gcc: native aarch64-darwin support

pkgs/build-support/cc-wrapper/default.nix

@@ -432,14 +432,16 @@ stdenv.mkDerivation {
     # Always add -march based on cpu in triple. Sometimes there is a
     # discrepency (x86_64 vs. x86-64), so we provide an "arch" arg in
     # that case.
-    + optionalString ((targetPlatform ? gcc.arch) &&
+    # TODO: aarch64-darwin has mcpu incompatible with gcc
+    + optionalString ((targetPlatform ? gcc.arch) && (isClang || !(stdenv.isDarwin && stdenv.isAarch64)) &&
                       isGccArchSupported targetPlatform.gcc.arch) ''
       echo "-march=${targetPlatform.gcc.arch}" >> $out/nix-support/cc-cflags-before
     ''
 
     # -mcpu is not very useful. You should use mtune and march
     # instead. It’s provided here for backwards compatibility.
-    + optionalString (targetPlatform ? gcc.cpu) ''
+    # TODO: aarch64-darwin has mcpu incompatible with gcc
+    + optionalString ((targetPlatform ? gcc.cpu) && (isClang || !(stdenv.isDarwin && stdenv.isAarch64))) ''
       echo "-mcpu=${targetPlatform.gcc.cpu}" >> $out/nix-support/cc-cflags-before
     ''
 

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

@@ -72,6 +72,11 @@ let majorVersion = "11";
       ++ optional langFortran ../gfortran-driving.patch
       ++ optional (targetPlatform.libc == "musl" && targetPlatform.isPower) ../ppc-musl.patch
 
+      ++ optional (stdenv.isDarwin && stdenv.isAarch64) (fetchpatch {
+        url = "https://github.com/fxcoudert/gcc/compare/releases/gcc-11.1.0...gcc-11.1.0-arm-20210504.diff";
+        sha256 = "sha256-JqCGJAfbOxSmkNyq49aFHteK/RFsCSLQrL9mzUCnaD0=";
+      })
+
       # Obtain latest patch with ../update-mcfgthread-patches.sh
       ++ optional (!crossStageStatic && targetPlatform.isMinGW) ./Added-mcf-thread-model-support-from-mcfgthread.patch;
 
@@ -103,9 +108,15 @@ stdenv.mkDerivation ({
 
   hardeningDisable = [ "format" "pie" ];
 
+  postPatch = ''
+    configureScripts=$(find . -name configure)
+    for configureScript in $configureScripts; do
+      patchShebangs $configureScript
+    done
+  ''
   # This should kill all the stdinc frameworks that gcc and friends like to
   # insert into default search paths.
-  prePatch = lib.optionalString hostPlatform.isDarwin ''
+  + lib.optionalString hostPlatform.isDarwin ''
     substituteInPlace gcc/config/darwin-c.c \
       --replace 'if (stdinc)' 'if (0)'
 
@@ -114,14 +125,8 @@ stdenv.mkDerivation ({
 
     substituteInPlace libgfortran/configure \
       --replace "-install_name \\\$rpath/\\\$soname" "-install_name ''${!outputLib}/lib/\\\$soname"
-  '';
-
-  postPatch = ''
-    configureScripts=$(find . -name configure)
-    for configureScript in $configureScripts; do
-      patchShebangs $configureScript
-    done
-  '' + (
+  ''
+  + (
     if targetPlatform != hostPlatform || stdenv.cc.libc != null then
       # On NixOS, use the right path to the dynamic linker instead of
       # `/lib/ld*.so'.

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

@@ -170,7 +170,8 @@ let
     ++ lib.optional javaAwtGtk "--enable-java-awt=gtk"
     ++ lib.optional (langJava && javaAntlr != null) "--with-antlr-jar=${javaAntlr}"
 
-    ++ (import ../common/platform-flags.nix { inherit (stdenv)  targetPlatform; inherit lib; })
+    # TODO: aarch64-darwin has clang stdenv and its arch and cpu flag values are incompatible with gcc
+    ++ lib.optional (!(stdenv.isDarwin && stdenv.isAarch64)) (import ../common/platform-flags.nix { inherit (stdenv)  targetPlatform; inherit lib; })
     ++ lib.optionals (targetPlatform != hostPlatform) crossConfigureFlags
     ++ lib.optional (targetPlatform != hostPlatform) "--disable-bootstrap"
 

pkgs/top-level/all-packages.nix

@@ -10350,7 +10350,9 @@ in
     else ../development/compilers/gcc/10);
   gcc = if (with stdenv.targetPlatform; isVc4 || libc == "relibc")
     then gcc6 else
-      if stdenv.targetPlatform.isAarch64 then gcc9 else gcc10;
+      # aarch64-darwin doesn't support earlier gcc
+      if (stdenv.targetPlatform.isAarch64 && stdenv.isDarwin) then gcc11
+      else if stdenv.targetPlatform.isAarch64 then gcc9 else gcc10;
   gcc-unwrapped = gcc.cc;
 
   gccStdenv = if stdenv.cc.isGNU then stdenv else stdenv.override {
@@ -10562,7 +10564,8 @@ in
 
   gcc_latest = gcc11;
 
-  gfortran = gfortran9;
+  # aarch64-darwin doesn't support earlier gcc
+  gfortran = if (stdenv.isDarwin && stdenv.isAarch64) then gfortran11 else gfortran9;
 
   gfortran48 = wrapCC (gcc48.cc.override {
     name = "gfortran";
@@ -10650,7 +10653,8 @@ in
     inherit (gnome2) libart_lgpl;
   });
 
-  gnat = gnat9;
+  # aarch64-darwin doesn't support earlier gcc
+  gnat = if (stdenv.isDarwin && stdenv.isAarch64) then gnat11 else gnat9;
 
   gnat6 = wrapCC (gcc6.cc.override {
     name = "gnat";