues/213453#issuecomment-1616346163
+    "--with-headers=${lib.getDev glibc}/include"
+    "--with-native-system-header-dir=${lib.getDev glibc}${glibc.incdir or "/include"}"
+    "--with-build-sysroot=/"
+  ];
+
+in stdenv.mkDerivation (finalAttrs: {
+  pname = "libgcc";
+  inherit (gcc.cc) src version;
+
+  outputs = [ "out" "dev" ];
+
+  strictDeps = true;
+  depsBuildBuild = [ buildPackages.stdenv.cc ];
+  nativeBuildInputs = [ libiberty ];
+  buildInputs = [ glibc ];
+
+  postUnpack = ''
+    mkdir -p ./build
+    buildRoot=$(readlink -e "./build")
+  '';
+
+  postPatch =
+    gcc.cc.passthru.forceLibgccToBuildCrtStuff
+    + ''
+      sourceRoot=$(readlink -e "./libgcc")
+    '';
+
+  hardeningDisable = [ "pie" ];
+
+  preConfigure =
+  ''
+    # Drop in libiberty, as external builds are not expected
+    cd "$buildRoot"
+    (
+      mkdir -p build-${stdenv.buildPlatform.config}/libiberty/
+      cd build-${stdenv.buildPlatform.config}/libiberty/
+      ln -s ${buildPackages.libiberty}/lib/libiberty.a ./
+    )
+    mkdir -p "$buildRoot/gcc"
+    cd "$buildRoot/gcc"
+    (
+      # We "shift" the tools over to fake platforms perspective from the previous stage.
+      export AS_FOR_BUILD=${buildPackages.stdenv.cc}/bin/$AS_FOR_BUILD
+      export CC_FOR_BUILD=${buildPackages.stdenv.cc}/bin/$CC_FOR_BUILD
+      export CPP_FOR_BUILD=${buildPackages.stdenv.cc}/bin/$CPP_FOR_BUILD
+      export CXX_FOR_BUILD=${buildPackages.stdenv.cc}/bin/$CXX_FOR_BUILD
+      export LD_FOR_BUILD=${buildPackages.stdenv.cc.bintools}/bin/$LD_FOR_BUILD
+
+      export AS=$AS_FOR_BUILD
+      export CC=$CC_FOR_BUILD
+      export CPP=$CPP_FOR_BUILD
+      export CXX=$CXX_FOR_BUILD
+      export LD=$LD_FOR_BUILD
+
+      export AS_FOR_TARGET=${stdenv.cc}/bin/$AS
+      export CC_FOR_TARGET=${stdenv.cc}/bin/$CC
+      export CPP_FOR_TARGET=${stdenv.cc}/bin/$CPP
+      export LD_FOR_TARGET=${stdenv.cc.bintools}/bin/$LD
+
+      # We define GENERATOR_FILE so nothing bothers looking for GNU GMP.
+      export NIX_CFLAGS_COMPILE_FOR_BUILD+=' -DGENERATOR_FILE=1'
+
+      "$sourceRoot/../gcc/configure" ${lib.concatStringsSep " " gccConfigureFlags}
+
+      # We remove the `libgcc.mvar` deps so that the bootstrap xgcc isn't built.
+      sed -e 's,libgcc.mvars:.*$,libgcc.mvars:,' -i Makefile
+
+      make \
+        config.h \
+        libgcc.mvars \
+        tconfig.h \
+        tm.h \
+        options.h \
+        insn-constants.h \
+  '' + lib.optionalString stdenv.targetPlatform.isM68k ''
+        sysroot-suffix.h \
+  '' + lib.optionalString stdenv.targetPlatform.isArmv7 ''
+        arm-isa.h \
+        arm-cpu.h \
+  '' + ''
+        insn-modes.h
+    )
+    mkdir -p "$buildRoot/gcc/include"
+
+    # Preparing to configure + build libgcc itself
+    mkdir -p "$buildRoot/gcc/${stdenv.hostPlatform.config}/libgcc"
+    cd "$buildRoot/gcc/${stdenv.hostPlatform.config}/libgcc"
+    configureScript=$sourceRoot/configure
+    chmod +x "$configureScript"
+
+    export AS_FOR_BUILD=${buildPackages.stdenv.cc}/bin/$AS_FOR_BUILD
+    export CC_FOR_BUILD=${buildPackages.stdenv.cc}/bin/$CC_FOR_BUILD
+    export CPP_FOR_BUILD=${buildPackages.stdenv.cc}/bin/$CPP_FOR_BUILD
+    export CXX_FOR_BUILD=${buildPackages.stdenv.cc}/bin/$CXX_FOR_BUILD
+    export LD_FOR_BUILD=${buildPackages.stdenv.cc.bintools}/bin/$LD_FOR_BUILD
+
+    export AS=${stdenv.cc}/bin/$AS
+    export CC=${stdenv.cc}/bin/$CC
+    export CPP=${stdenv.cc}/bin/$CPP
+    export CXX=${stdenv.cc}/bin/$CXX
+    export LD=${stdenv.cc.bintools}/bin/$LD
+
+    export AS_FOR_TARGET=${stdenv.cc}/bin/$AS_FOR_TARGET
+    export CC_FOR_TARGET=${stdenv.cc}/bin/$CC_FOR_TARGET
+    export CPP_FOR_TARGET=${stdenv.cc}/bin/$CPP_FOR_TARGET
+    export LD_FOR_TARGET=${stdenv.cc.bintools}/bin/$LD_FOR_TARGET
+  '';
+
+  configurePlatforms = [ "build" "host" ];
+  configureFlags = [
+    "cross_compiling=true"
+    "--disable-gcov"
+    "--with-glibc-version=${glibc.version}"
+  ];
+
+  makeFlags = [ "MULTIBUILDTOP:=../" ];
+
+  postInstall = ''
+    moveToOutput "lib/gcc/${stdenv.hostPlatform.config}/${finalAttrs.version}/include" "$dev"
+    mkdir -p "$out/lib" "$dev/include"
+    ln -s "$out/lib/gcc/${stdenv.hostPlatform.config}/${finalAttrs.version}"/* "$out/lib"
+    ln -s "$dev/lib/gcc/${stdenv.hostPlatform.config}/${finalAttrs.version}/include"/* "$dev/include/"
+  '';
+})

