Improved support for building 32-bit binaries on x86_64-linux.

* glibc_multi: a wrapper that combines the 32-bit and 64-bit Glibcs.
  This is necessary so that 64-bit GCC can find gnu/stubs-32.h and the
  32-bit Glibc libraries.

  To build glibc_multi on x86_64-linux, you still need either the
  i686-linux Glibc derivation from a channel, or to have configured
  Nix with support for forwarding the build to a i686-linux machine.
  In the future this may become unnecessary by providing a prebuilt
  binary of 32-bit Glibc somewhere (like the binaries used in the
  stdenvLinux bootstrap).

* With glibc_multi, it becomes possible to build gcc with multilib
  support (i.e. it builds 32-bit and 64-bit versions of libgcc,
  libstdc++, etc.).

svn path=/nixpkgs/trunk/; revision=12203

pkgs/development/compilers/gcc-4.3/default.nix

@@ -5,6 +5,7 @@
 , texinfo ? null
 , gmp, mpfr
 , bison ? null, flex ? null
+, enableMultilib ? false
 }:
 
 assert langC;
@@ -43,6 +44,7 @@ stdenv.mkDerivation {
     ++ optionals langTreelang [bison flex];
 
   configureFlags = "
+    ${if enableMultilib then "" else "--disable-multilib"}
     --disable-libstdcxx-pch
     --with-system-zlib
     --enable-languages=${
@@ -60,8 +62,8 @@ stdenv.mkDerivation {
   NIX_EXTRA_LDFLAGS = if staticCompiler then "-static" else "";
 
   inherit gmp mpfr;
-
-  passthru = { inherit langC langCC langFortran langTreelang; };
+  
+  passthru = { inherit langC langCC langFortran langTreelang enableMultilib; };
 
   meta = {
     homepage = "http://gcc.gnu.org/";