diff options
author | Marshall Clow <mclow.lists@gmail.com> | 2019-07-01 23:16:46 +0000 |
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committer | Marshall Clow <mclow.lists@gmail.com> | 2019-07-01 23:16:46 +0000 |
commit | e380104a4398587d8863855b05b4640fef025699 (patch) | |
tree | 10bd4e3451ff3bd461cab0f4f40c80838efcef04 | |
parent | 268aced50d7ebb097da2775cf69379397ee006ea (diff) |
Add a private call '__libcpp_is_constant_evaluated' which 'works' for old language versions and w/o any compiler support. 'Working', in this case, means that it returns false in those cases.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@364873 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r-- | include/type_traits | 7 | ||||
-rw-r--r-- | test/libcxx/type_traits/is_constant_evaluated.pass.cpp | 34 |
2 files changed, 40 insertions, 1 deletions
diff --git a/include/type_traits b/include/type_traits index 3b09c5962..c7e474925 100644 --- a/include/type_traits +++ b/include/type_traits @@ -3999,13 +3999,18 @@ enum class endian }; #endif -#if _LIBCPP_STD_VER > 17 && !defined(_LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED) +#ifndef _LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED +#if _LIBCPP_STD_VER > 17 _LIBCPP_INLINE_VISIBILITY inline constexpr bool is_constant_evaluated() noexcept { return __builtin_is_constant_evaluated(); } #endif +_LIBCPP_CONSTEXPR bool __libcpp_is_constant_evaluated() _NOEXCEPT { return __builtin_is_constant_evaluated(); } +#else +_LIBCPP_CONSTEXPR bool __libcpp_is_constant_evaluated() _NOEXCEPT { return false; } +#endif template <class _CharT> using _IsCharLikeType = _And<is_standard_layout<_CharT>, is_trivial<_CharT> >; diff --git a/test/libcxx/type_traits/is_constant_evaluated.pass.cpp b/test/libcxx/type_traits/is_constant_evaluated.pass.cpp new file mode 100644 index 000000000..157d913cc --- /dev/null +++ b/test/libcxx/type_traits/is_constant_evaluated.pass.cpp @@ -0,0 +1,34 @@ +//===----------------------------------------------------------------------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// + +// <type_traits> + +// __libcpp_is_constant_evaluated() + +// returns false when there's no constant evaluation support from the compiler. +// as well as when called not in a constexpr context + +#include <type_traits> +#include <cassert> + +#include "test_macros.h" + +int main (int, char**) { + ASSERT_SAME_TYPE(decltype(std::__libcpp_is_constant_evaluated()), bool); + ASSERT_NOEXCEPT(std::__libcpp_is_constant_evaluated()); + +#if !defined(_LIBCPP_HAS_NO_BUILTIN_IS_CONSTANT_EVALUATED) && !defined(_LIBCPP_CXX03_LANG) + static_assert(std::__libcpp_is_constant_evaluated(), ""); +#endif + + bool p = std::__libcpp_is_constant_evaluated(); + assert(!p); + + return 0; + } |