[cfe-commits] r142693 - in /cfe/trunk: lib/CodeGen/CGRTTI.cpp lib/Sema/SemaDeclAttr.cpp lib/Sema/SemaDeclCXX.cpp test/CodeGenCXX/weak-extern-typeinfo.cpp

[Aaron Ballman]

Thank you for the information, I'll continue to support it without
warning about it being an extension.

~Aaron

On Mon, Dec 2, 2013 at 11:54 AM, Douglas Gregor <dgregor at apple.com> wrote:
>
>> On Dec 2, 2013, at 9:20 AM, Aaron Ballman <aaron at aaronballman.com> wrote:
>>
>>> On Fri, Oct 21, 2011 at 6:27 PM, Fariborz Jahanian <fjahanian at apple.com> wrote:
>>> Author: fjahanian
>>> Date: Fri Oct 21 17:27:12 2011
>>> New Revision: 142693
>>>
>>> URL: http://llvm.org/viewvc/llvm-project?rev=142693&view=rev
>>> Log:
>>> c++: support gcc's application of weak attribute on
>>> class declaration which forces any such class and any
>>> class that inherits from such a class to have their
>>> typeinfo symbols be marked as weak.
>>> // rdar://10246395
>>
>> Sorry to resurrect an ancient commit, but I happened to be in the code
>> working on attribute subjects.
>>
>> As best I can tell, gcc does not support this construct. I used the
>> codegen test from this commit and got:
>>
>> http://ideone.com/2TxMtR
>> http://goo.gl/EU1HT9  (gcc.godbolt.com)
>>
>> It seems that it emits a warning in gcc: 'weak' attribute does not
>> apply to types.
>>
>> So the question becomes: should I continue to support weak on a class
>> declaration with my refactoring, should this feature be removed from
>> clang, or should there be a separate refactoring to note that this is
>> a clang-specific extension?
>
> It was an extension in Apple's GCC and yes, please continue to support this in your refactoring: it's still an important feature. We added the feature to Clang specifically because users of Apple GCC requested it.
>
>   - Doug