https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82224
--- Comment #3 from Melissa <myriachan at gmail dot com> --- (In reply to Andrew Pinski from comment #1) > See PR 14319 which I think this is a dup of. PR 14319 refers to a case in which you are allowed to read the common prefix of a structure when the structure is not the active member of the union. In this report, however, it is never the case that an inactive member is accessed. Instead, it appears that GCC isn't aware of aliasing of two pointers when it comes to tracking which is the active member. Melissa
