Ping
On Mon, Nov 24, 2014 at 10:02 AM, Aaron Ballman <[email protected]> wrote: > On Thu, Nov 20, 2014 at 7:22 PM, Richard Smith <[email protected]> wrote: >> On Thu, Nov 20, 2014 at 3:48 PM, Aaron Ballman <[email protected]> >> wrote: >>> >>> On Thu, Nov 20, 2014 at 6:27 PM, Richard Smith <[email protected]> >>> wrote: >>> > On Thu, Nov 20, 2014 at 1:38 PM, Aaron Ballman <[email protected]> >>> > wrote: >>> >> >>> >> The __has_attribute implementation does not pay attention to the >>> >> syntax supported by attributes -- instead, it looks to see whether an >>> >> attribute is generally known with that spelling. Since pragmas can now >>> >> be spelled as attributes, this means __has_attribute(loop) returns >>> >> true because of the #pragma loop functionality. Same for unroll. >>> >> >>> >> Should __has_attribute ignore attributes spelled with a #pragma >>> >> spelling? >>> > >>> > >>> > I would go further: __has_attribute should probably only look for >>> > GNU-syntax >>> > attributes. We have __has_cpp_attribute for C++-syntax attributes now, >>> > and I >>> > don't think anyone is (yet) using this for __declspec, so now seems like >>> > a >>> > good time to make this change. >>> >>> A long, long while back, we discussed having a way to determine >>> attributes by syntax, because that's sometimes important, as well as a >>> general query mechanism. >>> >>> How about adding: >>> >>> __has_declspec_attribute >>> __has_keyword_attribute >>> __has_gnu_attribute >>> >>> and leaving __has_attribute generic across syntaxes? >>> >>> This also reduces the chances of breaking code by allowing the >>> __has_attribute syntax to continue to work as it always has. >> >> >> Back when we only had GNU attributes, that's all it detected. I'm not >> convinced that people are actually using it for anything else, > > I believe I've seen some code using it for __declspec attributes. > IIRC, we may have run into this with MinGW, which implements > __declspec as a macro, replaced by __attribute__. > >> and I think >> it would be surprising if it said an attribute was supported but that >> attribute didn't work with GNU syntax. A generic-across-syntaxes >> __has_attribute is basically useless. > > The more I think about cross-syntax attribute checking, the more I > agree it's useless. > > I still think it would make sense to add the various forms of this, > and I definitely think that pragmas should be excluded from > __has_attribute. > > How does this sound as a path forward: > > * Change __has_attribute to only support GNU-style attributes. This > has the potential to break code, so this will require careful watching > of the lists. > * Add __has_declspec_attribute & __has_keyword_attribute, that only > apply to __declspecs and keywords. > > ~Aaron _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
