llvm-project/clang/test/Preprocessor/user_defined_system_framework.c

// RUN: %clang_cc1 -fsyntax-only -F %S/Inputs -Wsign-conversion -verify %s
// expected-no-diagnostics

// Check that TestFramework is treated as a system header.
#include <TestFramework/TestFramework.h>

int f1() {
  return test_framework_func(1) + another_test_framework_func(2);
}