[[deprecated]] applied to local variables

[cor3ntin]

GCC warns on local variables marked [[deprecated]]
https://compiler-explorer.com/z/nvfdTeveP

This behavior seems to be backed by the standard https://eel.is/c++draft/dcl.attr#deprecated-2.sentence-1

Should we follow suite? Arguably, it would be of limited usefulness.

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: cor3ntin (cor3ntin)

GCC warns on local variables marked `[[deprecated]]` https://compiler-explorer.com/z/nvfdTeveP

This behavior seems to be backed by the standard https://eel.is/c++draft/dcl.attr#deprecated-2.sentence-1

Should we follow suite? Arguably, it would be of limited usefulness.

[shafik]

Confirmed, seems like it has limited use but this at least documents we are aware of it.

[erichkeane]

I don't really see the usefulness, but I DEFINITELY think we should enforce it if we are going to permit it on local variable decls. At the moment, the the standard permits them on local variable decls, AND encourages enforcement, so we should.

However, if the response to cplusplus/CWG#530 results in disallowing 'local variables', that would be a valid solution ot this as well.

[shafik]

Note, if we remove the [[deprecated]] from f we warn for a now: https://compiler-explorer.com/z/f7o7Wc6W7