diff options
| author |  Abseil Team <absl-team@google.com> | 2020-11-20 09:52:55 -0800 |
|---|---|---|
| committer |  Derek Mauro <dmauro@google.com> | 2020-11-20 13:05:26 -0500 |
| commit | e19260fd7dbef881492fd73891e0be5bd4a09b95 (patch) | |
| tree | e83b1fda901b1a079b6a22330d9b775b87369c87 /absl/meta | |
| parent | 4fd9a1ec5077daac14eeee05df931d658ec0b7b8 (diff) | |
Export of internal Abseil changes
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1f91ba7fcb79244fce1fe448c1d31fb5b0580584 by Derek Mauro <dmauro@google.com>:
Internal change
PiperOrigin-RevId: 343511158
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8dcd61fed44f4e56044aa4a899cc3124117fa21f by Abseil Team <absl-team@google.com>:
refactors result_of so it doesn't unnecessarily break in C++20 mode
std::result_of was deprecated in C++17 and removed in C++20. This CL
adds an implementation detail so it transparently continues to work
when external users turn up to C++20 or later.
The implementation is derived from C++17's specification of result_of
[depr.meta.types][1].
[1]: https://timsong-cpp.github.io/cppwp/n4659/depr.meta.types
Fixes #649
PiperOrigin-RevId: 343395432
GitOrigin-RevId: 1f91ba7fcb79244fce1fe448c1d31fb5b0580584
Change-Id: Id5d9c55dc7547737bade48a15f2f5740f414d811
Diffstat (limited to 'absl/meta')
| -rw-r--r-- | absl/meta/type_traits.h | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/absl/meta/type_traits.h b/absl/meta/type_traits.h index 75689bb6..d5cb5f3b 100644 --- a/absl/meta/type_traits.h +++ b/absl/meta/type_traits.h @@ -610,8 +610,22 @@ using common_type_t = typename std::common_type<T...>::type; template <typename T> using underlying_type_t = typename std::underlying_type<T>::type; -template <typename T> -using result_of_t = typename std::result_of<T>::type; + +namespace type_traits_internal { + +#if __cplusplus >= 201703L +// std::result_of is deprecated (C++17) or removed (C++20) +template<typename> struct result_of; +template<typename F, typename... Args> +struct result_of<F(Args...)> : std::invoke_result<F, Args...> {}; +#else +template<typename F> using result_of = std::result_of<F>; +#endif + +} // namespace type_traits_internal + +template<typename F> +using result_of_t = typename type_traits_internal::result_of<F>::type; namespace type_traits_internal { // In MSVC we can't probe std::hash or stdext::hash because it triggers a |