https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101090
Bug ID: 101090 Summary: incorrect -Wunused-value warning on remquo with constant values Product: gcc Version: 9.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: vincent-gcc at vinc17 dot net Target Milestone: --- When remquo is used with constant values, GCC emits the following warning: warning: right-hand operand of comma expression has no effect [-Wunused-value] According to the following testcase compiled with the "-Wunused-value -c" options, the warning is obtained only for f2, i.e. is does not occur when the function is not called remquo or when non-constant values are used. double r (double, double, int *); double remquo (double, double, int *); int f1 (void) { int quo; r (1.0, 3.0, &quo); return quo; } int f2 (void) { int quo; remquo (1.0, 3.0, &quo); return quo; } int f3 (double x, double y) { int quo; remquo (x, y, &quo); return quo; } Testcase also available on https://godbolt.org/z/Px44sxn4h for testing, where I can see that this bug was introduced in GCC 9.1.0 and is still present in the trunk.