07a0b0ee94
Before this patch, the user needed to specialize both of `is_placeholder<MyType>` and `is_placeholder<const MyType>`. After this patch, only the former is needed (although the latter is harmless if provided). The new tests don't actually fail unless return type deduction is used, which is a C++14 feature. Specializing `is_placeholder` is still allowed in C++11, though. Fixes #51095. Differential Revision: https://reviews.llvm.org/D116388
57 lines
1.5 KiB
C++
57 lines
1.5 KiB
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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// UNSUPPORTED: c++03, c++11
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// <functional>
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// template<class T> struct is_bind_expression;
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// A program may specialize this template for a program-defined type T
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// to have a base characteristic of true_type to indicate that T should
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// be treated as a subexpression in a bind call.
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// https://llvm.org/PR51753
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#include <functional>
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#include <cassert>
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#include <type_traits>
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struct MyBind {
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int operator()(int x, int y) const { return 10*x + y; }
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};
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template<> struct std::is_bind_expression<MyBind> : std::true_type {};
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int main(int, char**)
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{
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{
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auto f = [](auto x) { return 10*x + 9; };
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MyBind bindexpr;
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auto bound = std::bind(f, bindexpr);
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assert(bound(7, 8) == 789);
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}
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{
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auto f = [](auto x) { return 10*x + 9; };
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const MyBind bindexpr;
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auto bound = std::bind(f, bindexpr);
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assert(bound(7, 8) == 789);
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}
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{
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auto f = [](auto x) { return 10*x + 9; };
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MyBind bindexpr;
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auto bound = std::bind(f, std::move(bindexpr));
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assert(bound(7, 8) == 789);
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}
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{
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auto f = [](auto x) { return 10*x + 9; };
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const MyBind bindexpr;
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auto bound = std::bind(f, std::move(bindexpr));
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assert(bound(7, 8) == 789);
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}
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return 0;
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}
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