https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70765
--- Comment #2 from Mike Conlen <mike at conlen dot org> --- If I compile with -O3 the compiler produces (as expected) $ gcc -Wall -Wextra -Werror -save-temps -O3 -c test.c test.c: In function 'try_to_fail': test.c:25:2: error: 'data' is used uninitialized in this function [-Werror=uninitialized] arbitrary_function(data); ^ test.c: In function 'main': test.c:25:2: error: 'data' is used uninitialized in this function [-Werror=uninitialized] test.c:18:7: note: 'data' was declared here int *data; ^ cc1: all warnings being treated as errors