clang-3.4 hangs on package alliance 5.0-20120515-6

[Nicolas Sévelin-Radiguet]

[04/09/2014 08:33 AM] Sylvestre Ledru:
> On 08/04/2014 23:28, Nicolas Sévelin-Radiguet wrote:
>> On 04/08/2014 10:51 PM, Sylvestre Ledru wrote:
>>> On 08/04/2014 21:36, Nicolas Sévelin-Radiguet wrote:
>>>> Hello everyone,
>>>>
>>>> While fixing some FTBFS with clang instead of gcc, I came across a bug
>>>> in clang (at least I think so).
>>>>
>>>> The package I am working on is alliance 5.0-20120515-6 [0] which is
>>>> failing to build due to -Wreturn-type errors [1]. After applying the
>>>> following patch [2] to get rid of these, clang hangs (eats CPU) and
>>>> nothing happens even after a few minutes [3].
>>>> The files needed to reproduce this behavior are here [4]:
>>>> - expy-0fa6b4.sh is the command line
>>>> - expy-0fa6b4.c is the source
>>>>
>>>> The source, with the patch applied, builds fine with gcc [5].
>>>> Please note that I am not familiar at all with this particular package.
>>> Is it this bug ?
>>> http://clang.debian.net/status.php?version=3.4&key=BUILD_TIMEOUT ?
>>> http://llvm.org/bugs/show_bug.cgi?id=16821
>>>
>>> Thanks
>>> S
>>>
>> Humm, looks like it.
>> When modifying the command line (the rest of the line being the same):
>> -D "_FORTIFY_SOURCE=2" -O2 hangs
>> -D "_FORTIFY_SOURCE=2" -O1 works
>> -O2 hangs
>> -O1 works.
>> So it looks like even without -D "_FORTIFY_SOURCE=2", clang hangs.
> Oh.
> A reduced test case of this file could help and, if different from bug
> 16821, please report it :)
>
> Thanks,
> Sylvestre
>
Hi,

Some news on this.
This is definitely not the same bug:
If I understand correctly, llvm bug 16821 refers to generated code which 
loops infinitely when executed. Am I right ?
If that's the case, I am not able to reproduce the test cases provided 
in the bug report. Can anyone confirm and/or correct me ?

The bug I have in the alliance package is about clang taking forever to 
compile the source. I will try to generated a reduced test case. It 
looks like c-reduce is the appropriate tool to do that, right ?

About the 'build time out' category on debian.clang.net, it looks like 
it is not related to bug 16821 (at least not all packages are). I was 
able to build some of them. Buildlogs are here: 
https://github.com/nonas/debian-clang/tree/master/tests/build_timeout/buildlogs
See files attempted.txt, failed.txt and successful.txt.
For instance, packages with 'checking whether compiler driver 
understands Ada' error messages may be affected by some kind of memory 
leak during the build process. During my build of these packages, I 
spotted that something was eating up all my RAM during the 'checking 
whether compiler driver understands Ada' part. My kernel OOM'ed a couple 
of times during these builds. Once again, if anyone could test some of 
these packages to confirm (or not) what I saw, that would be great. I 
didn't have time to look more into it (and autotools are complete 
strangers to me...)

Regards and congrats to the students chosen for the GSoC,
Nicolas