This is a copy of a bug report from Red Hat's bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=449191
The bug is that with mapped locations, the code in check_empty_body does not notice that the while() from the macro expansion violates the rule. This is because of the hack we needed to get decent error messages with mapped locations -- tokens resulting from a macro expansion are all given the location of the start of the expansion. Steps to Reproduce: 1. compile example program: > cat warn2.cc int main(int, char**) { #define XXX while(0); XXX ; while (0); } > g++ -W -Werror -c warn2.cc Actual results: cc1plus: warnings being treated as errors warn2.cc: In function int main(int, char**): warn2.cc:6: error: suggest a space before ; or explicit braces around empty body in while statement Expected results: warn2.cc: In function int main(int, char**): warn2.cc:5: warning: suggest a space before ; or explicit braces around empty body in while statement warn2.cc:6: warning: suggest a space before ; or explicit braces around empty body in while statement -- Summary: [4.3/4.4 regression] warning not emitted when code expanded from macro Product: gcc Version: 4.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: tromey at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36478