gfortran/gcc: simplify & clean up on Darwin

This should eliminate the branched logic for gfortran on Darwin, as well
as preventing accidental inclusion of impure paths in gcc and gfortran
builds.

pkgs/development/compilers/gcc/5/default.nix

@@ -76,7 +76,8 @@ let version = "5.4.0";
       ++ optional langAda ../gnat-cflags.patch
       ++ optional langFortran ../gfortran-driving.patch
 
-      # This could be applied unconditionally but I don't want to cause a full Linux rebuild.
+      # This could be applied unconditionally but I don't want to cause a full
+      # Linux rebuild.
       ++ optional stdenv.cc.isClang ./libcxx38-and-above.patch;
 
     javaEcj = fetchurl {
@@ -234,6 +235,13 @@ stdenv.mkDerivation ({
 
   libc_dev = stdenv.cc.libc_dev;
 
+  # This should kill all the stdinc frameworks that gcc and friends like to
+  # insert into default search paths.
+  prePatch = if stdenv.isDarwin then ''
+    substituteInPlace gcc/config/darwin-c.c \
+      --replace 'if (stdinc)' 'if (0)'
+  '' else null;
+
   postPatch =
     if (stdenv.isGNU
         || (libcCross != null                  # e.g., building `gcc.crossDrv'

pkgs/development/compilers/gcc/gfortran-darwin.nix

@@ -1,52 +0,0 @@
-# This is a derivation specific to OS X (Darwin)
-{gmp, mpfr, libmpc, isl_0_14, cloog, zlib, fetchurl, stdenv
-
-, Libsystem
-}:
-
-stdenv.mkDerivation rec {
-  name = "gfortran-${version}";
-  version = "5.1.0";
-
-  buildInputs = [ gmp mpfr libmpc isl_0_14 cloog zlib ];
-
-  src = fetchurl {
-    url = "mirror://gnu/gcc/gcc-${version}/gcc-${version}.tar.bz2";
-    sha256 = "1bd5vj4px3s8nlakbgrh38ynxq4s654m6nxz7lrj03mvkkwgvnmp";
-  };
-
-  patches = ./gfortran-darwin.patch;
-
-  hardeningDisable = [ "format" ];
-
-  configureFlags = ''
-    --disable-bootstrap
-    --disable-cloog-version-check
-    --disable-isl-version-check
-    --disable-multilib
-    --enable-checking=release
-    --enable-languages=fortran
-    --with-cloog=${cloog}
-    --with-gmp=${gmp.dev}
-    --with-isl=${isl_0_14}
-    --with-mpc=${libmpc}
-    --with-mpfr=${mpfr.dev}
-    --with-native-system-header-dir=${Libsystem}/include
-    --with-system-zlib
-  '';
-
-  postConfigure = ''
-    export DYLD_LIBRARY_PATH=`pwd`/`uname -m`-apple-darwin`uname -r`/libgcc
-  '';
-
-  makeFlags = [ "CC=clang" ];
-
-  passthru.cc = stdenv.cc.cc;
-
-  meta = with stdenv.lib; {
-    description = "GNU Fortran compiler, part of the GNU Compiler Collection";
-    homepage    = "https://gcc.gnu.org/fortran/";
-    license     = licenses.gpl3Plus;
-    platforms   = platforms.darwin;
-  };
-}

pkgs/development/compilers/gcc/gfortran-darwin.patch

@@ -1,26 +0,0 @@
---- a/gcc/config/darwin-c.c	2015-01-09 22:18:42.000000000 +0200
-+++ b/gcc/config/darwin-c.c	2015-06-27 04:17:58.000000000 +0300
-@@ -490,8 +490,7 @@
- 
- static const char *framework_defaults [] =
-   {
--    "/System/Library/Frameworks",
--    "/Library/Frameworks",
-+// stdenvDarwinPure
-   };
- 
- /* Register the GNU objective-C runtime include path if STDINC.  */
- 
- /* Register the GNU objective-C runtime include path if STDINC.  */
---- a/gcc/cppdefault.c	2015-01-05 14:33:28.000000000 +0200
-+++ b/gcc/cppdefault.c	2015-06-27 04:16:15.000000000 +0300
-@@ -35,6 +35,9 @@
- # undef CROSS_INCLUDE_DIR
- #endif
- 
-+// stdenvDarwinPure
-+# undef LOCAL_INCLUDE_DIR
-+
- const struct default_include cpp_include_defaults[]
- #ifdef INCLUDE_DEFAULTS
- = INCLUDE_DEFAULTS;

pkgs/top-level/all-packages.nix

@@ -5058,10 +5058,7 @@ with pkgs;
     isl = if !stdenv.isDarwin then isl_0_14 else null;
   }));
 
-  gfortran = if !stdenv.isDarwin then gfortran5
-             else callPackage ../development/compilers/gcc/gfortran-darwin.nix {
-    inherit (darwin) Libsystem;
-  };
+  gfortran = gfortran5;
 
   gfortran48 = wrapCC (gcc48.cc.override {
     name = "gfortran";