+
+ if mtype isa MClassType then
+ v.modelbuilder.warning(self, "Warning: expression is already not null, since it is a `{mtype}`.")
+ return
+ end
+ assert mtype.need_anchor
+ var u = v.anchor_to(mtype)
+ if not u isa MNullableType then
+ v.modelbuilder.warning(self, "Warning: expression is already not null, since it is a `{mtype}: {u}`.")
+ return
+ end