1 #if defined(CLANG) 2 #pragma clang system_header 3 // expected-no-diagnostics 4 #elif defined(GCC) 5 #pragma GCC system_header 6 // expected-no-diagnostics 7 #elif defined(MS) 8 #pragma system_header 9 // expected-no-diagnostics 10 #else 11 // expected-warning@+1{{unknown pragma ignored}} 12 #pragma system_header 13 14 // expected-note@+4{{previous definition is here}} 15 // expected-warning@+4{{redefinition of typedef 'x' is a C11 feature}} 16 #endif 17 18 typedef int x; 19 typedef int x; 20