https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79993
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Created attachment 41072 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41072&action=edit gcc7-pr79993.patch So, one option is to revert to the 4.8 and earlier behavior, disallow any VLA initialization (like C does). This patch should do it. Otherwise, the behavior the C++ FE has when not using string literals as initializers is that it is UB if the VLA is smaller than the size of the initializer, and if it is larger or equal than that, it is initialized from the initializer and excess elements if any are zero initialized (value initialization or whatever it is). Even when ignoring the bogus type on the STRING_CST, we don't implement that right now for STRING_CST - we probably want memcpy from the STRING_CST followed by whatever we do for other initializers.
