| 1 | //===----------------------------------------------------------------------===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | // UNSUPPORTED: c++03, c++11, c++14 |
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| 10 | |
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| 11 | // <variant> |
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| 12 | |
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| 13 | // template <class ...Types> class variant; |
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| 14 | |
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| 15 | // Make sure that the implicitly-generated CTAD works. |
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| 16 | |
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| 17 | // We make sure that it is not ill-formed, however we still produce a warning for |
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| 18 | // this one because explicit construction from a variant using CTAD is ambiguous |
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| 19 | // (in the sense that the programmer intent is not clear). |
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| 20 | // ADDITIONAL_COMPILE_FLAGS(gcc-style-warnings): -Wno-ctad-maybe-unsupported |
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| 21 | |
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| 22 | #include <variant> |
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| 23 | |
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| 24 | #include "test_macros.h" |
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| 25 | |
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| 26 | int main(int, char**) { |
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| 27 | // This is the motivating example from P0739R0 |
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| 28 | { |
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| 29 | std::variant<int, double> v1(3); |
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| 30 | std::variant v2 = v1; |
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| 31 | ASSERT_SAME_TYPE(decltype(v2), std::variant<int, double>); |
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| 32 | } |
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| 33 | |
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| 34 | { |
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| 35 | std::variant<int, double> v1(3); |
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| 36 | std::variant v2 = std::variant(v1); // Technically valid, but intent is ambiguous! |
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| 37 | ASSERT_SAME_TYPE(decltype(v2), std::variant<int, double>); |
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| 38 | } |
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| 39 | |
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| 40 | return 0; |
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| 41 | } |
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| 42 | |
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