https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84859
--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> --- The warning is in response to the call to memcpy(d, s, 255) in h(): <bb 8> [local count: 477815112]: a[0] = 255; __builtin_memcpy (&a, p_15(D), 255); _26 = a[0]; The wording seems clear: The function is forming an offset that is out of the bounds of the referenced object. The range of the out-of-bounds offset is [9, 255], while the bounds of the object are [0, 8]. If you think you have of a better/clearer way to phrase it then please propose it.