https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62086
Bug ID: 62086 Summary: A bug with option -fextended-identifiers Product: gcc Version: 4.9.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: preprocessor Assignee: unassigned at gcc dot gnu.org Reporter: pangbw at gmail dot com For this simple code, it would compile without -fextended-identifiers but fail with it: $cat ~/x.c int main() { #if 0 int \u00A8\u00AA\u00AD\u00AF\u00B2\u00B5 = 7; #endif } $ gcc -c ~/x.c $ gcc -c -fextended-identifiers ~/x.c x.c: In function ‘main’: x.c:4:7: warning: universal character names are only valid in C++ and C99 [enabled by default] x.c:4:7: error: universal character \u00A8 is not valid in an identifier x.c:4:7: warning: universal character names are only valid in C++ and C99 [enabled by default] x.c:4:7: warning: universal character names are only valid in C++ and C99 [enabled by default] x.c:4:7: error: universal character \u00AD is not valid in an identifier x.c:4:7: warning: universal character names are only valid in C++ and C99 [enabled by default] x.c:4:7: error: universal character \u00AF is not valid in an identifier x.c:4:7: warning: universal character names are only valid in C++ and C99 [enabled by default] x.c:4:7: error: universal character \u00B2 is not valid in an identifier x.c:4:7: warning: universal character names are only valid in C++ and C99 [enabled by default]