anchor.diff:        echo "export LD_DYLD_PATH=\"$dynamicLinker\"" >> $out/nix-support/setup-hook
       '')
   
  -    + optionalString (!nativeLibc) ''
  +    + optionalString (libc != null) ''
         # The "-B${libc_lib}/lib/" flag is a quick hack to force gcc to link
         # against the crt1.o from our own glibc, rather than the one in
         # /usr/lib.  (This is only an issue when using an `impure'
  
positive.code:       }
      ''
  
      + optionalString (!nativeLibc) (if (!targetPlatform.isDarwin) then ''
        dynamicLinker="${libc_lib}/lib/$dynamicLinker"
        echo $dynamicLinker > $out/nix-support/dynamic-linker
  
  
negative.code: assert nativeTools -> nativePrefix != "";
  assert !nativeTools ->
    cc != null && binutils != null && coreutils != null && gnugrep != null;
  assert !(nativeLibc && noLibc);
  assert (noLibc || nativeLibc) == (libc == null);
  
  # For ghdl (the vhdl language provider to gcc) we need zlib in the wrapper.
  assert cc.langVhdl or false -> zlib != null;
  