gcc: withoutTargetLibc: build libgcc_s.so

We want a `libgcc_s.so` to be built by the first stage
cross-compiler (withoutTargetLibc), since that is the compiler which
will compile the target libc.

This commit accomplishes that, by making three changes:

1. Replacing the `targetPlatform.libc == "msvcrt" &&` conditional
   with `enableShared`, so that the code which cross-build
   `libgcc_s.so` is used for all cross compilers capable of emitting
   shared libraries.

2. Removing the `targetPlatform == hostPlatform` guard from the code
   which produces the `libgcc` output.

3. Looking for build products in in "lib/${targetPlatform.config}/"
   rather than "lib/", so we will find them when cross compiling.

12 files changed, 27 insertions, 17 deletions

diff --git a/pkgs/development/compilers/gcc/10/default.nix b/pkgs/development/compilers/gcc/10/default.nix
index 9f49cc2b91f..c61093c67c0 100644
--- a/pkgs/development/compilers/gcc/10/default.nix
+++ b/pkgs/development/compilers/gcc/10/default.nix
@@ -295,5 +295,5 @@ lib.pipe (stdenv.mkDerivation ({
 // optionalAttrs (enableMultilib) { dontMoveLib64 = true; }
 ))
 [
-  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc; })
+  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc enableShared; })
 ]
diff --git a/pkgs/development/compilers/gcc/11/default.nix b/pkgs/development/compilers/gcc/11/default.nix
index c64fd0853f9..f61e51e2cab 100644
--- a/pkgs/development/compilers/gcc/11/default.nix
+++ b/pkgs/development/compilers/gcc/11/default.nix
@@ -307,6 +307,6 @@ lib.pipe (stdenv.mkDerivation ({
 // optionalAttrs (enableMultilib) { dontMoveLib64 = true; }
 ))
 [
-  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc; })
+  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc enableShared; })
   (callPackage ../common/checksum.nix { inherit langC langCC; })
 ]
diff --git a/pkgs/development/compilers/gcc/12/default.nix b/pkgs/development/compilers/gcc/12/default.nix
index bb48446c847..9665c2a9fe8 100644
--- a/pkgs/development/compilers/gcc/12/default.nix
+++ b/pkgs/development/compilers/gcc/12/default.nix
@@ -353,7 +353,7 @@ lib.pipe (stdenv.mkDerivation ({
 // optionalAttrs (enableMultilib) { dontMoveLib64 = true; }
 ))
 [
-  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc; })
+  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc enableShared; })
   (callPackage ../common/checksum.nix { inherit langC langCC; })
 ]
 
diff --git a/pkgs/development/compilers/gcc/13/default.nix b/pkgs/development/compilers/gcc/13/default.nix
index 19bb07669e5..1b73c251ce6 100644
--- a/pkgs/development/compilers/gcc/13/default.nix
+++ b/pkgs/development/compilers/gcc/13/default.nix
@@ -347,7 +347,7 @@ lib.pipe (stdenv.mkDerivation ({
 // optionalAttrs (enableMultilib) { dontMoveLib64 = true; }
 ))
 [
-  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc; })
+  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc enableShared; })
   (callPackage ../common/checksum.nix { inherit langC langCC; })
 ]
 