pkgs/development/libraries/glibc/default.nix

@@ -4,6 +4,7 @@
 , withGd ? false
 , withLibcrypt? false
 , buildPackages
+, libgcc
 }:
 
 let
@@ -16,7 +17,7 @@ in
 
 (callPackage ./common.nix { inherit stdenv; } {
   inherit withLinuxHeaders withGd profilingLibraries withLibcrypt;
-  pname = "glibc" + lib.optionalString withGd "-gd";
+  pname = "glibc" + lib.optionalString withGd "-gd" + lib.optionalString (stdenv.cc.isGNU && libgcc==null) "-nolibgcc";
 }).overrideAttrs(previousAttrs: {
 
     # Note:
@@ -90,8 +91,8 @@ in
     #
     makeFlags =
       (previousAttrs.makeFlags or [])
-      ++ lib.optionals (stdenv.cc.cc?libgcc) [
-        "user-defined-trusted-dirs=${stdenv.cc.cc.libgcc}/lib"
+      ++ lib.optionals (libgcc != null) [
+        "user-defined-trusted-dirs=${libgcc}/lib"
       ];
 
     postInstall = previousAttrs.postInstall + (if stdenv.hostPlatform == stdenv.buildPlatform then ''
@@ -166,8 +167,8 @@ in
 
     passthru =
       (previousAttrs.passthru or {})
-      // lib.optionalAttrs (stdenv.cc.cc?libgcc) {
-        inherit (stdenv.cc.cc) libgcc;
+      // lib.optionalAttrs (libgcc != null) {
+        inherit libgcc;
       };
 
   meta = (previousAttrs.meta or {}) // { description = "The GNU C Library"; };

pkgs/test/cross/default.nix

@@ -115,6 +115,7 @@ let
   in
     pkgs.runCommand "test-mbuffer" {} ''
       echo hello | ${emulator} ${mbuffer}/bin/mbuffer
+      touch $out
     '';
 
   # This is meant to be a carefully curated list of builds/packages
@@ -127,13 +128,14 @@ let
   # of things that often break.  So, no buckshot `mapTestOnCross`
   # calls here.
   sanity = [
-    #pkgs.mbuffer              # https://github.com/NixOS/nixpkgs/issues/213453
+    mbuffer
     #pkgs.pkgsCross.gnu64.bash # https://github.com/NixOS/nixpkgs/issues/243164
     pkgs.gcc_multi.cc
     pkgs.pkgsMusl.stdenv
     pkgs.pkgsLLVM.stdenv
     pkgs.pkgsStatic.bash
     pkgs.pkgsCross.arm-embedded.stdenv
+    pkgs.pkgsCross.armv7l-hf-multiplatform.stdenv
     pkgs.pkgsCross.m68k.stdenv
     pkgs.pkgsCross.aarch64-multiplatform.pkgsBuildTarget.gcc
     pkgs.pkgsCross.powernv.pkgsBuildTarget.gcc

pkgs/top-level/aliases.nix

@@ -879,7 +879,6 @@ mapAliases ({
   liberation_ttf_v1_from_source = throw "'liberation_ttf_v1_from_source' has been renamed to/replaced by 'liberation_ttf_v1'"; # Converted to throw 2022-02-22
   liberation_ttf_v2_from_source = throw "'liberation_ttf_v2_from_source' has been renamed to/replaced by 'liberation_ttf_v2'"; # Converted to throw 2022-02-22
   liberationsansnarrow = throw "'liberationsansnarrow' has been renamed to/replaced by 'liberation-sans-narrow'"; # Converted to throw 2022-02-22
-  libgcc = throw "libgcc was removed, use gcc.cc.libgcc if needed"; # added 2023-05-13
   libgksu = throw "libgksu has been removed"; # Added 2022-01-16
   libgme = game-music-emu; # Added 2022-07-20
   libgnome_keyring = throw "'libgnome_keyring' has been renamed to/replaced by 'libgnome-keyring'"; # Converted to throw 2022-02-22

pkgs/top-level/all-packages.nix

@@ -18911,6 +18911,8 @@ with pkgs;
 
   librarian-puppet-go = callPackage ../development/tools/librarian-puppet-go { };
 
+  libgcc = stdenv.cc.cc.libgcc or null;
+
   # This is for e.g. LLVM libraries on linux.
   gccForLibs =
     if stdenv.targetPlatform == stdenv.hostPlatform && targetPackages.stdenv.cc.isGNU
@@ -21437,6 +21439,11 @@ with pkgs;
   # Being redundant to avoid cycles on boot. TODO: find a better way
   glibcCross = callPackage ../development/libraries/glibc {
     stdenv = gccCrossLibcStdenv; # doesn't compile without gcc
+    libgcc = callPackage ../development/libraries/gcc/libgcc {
+      gcc = gccCrossLibcStdenv.cc;
+      glibc = glibcCross.override { libgcc = null; };
+      stdenvNoLibs = gccCrossLibcStdenv;
+    };
   };
 
   muslCross = musl.override {