WIP: GCC with separated runtime libraries

pkgs/development/compilers/gcc-ng/11/default.nix

@@ -87,7 +87,6 @@ let
         targetGccLibraries.libunwind
       ];
       extraBuildCommands = ''
-        echo "-rtlib=libgcc -Wno-unused-command-line-argument" >> $out/nix-support/cc-cflags
         echo "-B${targetGccLibraries.libgcc}/lib" >> $out/nix-support/cc-cflags
       '' + lib.optionalString (!stdenv.targetPlatform.isWasm) ''
         echo "--unwindlib=libunwind" >> $out/nix-support/cc-cflags
@@ -105,7 +104,6 @@ let
         targetGccLibraries.libgcc
       ];
       extraBuildCommands = ''
-        echo "-rtlib=libgcc" >> $out/nix-support/cc-cflags
         echo "-B${targetGccLibraries.libgcc}/lib" >> $out/nix-support/cc-cflags
         echo "-nostdlib++" >> $out/nix-support/cc-cflags
       '' + mkExtraBuildCommands cc;
@@ -119,7 +117,6 @@ let
         targetGccLibraries.libgcc
       ];
       extraBuildCommands = ''
-        echo "-rtlib=libgcc" >> $out/nix-support/cc-cflags
         echo "-B${targetGccLibraries.libgcc}/lib" >> $out/nix-support/cc-cflags
       '' + mkExtraBuildCommands cc;
     };
@@ -150,6 +147,10 @@ let
 
     libada = callPackage ./libada { };
 
+    libatomic = callPackage ./libatomic {
+      stdenv = overrideCC stdenv buildGccTools.gccNoLibstdcxx;
+    };
+
     libgfortran = callPackage ./libgfortran { };
 
     libstdcxx = callPackage ./libstdcxx {

pkgs/development/compilers/gcc-ng/11/libatomic/default.nix

@@ -0,0 +1,54 @@
+{ lib, stdenv, buildPackages
+, gcc_src, version
+, glibc
+, autoreconfHook269, libiberty
+}:
+
+stdenv.mkDerivation rec {
+  pname = "libatomic";
+  inherit version;
+
+  src = gcc_src;
+
+  patches = [
+    ../custom-threading-model.patch
+  ];
+
+  outputs = [ "out" "dev" ];
+
+  strictDeps = true;
+
+  depsBuildBuild = [ buildPackages.stdenv.cc ];
+  nativeBuildInputs = [ autoreconfHook269 libiberty ];
+
+  enableParallelBuilding = true;
+
+  #postUnpack = ''
+  #  mkdir -p ./build
+  #  buildRoot=$(readlink -e "./build")
+  #'';
+
+  postPatch = ''
+    sourceRoot=$(readlink -e "./libatomic")
+  '';
+
+  configurePlatforms = [ "build" "host" ];
+  configureFlags = [
+    "--disable-dependency-tracking"
+    "--with-threads=single"
+    # $CC cannot link binaries, let alone run then
+    "cross_compiling=true"
+    # Do not have dynamic linker without libc
+    "--enable-static"
+    "--disable-shared"
+  ];
+
+  makeFlags = [ "MULTIBUILDTOP:=../" ];
+
+  postInstall = ''
+    moveToOutput "lib/gcc/${stdenv.hostPlatform.config}/${version}/include" "$dev"
+    mkdir -p "$out/lib" "$dev/include"
+    ln -s "$out/lib/gcc/${stdenv.hostPlatform.config}/${version}"/* "$out/lib"
+    ln -s "$dev/lib/gcc/${stdenv.hostPlatform.config}/${version}/include"/* "$dev/include/"
+  '';
+}

pkgs/development/compilers/gcc-ng/11/libgcc/default.nix

@@ -11,7 +11,7 @@ stdenv.mkDerivation rec {
   src = gcc_src;
 
   patches = [
-    ./libgcc-custom-threading-model.patch
+    ../custom-threading-model.patch
   ];
 
   outputs = [ "out" "dev" ];

pkgs/top-level/all-packages.nix

@@ -11053,7 +11053,9 @@ with pkgs;
 
   crossLibcStdenv =
     if stdenv.hostPlatform.useLLVM or false || stdenv.hostPlatform.isDarwin
-    then overrideCC stdenv buildPackages.llvmPackages.clangNoLibc
+      then overrideCC stdenv buildPackages.llvmPackages.clangNoLibc
+    else if stdenv.hostPlatform.useGccNg or false
+      then overrideCC stdenv buildPackages.gccNgPackages.gccNoLibc
     else gccCrossLibcStdenv;
 
   # The GCC used to build libc for the target platform. Normal gccs will be
@@ -11366,6 +11368,9 @@ with pkgs;
 
   gccNgPackages_11 = recurseIntoAttrs (callPackage ../development/compilers/gcc-ng/11 ({
     inherit (stdenvAdapters) overrideCC;
+    # These are the default arguments, but do this to avoid splicing which was
+    # causing infinite recursion.
+    inherit bintools bintoolsNoLibc;
     buildGccTools = buildPackages.gccNgPackages_11.tools;
     targetGccLibraries = targetPackages.gccNgPackages_11.libraries;
   }));