[PATCH] D66487: Fix -Wimplicit-fallthrough warnings in regcomp.c

[Aaron Ballman via Phabricator via llvm-commits]

aaron.ballman added a comment.

In D66487#1640019 <https://reviews.llvm.org/D66487#1640019>, @lebedev.ri wrote:

> Is this only about `lib/Support/regcomp.c`? Can that source simply be switched to C++?


We have other C files that may wish to use attributes, so I don't see that as a long-term solution.

In D66487#1639946 <https://reviews.llvm.org/D66487#1639946>, @Nathan-Huckleberry wrote:

> Maybe replace __has_cpp_attribute with something like this?
>
>   #ifndef has_cpp_attribute
>   #ifdef __cplusplus
>   # define has_cpp_attribute(x) __has_cpp_attribute(x)
>   #else
>   # define has_cpp_attribute(x) 0
>   #endif
>   #endif
>


That will run into the same issue -- you'll use `has_cpp_attribute(clang::something)` and in non-C++ mode, the `::` will cause an error. You need to hide the `::` behind the `__cplusplus` check.


Repository:
  rL LLVM

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https://reviews.llvm.org/D66487