https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68907
Bug ID: 68907 Summary: bogus warning: right-hand operand of comma expression has no effect on an atomic_int preincrement Product: gcc Version: 6.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: msebor at gcc dot gnu.org Target Milestone: --- GCC 5.1.0 and current trunk issue the following incorrect warning on the preincrement of an _Atomic variable. $ cat ~/tmp/t.c && /build/gcc-trunk/gcc/xgcc -B /build/gcc-trunk/gcc -S -Wall -Wextra -o/dev/null ~/tmp/t.c $ cat ~/tmp/t.c && /build/gcc-trunk/gcc/xgcc -B /build/gcc-trunk/gcc -S -Wall -Wextra -o/dev/null ~/tmp/t.c typedef _Atomic int AI; extern AI ai; void increment (void) { ++ai; } /home/remote/msebor/tmp/t.c: In function ‘increment’: /home/remote/msebor/tmp/t.c:7:5: warning: right-hand operand of comma expression has no effect [-Wunused-value] ++ai; ^~~~