WG14 N2481 was adopted with minor modifications at the latest WG14 meetings.
The only modification to the paper was to correct the date for the deprecated
attribute to be 201904L (the corrected date value will be present in WG14
N2553 when it gets published).
__has_cpp_attribute is not available in C mode, and __has_c_attribute
should not be available in C++ mode. This also adds a test to
demonstrate that we properly handle scoped attribute tokens even in C
mode.
This gives library implementers a way to use standards-based attributes that do not conflict with user-defined macros of the same name. Attributes in C2x require this behavior normatively (C2x 6.7.11p4), but there's no reason to not have the same behavior in C++, especially given that such attributes may be used by a C library consumed by a C++ compilation.
llvm-svn: 369033
This behaves similar to the __has_cpp_attribute builtin macro in that it allows users to detect whether an attribute is supported with the [[]] spelling syntax, which can be enabled in C with -fdouble-square-bracket-attributes.
llvm-svn: 320088
Aaron Ballman