gccNGPackages_15: fix gfortran & libstdcxx (#424411)

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

@@ -726,6 +726,15 @@ stdenvNoCC.mkDerivation {
       echo "-isystem ${getDev libcxx}/include/c++/v1" >> $out/nix-support/libcxx-cxxflags
       echo "-stdlib=libc++" >> $out/nix-support/libcxx-ldflags
     ''
+    # GCC NG friendly libc++
+    + optionalString (libcxx != null && libcxx.isGNU or false) ''
+      for dir in ${getDev libcxx}/include/c++/*; do
+        echo "-isystem $dir" >> $out/nix-support/libcxx-cxxflags
+      done
+      for dir in ${getDev libcxx}/include/c++/*/${targetPlatform.config}; do
+        echo "-isystem $dir" >> $out/nix-support/libcxx-cxxflags
+      done
+    ''
 
     ##
     ## Initial CFLAGS

pkgs/development/compilers/gcc/ng/common/default.nix

@@ -121,6 +121,21 @@ makeScopeWithSplicing' {
       };
 
       gfortran = wrapCCWith rec {
+        cc = gccPackages.gfortran-unwrapped;
+        libcxx = targetGccPackages.libstdcxx;
+        bintools = binutils;
+        extraPackages = [
+          targetGccPackages.libgcc
+        ];
+        nixSupport.cc-cflags = [
+          "-B${targetGccPackages.libgcc}/lib"
+          "-B${targetGccPackages.libssp}/lib"
+          "-B${targetGccPackages.libatomic}/lib"
+          "-B${targetGccPackages.libgfortran}/lib/"
+        ];
+      };
+
+      gfortranNoLibgfortran = wrapCCWith rec {
         cc = gccPackages.gfortran-unwrapped;
         libcxx = targetGccPackages.libstdcxx;
         bintools = binutils;
@@ -211,7 +226,7 @@ makeScopeWithSplicing' {
 
       libgfortran = callPackage ./libgfortran {
         stdenv = overrideCC stdenv buildGccPackages.gcc;
-        inherit (buildGccPackages) gfortran;
+        gfortran = buildGccPackages.gfortranNoLibgfortran;
       };
 
       libstdcxx = callPackage ./libstdcxx {