diff --git a/pkgs/development/compilers/gcc/4.8/default.nix b/pkgs/development/compilers/gcc/4.8/default.nix
index 6a40bd753a3..fa856eff96e 100644
--- a/pkgs/development/compilers/gcc/4.8/default.nix
+++ b/pkgs/development/compilers/gcc/4.8/default.nix
@@ -323,5 +323,5 @@ lib.pipe (stdenv.mkDerivation ({
 // optionalAttrs (enableMultilib) { dontMoveLib64 = true; }
 ))
 [
-  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc; })
+  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc enableShared; })
 ]
diff --git a/pkgs/development/compilers/gcc/4.9/default.nix b/pkgs/development/compilers/gcc/4.9/default.nix
index 41df57ffd4c..bab79f968db 100644
--- a/pkgs/development/compilers/gcc/4.9/default.nix
+++ b/pkgs/development/compilers/gcc/4.9/default.nix
@@ -350,5 +350,5 @@ lib.pipe (stdenv.mkDerivation ({
      '';}
 ))
 [
-  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc; })
+  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc enableShared; })
 ]
diff --git a/pkgs/development/compilers/gcc/6/default.nix b/pkgs/development/compilers/gcc/6/default.nix
index 1c1f4ae6cb3..f443babb4b7 100644
--- a/pkgs/development/compilers/gcc/6/default.nix
+++ b/pkgs/development/compilers/gcc/6/default.nix
@@ -368,5 +368,5 @@ lib.pipe (stdenv.mkDerivation ({
      '';}
 ))
 [
-  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc; })
+  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc enableShared; })
 ]
diff --git a/pkgs/development/compilers/gcc/7/default.nix b/pkgs/development/compilers/gcc/7/default.nix
index de6ccbb2efd..5b6ea7ead50 100644
--- a/pkgs/development/compilers/gcc/7/default.nix
+++ b/pkgs/development/compilers/gcc/7/default.nix
@@ -302,5 +302,5 @@ lib.pipe (stdenv.mkDerivation ({
 // optionalAttrs (enableMultilib) { dontMoveLib64 = true; }
 ))
 [
-  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc; })
+  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc enableShared; })
 ]
diff --git a/pkgs/development/compilers/gcc/8/default.nix b/pkgs/development/compilers/gcc/8/default.nix
index da4b1791008..f903e264b0a 100644
--- a/pkgs/development/compilers/gcc/8/default.nix
+++ b/pkgs/development/compilers/gcc/8/default.nix
@@ -277,5 +277,5 @@ lib.pipe (stdenv.mkDerivation ({
 // optionalAttrs (enableMultilib) { dontMoveLib64 = true; }
 ))
 [
-  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc; })
+  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc enableShared; })
 ]
diff --git a/pkgs/development/compilers/gcc/9/default.nix b/pkgs/development/compilers/gcc/9/default.nix
index 2d4e8a7524a..289212a1363 100644
--- a/pkgs/development/compilers/gcc/9/default.nix
+++ b/pkgs/development/compilers/gcc/9/default.nix
@@ -292,5 +292,5 @@ lib.pipe (stdenv.mkDerivation ({
 // optionalAttrs (enableMultilib) { dontMoveLib64 = true; }
 )
 ) [
-  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc; })
+  (callPackage ../common/libgcc.nix   { inherit version langC langCC langJit targetPlatform hostPlatform withoutTargetLibc enableShared; })
 ]
diff --git a/pkgs/development/compilers/gcc/common/configure-flags.nix b/pkgs/development/compilers/gcc/common/configure-flags.nix
index f395f9e0960..a60a3380ea2 100644
--- a/pkgs/development/compilers/gcc/common/configure-flags.nix
+++ b/pkgs/development/compilers/gcc/common/configure-flags.nix
@@ -66,6 +66,7 @@ let
       "--disable-threads"
       "--disable-libgomp"
       "--disable-libquadmath"
+      (lib.enableFeature enableShared "shared")
       "--disable-libatomic" # requires libc
       "--disable-decimal-float" # requires libc
       "--disable-libmpx" # requires libc
diff --git a/pkgs/development/compilers/gcc/common/libgcc.nix b/pkgs/development/compilers/gcc/common/libgcc.nix
index 19def2cbc4e..528d9d7d13a 100644
--- a/pkgs/development/compilers/gcc/common/libgcc.nix
+++ b/pkgs/development/compilers/gcc/common/libgcc.nix
@@ -4,6 +4,7 @@
 , langC
 , langCC
 , langJit
+, enableShared
 , targetPlatform
 , hostPlatform
 , withoutTargetLibc
@@ -18,7 +19,7 @@ drv: lib.pipe drv
   (pkg: pkg.overrideAttrs (previousAttrs:
     lib.optionalAttrs (
       targetPlatform != hostPlatform &&
-      targetPlatform.libc == "msvcrt" &&
+      enableShared &&
       withoutTargetLibc
     ) {
       makeFlags = [ "all-gcc" "all-target-libgcc" ];
@@ -33,11 +34,15 @@ drv: lib.pipe drv
 lib.optional (lib.versionAtLeast version "11.0")
 
 (let
+  targetPlatformSlash =
+    if hostPlatform.config == targetPlatform.config
+    then ""
+    else "${targetPlatform.config}/";
+
   enableLibGccOutput =
-    (with stdenv; targetPlatform == hostPlatform) &&
     !langJit &&
     !stdenv.hostPlatform.isDarwin &&
-    !stdenv.hostPlatform.isStatic
+    enableShared
     ;
 
 in
@@ -52,6 +57,10 @@ in
     lib.optionalString (!langC) ''
       rm -f $out/lib/libgcc_s.so*
     ''
+    + lib.optionalString (hostPlatform.config != targetPlatform.config) ''
+      mkdir -p $lib/lib/
+      ln -s ${targetPlatformSlash}lib $lib/lib
+    ''
 
     # TODO(amjoseph): remove the `libgcc_s.so` symlinks below and replace them
     # with a `-L${gccForLibs.libgcc}/lib` in cc-wrapper's
@@ -64,10 +73,10 @@ in
     + lib.optionalString enableLibGccOutput (''
       # move libgcc from lib to its own output (libgcc)
       mkdir -p $libgcc/lib
-      mv    $lib/lib/libgcc_s.so      $libgcc/lib/
-      mv    $lib/lib/libgcc_s.so.1    $libgcc/lib/
-      ln -s $libgcc/lib/libgcc_s.so   $lib/lib/
-      ln -s $libgcc/lib/libgcc_s.so.1 $lib/lib/
+      mv    $lib/${targetPlatformSlash}lib/libgcc_s.so      $libgcc/lib/
+      mv    $lib/${targetPlatformSlash}lib/libgcc_s.so.1    $libgcc/lib/
+      ln -s $libgcc/lib/libgcc_s.so   $lib/${targetPlatformSlash}lib/
+      ln -s $libgcc/lib/libgcc_s.so.1 $lib/${targetPlatformSlash}lib/
     ''
     #
     # Nixpkgs ordinarily turns dynamic linking into pseudo-static linking: