warn-constant-evaluated-constexpr.cpp
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// RUN: %clang_cc1 -std=c++2a -fsyntax-only -verify %s
namespace std {
constexpr bool is_constant_evaluated() noexcept {
return __builtin_is_constant_evaluated();
}
} // namespace std
constexpr int fn1() {
if constexpr (std::is_constant_evaluated()) // expected-warning {{'std::is_constant_evaluated' will always evaluate to 'true' in a manifestly constant-evaluated expression}}
return 0;
else
return 1;
}
constexpr int fn2() {
if constexpr (!std::is_constant_evaluated()) // expected-warning {{'std::is_constant_evaluated' will always evaluate to 'true' in a manifestly constant-evaluated expression}}
return 0;
else
return 1;
}
constexpr int fn3() {
if constexpr (std::is_constant_evaluated() == false) // expected-warning {{'std::is_constant_evaluated' will always evaluate to 'true' in a manifestly constant-evaluated expression}}
return 0;
else
return 1;
}
constexpr int fn4() {
if constexpr (__builtin_is_constant_evaluated() == true) // expected-warning {{'__builtin_is_constant_evaluated' will always evaluate to 'true' in a manifestly constant-evaluated expression}}
return 0;
else
return 1;
}
constexpr int fn5() {
if constexpr (__builtin_is_constant_evaluated()) // expected-warning {{'__builtin_is_constant_evaluated' will always evaluate to 'true' in a manifestly constant-evaluated expression}}
return 0;
else
return 1;
}
constexpr int nowarn1() {
if (std::is_constant_evaluated())
return 0;
else
return 1;
}
constexpr int nowarn2() {
if (!__builtin_is_constant_evaluated())
return 0;
else
return 1;
}