|  | // RUN: %clang_cc1 -std=c++2a -emit-pch %s -o %t | 
|  | // RUN: %clang_cc1 -std=c++2a -include-pch %t -verify %s | 
|  |  | 
|  | // RUN: %clang_cc1 -std=c++2a -emit-pch -fpch-instantiate-templates %s -o %t | 
|  | // RUN: %clang_cc1 -std=c++2a -include-pch %t -verify %s | 
|  |  | 
|  | // expected-no-diagnostics | 
|  |  | 
|  | #ifndef HEADER | 
|  | #define HEADER | 
|  |  | 
|  | template<typename... T> | 
|  | concept C = true; | 
|  |  | 
|  | namespace n { | 
|  | template<typename... T> | 
|  | concept C = true; | 
|  | } | 
|  |  | 
|  | void f() { | 
|  | (void)C<int>; | 
|  | (void)C<int, void>; | 
|  | (void)n::C<void>; | 
|  | } | 
|  |  | 
|  | #else /*included pch*/ | 
|  |  | 
|  | int main() { | 
|  | (void)C<int>; | 
|  | (void)C<int, void>; | 
|  | (void)n::C<void>; | 
|  | f(); | 
|  | } | 
|  |  | 
|  | #endif // HEADER |