anchor.diff:        enableShared
   
         langC
  +      langD
         langCC
         langFortran
         langAda
  
positive.code: , langAda ? false
  , langObjC ? stdenv.targetPlatform.isDarwin
  , langObjCpp ? stdenv.targetPlatform.isDarwin
  , langGo ? false
  , reproducibleBuild ? true
  , profiledCompiler ? false
  
negative.code: assert langGo -> langCC;
  assert langAda -> gnatboot != null;
  
  # TODO: fixup D bootstapping, probably by using gdc11 (and maybe other changes).
  #   error: GDC is required to build d
  assert !langD;
  
  # threadsCross is just for MinGW
  assert threadsCross != null -> stdenv.targetPlatform.isWindows;
  
  