33 lines
964 B
C++
33 lines
964 B
C++
// RUN: %clang_cc1 -fsyntax-only %s -std=c++11 -verify
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// This is a test for an egregious hack in Clang that works around
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// an issue with GCC's <type_traits> implementation. std::common_type
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// relies on pre-standard rules for decltype(), in which it doesn't
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// produce reference types so frequently.
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#ifdef BE_THE_HEADER
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#pragma GCC system_header
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namespace std {
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template<typename T> T &&declval();
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template<typename...Ts> struct common_type {};
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template<typename A, typename B> struct common_type<A, B> {
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// Under the rules in the standard, this always produces a
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// reference type.
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typedef decltype(true ? declval<A>() : declval<B>()) type;
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};
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}
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#else
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#define BE_THE_HEADER
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#include "libstdcxx_common_type_hack.cpp"
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using T = int;
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using T = std::common_type<int, int>::type;
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using U = int; // expected-note {{here}}
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using U = decltype(true ? std::declval<int>() : std::declval<int>()); // expected-error {{different types}}
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#endif
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