https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108796
--- Comment #9 from Aaron Ballman <aaron at aaronballman dot com> --- > GNU attributes are declaration specifiers *in the previous examples given > here*, not necessarily in all other cases. Thanks for clarifying! > (There is then logic in GCC to handle __attribute__ that, according to the > syntax, should appertain to a particular entity, so that it's instead > applied to some other related entity; for example, moving an attribute > from a declaration to its type. This is deliberately *not* done for [[]] > attribute syntax; those attributes are expected to be written in a correct > location for the entity they appertain to.) This touches on why I came to the decision I did in Clang. What `__attribute__` will apply to is sometimes inscrutable and users are (perhaps) used to it sliding around to whatever works. As you point out, `[[]]` doesn't have the same behavior; it has strict appertainment. Because `__attribute__` doesn't have strict appertainment, it did not seem like an issue for it to continue to shift around to whatever makes sense. Thus `[[]]` will apply to what the standard says it applies to, and `__attribute__` applies to whatever it should apply to based on the attribute names in the specifier, but users don't have to know whether they need to write `[[]] __attribute__(())` vs `__attribute__(()) [[]]`. (Clang also supports `__declspec`, so there are more combinations to worry about sometimes.) It really boils down to whether `__attribute__` is fundamentally a different "thing" than `[[]]` and I couldn't convince myself they were different. The result is, when the grammar allows consecutive attribute syntaxes, we parse all allowed syntaxes in a loop so users can write them in an arbitrary order.
