llvm/clang/test/SemaObjCXX/Inputs/nullability-consistency-system/nullability-consistency-system.h

// Simply marking this as "#pragma clang system_header" didn't tickle the bug

void system1(int *ptr);
#if WARN_IN_SYSTEM_HEADERS
// expected-warning@-2{{pointer is missing a nullability type specifier}}
// expected-note@-3 {{insert '_Nullable' if the pointer may be null}}
// expected-note@-4 {{insert '_Nonnull' if the pointer should never be null}}
#endif

void system2(int * _Nonnull);