[PATCH v24 33/33] libstdc++: Optimize std::is_invocable compilation performance

[Patrick Palka]

On Fri, Oct 20, 2023 at 12:22 PM Ken Matsui <kmatsui@gcc.gnu.org> wrote:
>
> This patch optimizes the compilation performance of std::is_invocable
> by dispatching to the new __is_invocable built-in trait.
>
> libstdc++-v3/ChangeLog:
>
>         * include/std/type_traits (is_invocable): Use __is_invocable
>         built-in trait.

Nice!  We should use the trait directly in is_invocable_v too.

>         * testsuite/20_util/is_invocable/incomplete_args_neg.cc: Handle
>         the new error from __is_invocable.
>         * testsuite/20_util/is_invocable/incomplete_neg.cc: Likewise.
>
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> ---
>  libstdc++-v3/include/std/type_traits                        | 6 ++++++
>  .../testsuite/20_util/is_invocable/incomplete_args_neg.cc   | 1 +
>  .../testsuite/20_util/is_invocable/incomplete_neg.cc        | 1 +
>  3 files changed, 8 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> index 75a94cb8d7e..91851b78c7e 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -3167,9 +3167,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      using invoke_result_t = typename invoke_result<_Fn, _Args...>::type;
>
>    /// std::is_invocable
> +#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_invocable)
> +  template<typename _Fn, typename... _ArgTypes>
> +    struct is_invocable
> +    : public __bool_constant<__is_invocable(_Fn, _ArgTypes...)>
> +#else
>    template<typename _Fn, typename... _ArgTypes>
>      struct is_invocable
>      : __is_invocable_impl<__invoke_result<_Fn, _ArgTypes...>, void>::type
> +#endif
>      {
>        static_assert(std::__is_complete_or_unbounded(__type_identity<_Fn>{}),
>         "_Fn must be a complete class or an unbounded array");
> diff --git a/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_args_neg.cc b/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_args_neg.cc
> index 34d1d9431d1..3f9e5274f3c 100644
> --- a/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_args_neg.cc
> +++ b/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_args_neg.cc
> @@ -18,6 +18,7 @@
>  // <http://www.gnu.org/licenses/>.
>
>  // { dg-error "must be a complete class" "" { target *-*-* } 0 }
> +// { dg-prune-output "invalid use of incomplete type" }
>
>  #include <type_traits>
>
> diff --git a/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_neg.cc b/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_neg.cc
> index e1e54d25ee5..92af48c48b6 100644
> --- a/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_neg.cc
> +++ b/libstdc++-v3/testsuite/20_util/is_invocable/incomplete_neg.cc
> @@ -18,6 +18,7 @@
>  // <http://www.gnu.org/licenses/>.
>
>  // { dg-error "must be a complete class" "" { target *-*-* } 0 }
> +// { dg-prune-output "invalid use of incomplete type" }
>
>  #include <type_traits>
>
> --
> 2.42.0
>