f72b3e1c07
Adds explanation why `is_constructible` evaluates to false. This reapplies as-is e476f968bc8e438a0435d10934f148de570db8eb. This was reverted in 16d5db71b3c38f21aa17783a8758f947dca5883f because of a test failure in libc++. The test failure in libc++ is interesting in that, in the absence of nested diagnostics a bunch of diagnostics are emitted as error instead of notes, which we cannot silence with `-verify-ignore-unexpected`. The fix here is to prevent the diagnostics to be emitted in the first place. However this is clearly not ideal and we should make sure to deploy a better solution in the clang 22 time frame, in the lines of https://discourse.llvm.org/t/rfc-add-a-new-text-diagnostics-format-that-supports-nested-diagnostics/87641/12 Fixes #150601 --------- Co-authored-by: Shamshura Egor <164661612+egorshamshura@users.noreply.github.com>
47 lines
1.4 KiB
C++
47 lines
1.4 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, c++14, c++17
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// functional
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// template <class F, class... Args>
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// constexpr unspecified bind_front(F&&, Args&&...);
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#include <functional>
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constexpr int pass(const int n) { return n; }
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int simple(int n) { return n; }
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template<class T>
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T do_nothing(T t) { return t; }
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struct NotMoveConst
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{
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NotMoveConst(NotMoveConst &&) = delete;
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NotMoveConst(NotMoveConst const&) = delete;
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NotMoveConst(int) { }
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};
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void testNotMoveConst(NotMoveConst) { }
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void f() {
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int n = 1;
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const int c = 1;
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auto p = std::bind_front(pass, c);
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static_assert(p() == 1); // expected-error {{static assertion expression is not an integral constant expression}}
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auto d = std::bind_front(do_nothing, n); // expected-error {{no matching function for call to 'bind_front'}}
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auto t = std::bind_front(testNotMoveConst, NotMoveConst(0)); // expected-error {{no matching function for call to 'bind_front'}}
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// expected-error@*:* 0-1{{call to deleted constructor of 'NotMoveConst'}}
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}
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