http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51437
Bug #: 51437 Summary: GCC should warn on the use of reserved identifier/macro names Classification: Unclassified Product: gcc Version: unknown Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: c AssignedTo: unassig...@gcc.gnu.org ReportedBy: vanboxem.ru...@gmail.com For C and C++, Clang should warn when user code uses identifiers or macros that are implementation-reserved. For C(99), this would mean names starting with an underscore followed by another unerscore or capitalized letter. For C++ a single underscore is also reserved for the global namespace. I could have messed the above rules up, but these are the cause of a lot of unexpected bugs, and a warning would be super-easy to implement.