57 lines
1.9 KiB
C++
57 lines
1.9 KiB
C++
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// RUN: %clang_cc1 -std=c++11 -verify %s
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// RUN: %clang_cc1 -std=c++2a -verify %s
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struct Q { typedef int type; };
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// "The substitution occurs in all types and expressions that are used in [...]
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// template parameter declarations." In particular, we must substitute into the
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// type of a parameter pack that is not a pack expansion, even if we know the
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// corresponding argument pack is empty.
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template<typename T, typename T::type...> void a(T);
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int &a(...);
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int &a_disabled = a(0);
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int &a_enabled = a(Q()); // expected-error {{cannot bind to a temporary of type 'void'}}
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template<typename T, template<typename T::type> class ...X> void b(T);
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int &b(...);
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int &b_disabled = b(0);
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int &b_enabled = b(Q()); // expected-error {{cannot bind to a temporary of type 'void'}}
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template<typename T, template<typename T::type...> class ...X> void c(T);
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int &c(...);
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int &c_disabled = c(0);
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int &c_enabled = c(Q()); // expected-error {{cannot bind to a temporary of type 'void'}}
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// The substitution proceeds in lexical order and stops when a condition that
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// causes deduction to fail is encountered.
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#if __cplusplus > 201702L
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namespace reversed_operator_substitution_order {
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struct X { X(int); };
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struct Y { Y(int); };
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struct Cat {};
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namespace no_adl {
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Cat operator<=>(Y, X);
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bool operator<(int, Cat);
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template<typename T> struct indirect_sizeof {
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static_assert(sizeof(T) != 0);
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static const auto value = sizeof(T);
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};
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// We should substitute into the construction of the X object before the
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// construction of the Y object, so this is a SFINAE case rather than a
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// hard error. This requires substitution to proceed in lexical order
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// despite the prior rewrite to
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// 0 < (Y(...) <=> X(...))
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template<typename T> float &f(
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decltype(
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X(sizeof(T)) < Y(indirect_sizeof<T>::value)
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)
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);
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template<typename T> int &f(...);
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}
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int &r = no_adl::f<void>(true);
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float &s = no_adl::f<int>(true);
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}
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#endif
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