[Pixman] pixman on iOS

Jeremy Huddleston Sequoia jeremyhu at apple.com
Wed Nov 28 11:56:25 PST 2012

On Nov 28, 2012, at 11:52 AM, Siarhei Siamashka <siarhei.siamashka at gmail.com> wrote:

> On Fri, 02 Nov 2012 01:40:01 +0100
> sandmann at cs.au.dk (Søren Sandmann) wrote:
>> Siarhei Siamashka <siarhei.siamashka at gmail.com> writes:
>>>>> I would suggest to just change the order of checks for
>>>>> __declspec(thread) and __thread in configure.ac
>>>> We should maybe try using -Werror=ignored-attributes in the test, or
>>>> just prefer the first one.
>>> Using -Werror=ignored-attributes will not help because clang-3.1 (and
>>> maybe older versions too) just silently ignores __declspec(thread).
>>> This non-working TLS problem could have been detected by the pixman test
>>> suite if clang had OpenMP support. In any case, I was just lucky to
>>> notice the fresh warning when doing preemptive testing for the current
>>> clang svn (just to be sure that pixman would not need any ugly compiler
>>> bug workarounds for the upcoming clang-3.2).
>>> Regarding your original patch, how does iOS behave when somebody
>>> tries to use __thread keyword? Does it fail compilation?
>> If nobody knows the answer to this, let's just change the order of the
>> checks as you suggested. We can't support iOS unless someone is willing
>> to maintain it.
> Now it appears that this bug also affects mingw-w64, not just clang:
>    https://bugs.freedesktop.org/show_bug.cgi?id=57591
> I have sent a patch to change the order of checks, but another option
> to evaluate is to revert a069da6c66da407cc52e1e92321d69c68fd6beb5.
> Jeremy, it might look like I'm picking on you, but it would really help
> to get a confirmation that a069da6c66da407cc52e1e92321d69c68fd6beb5
> actually fixed some real problem on iOS. The commit message was a bit
> vague. Shit happens, I guess nobody here could have predicted that
> __declspec generally has such a weird behavior in modern compilers and
> everyone had time to review your patch before it got pushed. So it
> is not like you are the one to blame.

No worries.  I'm sorry, but I've been really slammed lately.  I'll take a look at this next week.  Feel free to assign the #57591 bug to me.

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