1 // RUN: %clang_cc1 -std=c++20 -Wfatal-errors -verify %s 2 3 template <typename> int a; 4 template <typename... b> concept c = a<b...>; 5 template <typename> concept e = c<>; 6 7 // must be a fatal error to trigger the crash 8 undefined; // expected-error {{a type specifier is required for all declarations}} 9 10 template <typename d> concept g = e<d>; 11 template <g> struct h 12 template <g d> 13 struct h<d>; 14