[cfe-dev] Implementation of stddef.h

[Chris Lattner]

On May 18, 2008, at 3:23 PM, Eli Friedman wrote:

> On Sun, May 18, 2008 at 3:11 PM, Neil Booth <neil at daikokuya.co.uk>  
> wrote:
>> Eli Friedman wrote:-
>>
>>> Should I take the fact that there have been no comments as meaning  
>>> the
>>> patch is bad, the patch is okay, or just that nobody with the
>>> appropriate expertise had the time to take a look at it?
>>
>> One more thing - since these macros use __typeof__, are we ever
>> going to diagnose that as an extension?  If we do that might cause
>> a problem for user code, unless our diagnostic handlers can weasel
>> through the macro expansion level(s) and figure out it was actually
>> defined in a system header.
>
> AFAIK, we already suppress warnings in system headers.  And, at least
> for the moment, clang's implementation of -pedantic follows gcc's
> version in that we don't warn about the use of anything prefixed with
> double-underscore.  (Since it's reserved by the standard, it's not a
> constraint violation to use it, so we're conforming even if we don't
> warn.)

Right.  Another option for similar things is the __extension__ unary  
expression, which turns off extension warnings for its subexpression.

-Chris