https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81897
--- Comment #16 from Arnd Bergmann <arnd at linaro dot org> --- Created attachment 43056 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43056&action=edit linux/net/ipv6/route.c, preprocessed and compressed To test the patch, I reverted the workaround that was added to the kernel when I originally reported this. Unfortunately the warning is still there, only the reduced version is fixed. I attached the preprocessed source now, test with $ x86_64-linux-gcc-8.0.0 -fno-strict-aliasing -Wall -O2 -Wno-pointer-sign -c route-1.i /git/arm-soc/net/ipv6/route.c: In function 'inet6_rtm_getroute': /git/arm-soc/net/ipv6/route.c:4350:9: warning: 'dst' may be used uninitialized in this function [-Wmaybe-uninitialized] goto errout; ^~~~~~ } Reducing this with the latest gcc-8.0.0 snapshot gave me enum { true } fn1(); int inet6_rtm_getroute_iif, inet6_rtm_getroute_rt, inet6_rtm_getroute_rtm_0; int *inet6_rtm_getroute___trans_tmp_8; int fn2(); void fn3() { int *dst; _Bool fibmatch = inet6_rtm_getroute_rtm_0 & 2; if (inet6_rtm_getroute_iif) { if (!fibmatch) dst = inet6_rtm_getroute___trans_tmp_8; static _Bool __warned; fn2() && __warned &&fn1(); __warned = true; } else if (!fibmatch) dst = 0; if (fibmatch) dst = 0; inet6_rtm_getroute_rt = *dst; }
