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[libc] add invoke / invoke_result type traits
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‎libc/src/__support/CPP/CMakeLists.txt

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@@ -104,6 +104,8 @@ add_header_library(
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type_traits/enable_if.h
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type_traits/false_type.h
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type_traits/integral_constant.h
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type_traits/invoke.h
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type_traits/invoke_result.h
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type_traits/is_arithmetic.h
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type_traits/is_array.h
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type_traits/is_base_of.h

‎libc/src/__support/CPP/type_traits.h

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@@ -18,6 +18,8 @@
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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.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.h

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//===-- invoke 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_H
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#define LLVM_LIBC_SRC_SUPPORT_CPP_TYPE_TRAITS_INVOKE_H
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#include "src/__support/CPP/type_traits/decay.h"
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#include "src/__support/CPP/type_traits/is_base_of.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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namespace detail {
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// Catch all function types.
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template <class FunctionPtrType> struct invoke_dispatcher {
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template <class... Args>
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static auto call(FunctionPtrType &&fun, Args &&...args) {
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return cpp::forward<FunctionPtrType>(fun)(cpp::forward<Args>(args)...);
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}
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};
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// Catch pointer to member function types.
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template <class Class, class FunctionReturnType>
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struct invoke_dispatcher<FunctionReturnType Class::*> {
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using FunctionPtrType = FunctionReturnType Class::*;
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template <class T, class... Args, class DecayT = cpp::decay_t<T>>
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static auto call(FunctionPtrType fun, T &&t1, Args &&...args) {
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if constexpr (cpp::is_base_of_v<Class, DecayT>) {
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// T is a (possibly cv ref) type.
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return (cpp::forward<T>(t1).*fun)(cpp::forward<Args>(args)...);
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} else {
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// T is assumed to be a pointer type.
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return (*cpp::forward<T>(t1).*fun)(cpp::forward<Args>(args)...);
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}
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}
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};
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} // namespace detail
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template <class Function, class... Args>
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auto invoke(Function &&fun, Args &&...args) {
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return detail::invoke_dispatcher<cpp::decay_t<Function>>::call(
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cpp::forward<Function>(fun), cpp::forward<Args>(args)...);
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}
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} // namespace __llvm_libc::cpp
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#endif // LLVM_LIBC_SRC_SUPPORT_CPP_TYPE_TRAITS_INVOKE_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/invoke.h"
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#include "src/__support/CPP/utility/declval.h"
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namespace __llvm_libc::cpp {
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template <class F, class... Args> struct invoke_result {
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using type =
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decltype(cpp::invoke(cpp::declval<F>(), cpp::declval<Args>()...));
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};
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template <class F, class... Args>
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using invoke_result_t = typename invoke_result<F, Args...>::type;
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} // namespace __llvm_libc::cpp
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#endif // LLVM_LIBC_SRC_SUPPORT_CPP_TYPE_TRAITS_INVOKE_RESULT_H

‎libc/test/src/__support/CPP/type_traits_test.cpp

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@@ -145,6 +145,92 @@ TEST(LlvmLibcTypeTraitsTest, integral_constant) {
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EXPECT_EQ((integral_constant<int, 4>::value), 4);
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}
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namespace invoke_detail {
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enum State { INIT = 0, A_APPLY_CALLED, B_APPLY_CALLED };
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struct A {
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State state = INIT;
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virtual ~A() {}
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virtual void apply() { state = A_APPLY_CALLED; }
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};
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struct B : public A {
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virtual ~B() {}
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virtual void apply() { state = B_APPLY_CALLED; }
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};
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void free_function() {}
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int free_function_return_5() { return 5; }
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int free_function_passtrough(int value) { return value; }
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struct Delegate {
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int (*ptr)(int) = &free_function_passtrough;
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};
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} // namespace invoke_detail
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TEST(LlvmLibcTypeTraitsTest, invoke) {
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using namespace invoke_detail;
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{ // member function call
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A a;
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EXPECT_EQ(a.state, INIT);
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cpp::invoke(&A::apply, a);
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EXPECT_EQ(a.state, A_APPLY_CALLED);
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}
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{ // overriden member function call
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B b;
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EXPECT_EQ(b.state, INIT);
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cpp::invoke(&A::apply, b);
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EXPECT_EQ(b.state, B_APPLY_CALLED);
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}
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{ // free function
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cpp::invoke(&free_function);
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EXPECT_EQ(cpp::invoke(&free_function_return_5), 5);
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EXPECT_EQ(cpp::invoke(&free_function_passtrough, 1), 1);
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}
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{ // pointer member function call
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Delegate d;
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EXPECT_EQ(cpp::invoke(&Delegate::ptr, d, 2), 2);
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}
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{ // lambda
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EXPECT_EQ(cpp::invoke([]() -> int { return 2; }), 2);
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EXPECT_EQ(cpp::invoke([](int value) -> int { return value; }, 1), 1);
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}
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}
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TEST(LlvmLibcTypeTraitsTest, invoke_result) {
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using namespace invoke_detail;
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EXPECT_TRUE(
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(cpp::is_same_v<cpp::invoke_result_t<decltype(&A::apply), A>, void>));
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EXPECT_TRUE(
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(cpp::is_same_v<cpp::invoke_result_t<decltype(&A::apply), B>, void>));
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EXPECT_TRUE(
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(cpp::is_same_v<cpp::invoke_result_t<decltype(&free_function)>, void>));
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EXPECT_TRUE(
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(cpp::is_same_v<cpp::invoke_result_t<decltype(&free_function_return_5)>,
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int>));
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EXPECT_TRUE((cpp::is_same_v<
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cpp::invoke_result_t<decltype(&free_function_passtrough), int>,
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int>));
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EXPECT_TRUE(
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(cpp::is_same_v<
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cpp::invoke_result_t<decltype(&Delegate::ptr), Delegate, int>, int>));
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{
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auto lambda = []() {};
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EXPECT_TRUE((cpp::is_same_v<cpp::invoke_result_t<decltype(lambda)>, void>));
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}
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{
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auto lambda = []() { return 0; };
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EXPECT_TRUE((cpp::is_same_v<cpp::invoke_result_t<decltype(lambda)>, int>));
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}
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{
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auto lambda = [](int) -> double { return 0; };
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EXPECT_TRUE(
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(cpp::is_same_v<cpp::invoke_result_t<decltype(lambda), int>, double>));
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}
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}
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using IntegralAndFloatingTypes =
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testing::TypeList<bool, char, short, int, long, long long, unsigned char,
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unsigned short, unsigned int, unsigned long,

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

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@@ -295,6 +295,8 @@ 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.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",
@@ -333,6 +335,7 @@ libc_support_library(
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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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