56 lines · cpp
1//===----------------------------------------------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9// <string>10 11// UNSUPPORTED: c++03, c++11, c++14, c++17, c++2012// To silence a GCC warning-turned-error re. `BadAlloc::value_type`.13// ADDITIONAL_COMPILE_FLAGS(gcc-style-warnings): -Wno-unused-local-typedefs14 15// template<ranges::input_range R,16// class Allocator = allocator<ranges::range_value_t<R>>>17// basic_string(from_range_t, R&&, Allocator = Allocator())18// -> basic_string<ranges::range_value_t<R>, char_traits<ranges::range_value_t<R>>,19// Allocator>; // C++2320//21// The deduction guide shall not participate in overload resolution if Allocator22// is a type that does not qualify as an allocator (in addition to the `input_range` concept being satisfied by `R`).23 24#include <array>25#include <string>26 27#include "deduction_guides_sfinae_checks.h"28#include "test_allocator.h"29#include "asan_testing.h"30 31int main(int, char**) {32 using Char = char16_t;33 34 {35 std::basic_string c(std::from_range, std::array<Char, 0>());36 static_assert(std::is_same_v<decltype(c), std::basic_string<Char>>);37 LIBCPP_ASSERT(is_string_asan_correct(c));38 }39 40 {41 using Alloc = test_allocator<Char>;42 std::basic_string c(std::from_range, std::array<Char, 0>(), Alloc());43 static_assert(std::is_same_v<decltype(c), std::basic_string<Char, std::char_traits<Char>, Alloc>>);44 LIBCPP_ASSERT(is_string_asan_correct(c));45 }46 47 // Note: defining `value_type` is a workaround because one of the deduction guides will end up instantiating48 // `basic_string`, and that would fail with a hard error if the given allocator doesn't define `value_type`.49 struct BadAlloc {50 using value_type = char;51 };52 SequenceContainerDeductionGuidesSfinaeAway<std::basic_string, std::basic_string<char>, BadAlloc>();53 54 return 0;55}56