http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51721
Bug #: 51721 Summary: -Warray-bounds false positives and inconsistencies Classification: Unclassified Product: gcc Version: 4.6.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: tree-optimization AssignedTo: unassig...@gcc.gnu.org ReportedBy: vincent-...@vinc17.net I get strange -Warray-bounds false positives on the following code: static int a[10], b[10], c[10], d[10]; unsigned int f (unsigned int v) { return v == 17 ? 11 : v; } unsigned int g (unsigned int v) { return v == 17 ? 17 : v; } void t (unsigned int s) { if (s >> 1 == 0) { a[f(s)] = 0; a[f(s)] = 0; b[f(s)] = 0; c[g(s)] = 0; c[g(s)] = 0; d[H(s)] = 0; } } With gcc (Debian 4.6.2-9) 4.6.2 on a Debian/x86_64 machine: $ gcc-snapshot -O2 -Warray-bounds -c bounds.c -DH=f bounds.c: In function 't': bounds.c:17:8: warning: array subscript is above array bounds [-Warray-bounds] bounds.c:19:8: warning: array subscript is above array bounds [-Warray-bounds] bounds.c:20:8: warning: array subscript is above array bounds [-Warray-bounds] $ gcc-snapshot -O2 -Warray-bounds -c bounds.c -DH=g bounds.c: In function 't': bounds.c:17:8: warning: array subscript is above array bounds [-Warray-bounds] Note: line 17 is the first "a[f(s)] = 0;".