https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101403
--- Comment #5 from Zdenek Sojka <zsojka at seznam dot cz> --- (In reply to Jakub Jelinek from comment #4) > Isn't the testcase UB? It reads uninitialized u (though it doesn't use the > value for anything). You are very right about that! The value is used, even though the use is optimised out. I am using -fsanitize=undefined when reducing testcases, but this one wasn't caught. The only warning I see with -Wall -W is "warning: left-hand operand of comma expression has no effect [-Wunused-value]". valgrind also doesn't complain because, obviously, the uninitialised read is optimised out.
