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// RUN: %clang_cc1 -std=c++2a -x c++ %s -verify
template<typename T, typename U=void>
concept C = true;
namespace ns {
template<typename T, typename U=void>
concept D = true;
}
int foo() {
int I;
{ns::D auto a = 1;}
{C auto a = 1;}
{C<> auto a = 1;}
{C<int> auto a = 1;}
{ns::D<int> auto a = 1;}
{const ns::D auto &a = 1;}
{const C auto &a = 1;}
{const C<> auto &a = 1;}
{const C<int> auto &a = 1;}
{const ns::D<int> auto &a = 1;}
{C decltype(auto) a = 1;}
{C<> decltype(auto) a = 1;}
{C<int> decltype(auto) a = 1;}
{const C<> decltype(auto) &a = 1;} // expected-error{{'decltype(auto)' cannot be combined with other type specifiers}}
// expected-error@-1{{cannot form reference to 'decltype(auto)'}}
{const C<int> decltype(auto) &a = 1;} // expected-error{{'decltype(auto)' cannot be combined with other type specifiers}}
// expected-error@-1{{cannot form reference to 'decltype(auto)'}}
{C a = 1;}
// expected-error@-1{{expected 'auto' or 'decltype(auto)' after concept name}}
{C const a2 = 1;}
// expected-error@-1{{expected 'auto' or 'decltype(auto)' after concept name}}
{C &a3 = I;}
// expected-error@-1{{expected 'auto' or 'decltype(auto)' after concept name}}
{C &&a4 = 1;}
// expected-error@-1{{expected 'auto' or 'decltype(auto)' after concept name}}
{C decltype a19 = 1;}
// expected-error@-1{{expected '('}}
{C decltype(1) a20 = 1;}
// expected-error@-1{{expected 'auto' or 'decltype(auto)' after concept name}}
}
void foo1(C auto &a){}
void foo2(C const &a){}
// expected-error@-1{{expected 'auto' or 'decltype(auto)' after concept name}}
void foo3(C auto const &a){}
void foo4(const C &a){}
// expected-error@-1{{expected 'auto' or 'decltype(auto)' after concept name}}
namespace non_type {
template<int v>
concept C1 = true;
auto f() -> C1 auto {} // expected-error{{concept named in type constraint is not a type concept}}
auto g(C1 auto); // expected-error{{concept named in type constraint is not a type concept}}
C1 auto a = 0; // expected-error{{concept named in type constraint is not a type concept}}
C1 decltype(auto) b = 0; // expected-error{{concept named in type constraint is not a type concept}}
}
namespace arity {
template<typename v, typename>
concept C1 = true;
auto f() -> C1 auto {} // expected-error{{'C1' requires more than 1 template argument; provide the remaining arguments explicitly to use it here}}
auto g(C1 auto); // expected-error{{'C1' requires more than 1 template argument; provide the remaining arguments explicitly to use it here}}
C1 auto a = 0; // expected-error{{'C1' requires more than 1 template argument; provide the remaining arguments explicitly to use it here}}
C1 decltype(auto) b = 0; // expected-error{{'C1' requires more than 1 template argument; provide the remaining arguments explicitly to use it here}}
}
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