[Bug tree-optimization/103121] [12 Regression] Warnings in cp/optimize.c causing build failure

[rguenth at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103121

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
  grp_name = XALLOCAVEC (char, IDENTIFIER_LENGTH (complete_name) + 1);

so the array is at least of size 1.  David, can you try adding
-fno-tree-vectorize to the command line to see if that silences the diagnostic?