llvm-project/clang/test/Sema/c89.c

/* RUN: clang %s -std=c89 -pedantic -parse-ast-check
 */
void foo() {
  {
    int i;
    i = i + 1;
    int j;          /* expected-warning {{mixing declarations and code}} */
  }
  {
    __extension__ int i;
    i = i + 1;
    int j;          /* expected-warning {{mixing declarations and code}} */
  }
  {
    int i;
    i = i + 1;
    __extension__ int j; /* expected-warning {{mixing declarations and code}} */
  }
}