2 // { dg-do compile { target c++20 } }
8 concept C0 = requires (auto x) { // { dg-error "placeholder type" }
13 concept C1 = requires (C1 auto x) { // { dg-error "not been declared|placeholder|two or more|in requirements" }
14 x; // { dg-error "not declared" }
15 { x } -> c; // { dg-message "is invalid|not declared" }
23 f(1); // { dg-error "" }