[PATCH] D155064: [clang][SemaCXX] Diagnose tautological uses of consteval if and is_constant_evaluated

[Mark de Wever via Phabricator via cfe-commits]

Mordante added inline comments.


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Comment at: libcxx/include/__type_traits/is_constant_evaluated.h:31
+  return false;
+#endif
 }
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hazohelet wrote:
> Mordante wrote:
> > Why is this needed? Does this mean the builtin will fail in C++03 mode?
> `__libcpp_is_constant_evaluated` always returns false under C++03 or earlier, where constexpr isn't available. This is a fix to run libc++ tests without seeing warnings from clang with this patch.
> (Live demo: https://godbolt.org/z/oszebM5o5)
I see can you add a comment in that regard? To me it looks like the builtin fails in C++03, where returning false indeed is always the right answer.


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  https://reviews.llvm.org/D155064/new/

https://reviews.llvm.org/D155064