C++20 constexpr _Copy_s and simplify char8_t compare#861
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CaseyCarter
approved these changes
May 24, 2020
mnatsuhara
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May 26, 2020
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Thanks, @CaseyCarter, for these improvement ideas! |
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Followup to #491, in response to #491 (comment) and #491 (comment).
Mark our non-Standard extension
char_traits::_Copy_sandbasic_string_view::_Copy_sas_CONSTEXPR20. Similarly to how Misc constexpr #491 changedcopy, previously_Copy_swas alwaysconstexprinbasic_string_viewbut never inchar_traits; I similarly argue that this will not affect users because it would have required them to notice and provide a custom traits class (and in this case, the non-Standard extension is far more obscure than the Standard function). Making theseconstexprin C++20 mode only is simpler to explain.Simplify
char_traits::compareforchar8_t. This is possible becausememcmpand__builtin_memcmptakeconst void*and returnint, and their behavior is correct forchar8_t. The otheru8intrinsics are type-sensitive so they can't be unified like this.