1 // PR c++/48468 2 // { dg-do compile { target c++11 } } 3 // { dg-prune-output "note" } 4 5 template<class T> 6 T&& declval() noexcept; 7 8 template< class T > f1(T & x)9inline void f1( T& x ) noexcept( noexcept( declval<T&>().foo() ) ) // { dg-error "Z" } 10 { 11 x.foo(); 12 } 13 14 template< class T, 15 bool Noexcept = noexcept( declval<T&>().foo() ) // { dg-error "no member|not convert" } 16 17 > f2(T & x)18inline void f2( T& x ) noexcept( Noexcept ) 19 { 20 x.foo(); 21 } 22 23 // a common and trivial mistake 24 template< class T > f3(T & x)25inline void f3( T& x ) noexcept( declval<T&>().foo() ) // { dg-error "Z" } 26 { 27 x.foo(); 28 } 29 30 struct X 31 { 32 void foo(); 33 }; 34 35 struct Y 36 { 37 void foo() noexcept; 38 }; 39 40 struct Z {}; 41 main()42int main() 43 { 44 X x; Y y; Z z; 45 46 static_assert( !noexcept( f1(x) ), "OK." ); 47 static_assert( !noexcept( f2(x) ), "OK." ); 48 // static_assert( !noexcept( f3(x) ), "shall be ill-formed(OK)." ); 49 50 static_assert( noexcept( f1(y) ), "OK." ); 51 static_assert( noexcept( f2(y) ), "OK." ); 52 // static_assert( noexcept( f3(y) ), "shall be ill-formed(OK)." ); 53 54 noexcept( f1(z) ); // { dg-message "required" } 55 static_assert( noexcept( f2(z) ), "shall be ill-formed." ); // { dg-error "no match" } 56 noexcept( f3(z) ); // { dg-message "required" } 57 } 58