gcc/testsuite/gcc.dg/cpp/ucnid-5.c

/* { dg-do preprocess } */
/* { dg-options "-std=c99 -pedantic -fextended-identifiers" } */

\u00AA
\u00AB /* { dg-error "not valid in an identifier" } */
\u00B6 /* { dg-error "not valid in an identifier" } */
\u00BA
\u00C0
\u00D6
\u0384 /* { dg-error "not valid in an identifier" } */

\u0669 /* { dg-error "not valid at the start of an identifier" } */
A\u0669
0\u00BA
0\u0669
\u0E59 /* { dg-error "not valid at the start of an identifier" } */
A\u0E59