https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92668
Bug ID: 92668 Summary: -Wtautological-compare warns for macros that expand to the same symbol Product: gcc Version: 10.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: msebor at gcc dot gnu.org Target Milestone: --- Unlike the C++ front-end and unlike Clang, the C front-end issues -Wtautological-compare for comparisons involving distinct macros that expand to the same symbol. GCC should be consistent with itself, and what Clang does seems reasonable, so probably also with it. $ cat t.c && gcc -S -Wall -Wextra -Wtautological-compare t.c int a; #define X a #define Y a int f (void) { if (X == Y) return 1; return 0; } t.c: In function âfâ: t.c:8:9: warning: self-comparison always evaluates to true [-Wtautological-compare] 8 | if (X == Y) return 1; | ^~