clang-tests/gcc-4_2-testsuite/src/gcc.dg/cpp/ucnid-7.c

/* { dg-do compile } */
/* { dg-options "-std=c99 -fextended-identifiers" } */
#define a b(
#define b(x) q
int a\U0000000z ); /* { dg-warning "incomplete universal character name" } */