Correct misuses of __has_cpp_attribute
#4812
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`__has_cpp_attribute` is for detecting support for attribute-tokens like `fallthrough` or `unlikely`. This queries with feature-test macro names are always going to fail: no implementation will ever support an attribute-token with the same name as a feature-test macro. Given the conditional use of library facilities, the intent here was clearly to test the feature-test macros to determine support for those facilities, so let's do that instead. I've also fixed the using-declaration for `std::to_underlying`. Drive-by: Removed extraneous `inline` in the definition of the `constexpr` `to_underlying` fallback; `constexpr` functions are implicitly inline.
CaseyCarter
commented
Oct 18, 2024
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Pull Request Prelude
Changes Proposed
__has_cpp_attributeis for detecting support for attribute-tokens likefallthroughorunlikely. These queries with feature-test macro names are always going to fail since no implementation will ever support an attribute-token with the same name as a feature-test macro. Given the conditional use of library facilities, the intent here is clearly to test the feature-test macros to determine support for those facilities, so let's do that instead.I've also fixed the using-declaration for
std::to_underlying.Drive-by: Removed extraneous
inlinein the definition of theconstexprfallback forto_underlying;constexprfunctions are implicitly inline.Issues addressed: None