1*a042fcbeSHaojian Wu // RUN: %clang_cc1 -std=c++20 -Wfatal-errors -verify %s 2*a042fcbeSHaojian Wu 3*a042fcbeSHaojian Wu template <typename> int a; 4*a042fcbeSHaojian Wu template <typename... b> concept c = a<b...>; 5*a042fcbeSHaojian Wu template <typename> concept e = c<>; 6*a042fcbeSHaojian Wu 7*a042fcbeSHaojian Wu // must be a fatal error to trigger the crash 8*a042fcbeSHaojian Wu undefined; // expected-error {{a type specifier is required for all declarations}} 9*a042fcbeSHaojian Wu 10*a042fcbeSHaojian Wu template <typename d> concept g = e<d>; 11*a042fcbeSHaojian Wu template <g> struct h 12*a042fcbeSHaojian Wu template <g d> 13*a042fcbeSHaojian Wu struct h<d>; 14