[FFmpeg-devel] [PATCH 4/7] Use alias-safe types in AV_[RW] macros

Alexander Strange astrange
Fri Feb 19 07:31:40 CET 2010

On Feb 18, 2010, at 11:46 AM, Jason Garrett-Glaser wrote:

>> According to Jason, gcc seemed to require those attributes in some
>> cases even with the unions.  Ask him for details.
> I think astrange can probably explain better than I can.
> Dark Shikari

It's documented here:

Their conclusion (from reading some arguments on lists) is that the C99 spec isn't worded well here; it might be rewritten in C1x.

Unfortunate side note, -Wstrict-aliasing doesn't even catch some cases:

llvm doesn't implement strict-aliasing in the first place, so it doesn't provide better warnings here. I don't know how good icc or other compilers are.

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