Function rustc_mir_transform::remove_zsts::involves_a_union

fn involves_a_union<'tcx>(
    place: Place<'tcx>,
    local_decls: &LocalDecls<'tcx>,
    tcx: TyCtxt<'tcx>
) -> bool

Miri lazily allocates memory for locals on assignment, so we must preserve writes to unions and union fields, or it will ICE on reads of those fields.