https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103991
--- Comment #7 from rguenther at suse dot de <rguenther at suse dot de> --- > Am 12.01.2022 um 17:33 schrieb jakub at gcc dot gnu.org > <gcc-bugzi...@gcc.gnu.org>: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103991 > > Jakub Jelinek <jakub at gcc dot gnu.org> changed: > > What |Removed |Added > ---------------------------------------------------------------------------- > CC| |rguenth at gcc dot gnu.org > > --- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- > For IF_STMT_CONSTEXPR_P and IF_STMT_CONSTEVAL_P IF_STMTs, it is unclear what > we > should do, because in either case we throw away the other branch if any. > Either we do for those what we used to do before r12-5638 and risk > -Wunreachable-code warnings (when/if it is readded), e.g. on code like: > if constexpr (true) > return 0; > some code; > but we don't emit these -Wreturn-type false positives in cases where the > untaken block of code doesn't fall through. > Or the r12-5638 can result in such false positives. > Or perhaps we should track if we had the other block of code at all (if not, > it > is ok to do what we do right now) and if possible otherwise try to figure out > if the other block could fall through and if it can't, perhaps replace the > void_node with __builtin_unreachable () call? > For IF_STMT_CONSTEVAL_P we still have the other branch around and could > perhaps > call block_may_fallthru on it, but for IF_STMT_CONSTEXPR_P we discard it > earlier, > outside of templates already during parsing. > > Now, as Richi's warning isn't in GCC 12, quickest/safest temporary fix would > be > to revert to previous behavior for IF_STMT_CONSTEXPR_P and > IF_STMT_CONSTEVAL_P, > if (IF_STMT_CONSTEVAL_P (stmt)) > stmt = else_; > else if (IF_STMT_CONSTEXPR_P (stmt)) > stmt = integer_nonzerop (cond) ? then_ ? else_; > else > stmt = build3 (COND_EXPR, void_type_node, cond, then_, else_); I agree that reverting for GCC 12 is the most reasonable thing with adding a Testcase > Jason, thoughts on this? > > -- > You are receiving this mail because: > You are on the CC list for the bug.
