[Bug c/66970] Add __has_builtin() macro

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66970

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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           Keywords|                            |patch
   Target Milestone|---                         |10.0

--- Comment #22 from Martin Sebor <msebor at gcc dot gnu.org> ---
Patch: https://gcc.gnu.org/ml/gcc-patches/2019-10/msg00062.html