1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 // UNSUPPORTED: c++98, c++03, c++11, c++14, c++17
10 
11 // <type_traits>
12 
13 // constexpr bool is_constant_evaluated() noexcept; // C++20
14 
15 #include <type_traits>
16 #include <cassert>
17 
18 #include "test_macros.h"
19 
20 #ifndef __cpp_lib_is_constant_evaluated
21 #if TEST_HAS_BUILTIN(__builtin_is_constant_evaluated)
22 # error __cpp_lib_is_constant_evaluated should be defined
23 #endif
24 #endif
25 
26 template <bool> struct InTemplate {};
27 
28 int main(int, char**)
29 {
30 #ifdef __cpp_lib_is_constant_evaluated
31   // Test the signature
32   {
33     ASSERT_SAME_TYPE(decltype(std::is_constant_evaluated()), bool);
34     ASSERT_NOEXCEPT(std::is_constant_evaluated());
35     constexpr bool p = std::is_constant_evaluated();
36     assert(p);
37   }
38   // Test the return value of the builtin for basic sanity only. It's the
39   // compilers job to test tho builtin for correctness.
40   {
41     static_assert(std::is_constant_evaluated(), "");
42     bool p = std::is_constant_evaluated();
43     assert(!p);
44     ASSERT_SAME_TYPE(InTemplate<std::is_constant_evaluated()>, InTemplate<true>);
45     static int local_static = std::is_constant_evaluated() ? 42 : -1;
46     assert(local_static == 42);
47   }
48 #endif
49   return 0;
50 }
51