https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127038
--- Comment #3 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jorgen Kvalsvik <[email protected]>: https://gcc.gnu.org/g:5da256175a9f7a5f82afcd475ac71eb5c065fac8 commit r17-3811-g5da256175a9f7a5f82afcd475ac71eb5c065fac8 Author: Jørgen Kvalsvik <[email protected]> Date: Tue Sep 1 14:14:13 2026 +0200 Check past-the-end before dereferencing iterator Guard the dereference in the case where the current cursor in the needle isn't a tombstone in case we're at the end of the haystack. Example pair: NEEDLE: 6 x x 4 6 HAYSTACK: 4 6 x x 4 We find the subsequence 6 4, but the needle is not yet at end (missing 6) while the haystack is moved past the end: NEEDLE: 6 x x 4 6 ^ HAYSTACK: 4 6 x x 4 ^ If the haystack (super) is exhausted before the needle (sub) we know it isn't a proper subsequence, so this is the correct behaviour. This example was in the testsuite and caught by ASAN. PR gcov-profile/127038 gcc/ChangeLog: * gcov.cc (tombstone_subsequence_p): Guard iterator dereference.
