anchor.diff:      ++ (optionals javaAwtGtk ([ gtk libart_lgpl ] ++ xlibs))
       ++ (optionals (cross != null) [binutilsCross])
       ++ (optionals langAda [gnatboot])
  -    ++ (optionals langVhdl [gnat])
  -
  -    # The builder relies on GNU sed (for instance, Darwin's `sed' fails with
  -    # "-i may not be used with stdin"), and `stdenvNative' doesn't provide it.
  -    ++ (optional stdenv.isDarwin gnused)
  -    ++ (optional stdenv.isDarwin binutils)
  -    ;
  +    ++ (optionals langVhdl [gnat]);
   
     NIX_LDFLAGS = stdenv.lib.optionalString  stdenv.isSunOS "-lm -ldl";
   
  
positive.code:     else null;
  
    passthru =
      { inherit langC langCC langObjC langObjCpp langAda langFortran langVhdl langGo version; isGNU = true; };
  
    inherit enableParallelBuilding enableMultilib;
  
  
negative.code: 
  # LTO needs libelf and zlib.
  assert libelf != null -> zlib != null;
  
  # The go frontend is written in c++
  assert langGo -> langCC;
  