2b0e730bf3
More `transmute_undefined_repr` fixes fixes: #8498 fixes: #8501 fixes: #8503 changelog: Allow `transumte_undefined_repr` between fat pointers and `(usize, usize)` changelog: Allow `transumte_undefined_repr` when one side is a union changelog: Fix `transumte_undefined_repr` on tuples with one non-zero-sized type.