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libcxx_old/test/std/experimental/utilities/meta/meta.detect/detected_t.pass.cpp

50 lines
1.1 KiB
C++

//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: c++98, c++03, c++11
// <experimental/type_traits>
#include <experimental/type_traits>
#include <string>
#include "test_macros.h"
namespace ex = std::experimental;
template <typename T>
using callFoo = decltype(std::declval<T&>().Foo());
struct yesFoo {
int Foo() { return 0; }
};
struct noFoo {
};
struct wrongFoo {
std::string Foo() { return ""; }
};
struct convertibleFoo {
long Foo() { return 0; }
};
template <typename T, typename Res>
void test() {
static_assert( std::is_same<Res, typename ex::detected_t<callFoo, T>>::value, "" );
}
int main(int, char**) {
test<yesFoo, int>();
test<noFoo, ex::nonesuch>(); // lookup failure returns nonesuch
test<wrongFoo, std::string>();
return 0;
}