Dealing with compilers that pretend to be GCC

[Chris Lattner]

On Jan 31, 2012, at 4:58 AM, Marc Glisse wrote:
>>>> The docs say that ‘__has_builtin’ & co. are macros.  What do they expand to?
>>> 
>>> 0 or 1.
>> 
>> I understand.  To put it another way, how are they defined?
> 
> Compiler magic, like __LINE__ for instance? I am still not sure what you are asking...

Yes, they are compiler magic.  __has_attribute() __has_extension() etc all work the same way as well.

> Interestingly enough:
> $ cat q.c
> __has_builtin
> $ clang -E q.c
> <segfault>

Nice catch, fixed in r149397.  Thanks!

-Chris