This matches a similar behavior with GCC accepting [[gnu::__attr__]] as a alias for [[gnu::attr]] in that clang attributes can now be spelled with two leading and trailing underscores.
I had always intended for this to work, but missed the critical bit. We already had an existing test in test/Preprocessor/has_attribute.cpp for [[clang::__fallthrough__]] but using that spelling would still give an "unknown attribute" diagnostic.
llvm-svn: 346547
Currently, we only accept clang as the scoped attribute identifier for double square bracket attributes provided by Clang, but this has the potential to conflict with user-defined macros. To help alleviate these concerns, this introduces the _Clang scoped attribute identifier as an alias for clang. It also introduces a warning with a fixit on the off chance someone attempts to use __clang__ as the scoped attribute (which is a predefined compiler identification macro).
llvm-svn: 346521
ParsedAttr is using a hand-rolled trailing-objects
implementation that gets cleaned up quite a bit by
just using llvm::TrailingObjects. This is a large
TrailingObjects list, but most things are length '0'.
Differential Revision: https://reviews.llvm.org/D50531
llvm-svn: 339380
Aaron Ballman