[llvm-testresults] Red bots at night, buildczar's delight?

[dalej]

OK, I guess no one else wants to express an opinion on this, so i went with this one.  Real-world code may have some problems down the road, but nothing that can't be fixed.

On Nov 17, 2010, at 4:35 PM, Chandler Carruth wrote:

> On Wed, Nov 17, 2010 at 11:33 AM, dalej <dalej at apple.com> wrote:
> 
> On Nov 17, 2010, at 10:39 AM, dalej wrote:
> >>>> clang-i386-darwin10 running the gcc testsuite developed 5 new failures (there are others, claimed by Rafael but not fixed) in the range 119343-119345 (build 1625).  That's Chandler and John; all the patches look unrelated to the failures to me, but obviously one of them isn't.
> 
> John analyzed this as:
> 
> >>> gcc.apple/default-x86_64-sse3.c has:
> >>> #include <pmmintrin.h>
> 
> ...which eventually includes <mm_malloc.h>, a gcc-supplied header....
> 
> >>> gcc's mm_malloc.h has:
> >>> #include <stdlib.h>
> >>>
> >>> After r119343, Clang's mm_malloc.h has:
> >>> #include <stddef.h>
> >>>
> >>> The test case contains a (spurious) call to exit().  Cue clang warning about exit() not being declared and dejagnu complaining about extra "errors".
> 
> I said:
> 
> > there's no reason <pmmintrin.h> should declare exit.  Test is broken, I'll fix.
> 
> 
> but on further consideration I'm not so sure.  gcc's *mmintrin.h files have been (indirectly) including <stdlib.h> forever, at least since 2004, and use of those headers is widespread in X86 code.  Removing <stdlib.h> breaks these 5 tests, and may well break user code.   I don't think these headers are covered by any standard, but I'm not seeing a good reason to break compatibility with gcc in this way.  Chandler, why did you do this?  Other opinions?
> 
> Sorry this broke stuff. =/
> 
> My motivation for the change was quite simple: this is a builtin header file, and as such a minimal set of system header includes is preferable. None is even more preferable as it provides for the use of the header in a freestanding context. When I've discussed this header in the past, the sentiment from Chris and others was that there was a general trend in both GCC and Clang to reduce the number of system headers included by builtin headers.
> 
> I'd vote for continuing the trend. This isn't the first time it has happened (GCC dropped errno.h from mm_malloc.h not too long ago) and I can't imagine it will be the last. It's hard to argue that we should match GCC on this front when in fact, GCC is a moving target here, and moving in the same direction if at a different speed.
> 
> I also cannot come up with a principled reason why any code should expect an *mmintrin.h header to provide the definitions within stdlib.h. 'exit()' in particular just doesn't make sense. I think finding this bad code and fixing it is the correct approach.

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