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[libc] add invoke_result type traits
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‎libc/src/__support/CPP/type_traits.h

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#include "src/__support/CPP/type_traits/enable_if.h"
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#include "src/__support/CPP/type_traits/false_type.h"
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#include "src/__support/CPP/type_traits/integral_constant.h"
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#include "src/__support/CPP/type_traits/invoke_result.h"
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#include "src/__support/CPP/type_traits/is_arithmetic.h"
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#include "src/__support/CPP/type_traits/is_array.h"
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#include "src/__support/CPP/type_traits/is_base_of.h"

‎libc/src/__support/CPP/type_traits/invoke_result.h

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//===-- invoke_result type_traits -------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_LIBC_SRC_SUPPORT_CPP_TYPE_TRAITS_INVOKE_RESULT_H
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#define LLVM_LIBC_SRC_SUPPORT_CPP_TYPE_TRAITS_INVOKE_RESULT_H
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#include "src/__support/CPP/type_traits/decay.h"
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#include "src/__support/CPP/type_traits/enable_if.h"
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#include "src/__support/CPP/type_traits/false_type.h"
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#include "src/__support/CPP/type_traits/is_base_of.h"
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#include "src/__support/CPP/type_traits/is_function.h"
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#include "src/__support/CPP/type_traits/true_type.h"
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#include "src/__support/CPP/utility/declval.h"
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#include "src/__support/CPP/utility/forward.h"
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// BEWARE : this implementation is not fully conformant as it doesn't take
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// `cpp::reference_wrapper` into account.
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namespace __llvm_libc::cpp {
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// invoke_result
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namespace detail {
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template <class T> struct is_reference_wrapper : cpp::false_type {};
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// Disable specialization on `cpp::reference_wrapper` as it is not yet
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// implemented.
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// template <class U> struct
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// is_reference_wrapper<cpp::reference_wrapper<U>> : cpp::true_type {};
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template <class T> struct invoke_impl {
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template <class F, class... Args>
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static auto call(F &&f, Args &&...args)
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-> decltype(cpp::forward<F>(f)(cpp::forward<Args>(args)...));
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};
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template <class B, class MT> struct invoke_impl<MT B::*> {
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template <class T, class Td = cpp::decay_t<T>,
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class = cpp::enable_if_t<cpp::is_base_of_v<B, Td>>>
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static auto get(T &&t) -> T &&;
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template <class T, class Td = cpp::decay_t<T>,
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class = cpp::enable_if_t<is_reference_wrapper<Td>::value>>
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static auto get(T &&t) -> decltype(t.get());
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template <class T, class Td = cpp::decay_t<T>,
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class = cpp::enable_if_t<!cpp::is_base_of_v<B, Td>>,
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class = cpp::enable_if_t<!is_reference_wrapper<Td>::value>>
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static auto get(T &&t) -> decltype(*cpp::forward<T>(t));
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template <class T, class... Args, class MT1,
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class = cpp::enable_if_t<cpp::is_function_v<MT1>>>
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static auto call(MT1 B::*pmf, T &&t, Args &&...args)
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-> decltype((invoke_impl::get(cpp::forward<T>(t)).*
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pmf)(cpp::forward<Args>(args)...));
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template <class T>
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static auto call(MT B::*pmd, T &&t)
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-> decltype(invoke_impl::get(cpp::forward<T>(t)).*pmd);
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};
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template <class F, class... Args, class Fd = typename cpp::decay_t<F>>
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auto INVOKE(F &&f, Args &&...args)
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-> decltype(invoke_impl<Fd>::call(cpp::forward<F>(f),
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cpp::forward<Args>(args)...));
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template <typename AlwaysVoid, typename, typename...> struct invoke_result {};
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template <typename F, typename... Args>
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struct invoke_result<decltype(void(detail::INVOKE(cpp::declval<F>(),
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cpp::declval<Args>()...))),
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F, Args...> {
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using type =
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decltype(detail::INVOKE(cpp::declval<F>(), cpp::declval<Args>()...));
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};
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} // namespace detail
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template <class F, class... ArgTypes>
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struct invoke_result : detail::invoke_result<void, F, ArgTypes...> {};
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template <class F, class... ArgTypes>
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using invoke_result_t = typename invoke_result<F, ArgTypes...>::type;
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} // namespace __llvm_libc::cpp
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#endif // LLVM_LIBC_SRC_SUPPORT_CPP_TYPE_TRAITS_INVOKE_RESULT_H

‎utils/bazel/llvm-project-overlay/libc/BUILD.bazel

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@@ -295,6 +295,7 @@ libc_support_library(
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"src/__support/CPP/type_traits/enable_if.h",
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"src/__support/CPP/type_traits/false_type.h",
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"src/__support/CPP/type_traits/integral_constant.h",
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"src/__support/CPP/type_traits/invoke_result.h",
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"src/__support/CPP/type_traits/is_arithmetic.h",
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"src/__support/CPP/type_traits/is_array.h",
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"src/__support/CPP/type_traits/is_base_of.h",
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"src/__support/CPP/type_traits/type_identity.h",
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"src/__support/CPP/type_traits/void_t.h",
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"src/__support/CPP/utility/declval.h",
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"src/__support/CPP/utility/forward.h",
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],
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deps = [
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":__support_macros_attributes",

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