>> What I meant that mkmf could warn, if the current compiler differs with
>> rbconfig['CC'] compiler.
> 
> 
> Config::CONFIG['CC'] in rbconfig.rb is the current compiler.
> There is nothing else.
> 
   Oops, I just read the Guy's example again. You are right. Sorry
   about the confusion. How about adding RUBY_CC that tells the complier
   that was used to compiler ruby binary?

   - Ville