[LLVMdev] Apple's GCC and .s/.S files in llvm-test (fwd)

Chris Lattner sabre at nondot.org
Tue Mar 25 11:28:27 PDT 2008

On Tue, 25 Mar 2008, Dale Johannesen wrote:
>> On Mar 24, 2008, at 5:40 PM, Dale Johannesen wrote:
>> [...]
>>>  I don't see a good way to do
>>> full-line comments that works both if you run the preprocessor and if
>>> you don't.
>> Could you use "##" instead of "#"?
> Pragmatically, that works (as I'm sure you know).   Digging into the
> legalities of C99 I'm not sure that it's guaranteed to work, though.
> Unknown directives actually match the "non-directive" case in the
> grammar in 6.10; while nothing is said anywhere about semantics that I
> can find, I'm not sure why gcc feels this should be a hard error at
> all....

I think that this is an extremely clever hack, and is nice and simple.  It 
works because ## is a token that just gets passed through when not in a 
macro replacement list.  Because of maximal munch, it prevents the 
preprocessor from seeing it as a #.

Dale, do you see any problem with changing the "comment character" to 



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