gcc: Put runtime libraries in a separate output

GCC provides a number of libraries that are used by programs built by
GCC, in particular libgcc_s.so and libstdc++.so.  This caused programs
that used these libraries to have a runtime dependency on all of GCC
(~77 MiB).  Now they only depend on the "lib" output of GCC (~1.6
MiB).

With this and previous multiple-output improvements, closure sizes are
reduced a lot:

hello:       41 MiB -> 22 MiB
patchelf:   118 MiB -> 23 MiB
pan:        364 MiB -> 90 MiB

pkgs/build-support/gcc-wrapper/builder.sh

@@ -39,9 +39,9 @@ if test -n "$nativeTools"; then
     ldPath="$nativePrefix/bin"
 else
     if test -e "$gcc/lib64"; then
-        gccLDFlags="$gccLDFlags -L$gcc/lib64"
+        gccLDFlags="$gccLDFlags -L$gcc_lib/lib64"
     fi
-    gccLDFlags="$gccLDFlags -L$gcc/lib"
+    gccLDFlags="$gccLDFlags -L$gcc_lib/lib"
     if [ -n "$langVhdl" ]; then
         gccLDFlags="$gccLDFlags -L$zlib/lib"
     fi

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

@@ -40,6 +40,7 @@ stdenv.mkDerivation {
   addFlags = ./add-flags;
   
   inherit nativeTools nativeLibc nativePrefix gcc;
+  gcc_lib = gcc.lib or gcc;
   libc = if nativeLibc then null else libc;
   libc_dev = if nativeLibc then null else libc.dev or libc;
   libc_bin = if nativeLibc then null else libc.bin or libc;

pkgs/development/compilers/gcc/4.6/builder.sh

@@ -8,9 +8,10 @@ mkdir $NIX_FIXINC_DUMMY
 if test "$staticCompiler" = "1"; then
     EXTRA_LDFLAGS="-static"
 else
-    EXTRA_LDFLAGS=""
+    EXTRA_LDFLAGS="-Wl,-rpath,$lib/lib"
 fi
 
+
 # GCC interprets empty paths as ".", which we don't want.
 if test -z "$CPATH"; then unset CPATH; fi
 if test -z "$LIBRARY_PATH"; then unset LIBRARY_PATH; fi
@@ -205,6 +206,10 @@ preInstall() {
 
 
 postInstall() {
+    # Move runtime libraries to $lib.
+    mkdir -p $lib/lib
+    mv -v $out/lib/lib*.so $out/lib/lib*.so.*[0-9] $lib/lib/
+
     # Remove precompiled headers for now.  They are very big and
     # probably not very useful yet.
     find $out/include -name "*.gch" -exec rm -rf {} \; -prune
@@ -216,6 +221,7 @@ postInstall() {
 
     # More dependencies with the previous gcc or some libs (gccbug stores the build command line)
     rm -rf $out/bin/gccbug
+
     # Take out the bootstrap-tools from the rpath, as it's not needed at all having $out
     for i in $out/libexec/gcc/*/*/*; do
         if PREV_RPATH=`patchelf --print-rpath $i`; then

pkgs/development/compilers/gcc/4.6/default.nix

@@ -192,6 +192,10 @@ stdenv.mkDerivation ({
     inherit langC langCC langFortran langJava langAda langGo;
   };
 
+  outputs = [ "out" "lib" ];
+
+  setOutputConfigureFlags = false;
+
   inherit patches enableMultilib;
 
   libc_dev = stdenv.gcc.libc_dev;

pkgs/stdenv/linux/default.nix

@@ -193,9 +193,9 @@ rec {
   stdenvLinuxGlibc = stdenvLinuxBoot2Pkgs.glibc;
 
 
-  # 6) Construct a third stdenv identical to the 2nd, except that
+  # 6) Construct a third stdenv identical to the 2nd, except that this
-  #    this one uses the Glibc built in step 3.  It still uses
+  #    one uses the Glibc built in step 3.  It still uses the recent
-  #    the recent binutils and rest of the bootstrap tools, including GCC.
+  #    binutils and the rest of the bootstrap tools, including GCC.
   stdenvLinuxBoot3 = stdenvBootFun {
     gcc = wrapGCC {
       binutils = stdenvLinuxBoot1Pkgs.binutils;

pkgs/top-level/all-packages.nix

@@ -2254,6 +2254,7 @@ let
   }));
 
   gcc46_real = lowPrio (wrapGCC (callPackage ../development/compilers/gcc/4.6 {
+    stdenv = stdenvMulti;
     inherit noSysDirs;
 
     # bootstrapping a profiled compiler does not work in the sheevaplug: