private void setAttrType(@NotNull Type targetType, @NotNull Type v) {
        if (targetType.isUnknownType()) {
            Analyzer.self.putProblem(this, "Can't set attribute for UnknownType");
            return;
        }
        // new attr, mark the type as "mutated"
        if (targetType.table.lookupAttr(attr.id) == null ||
                !targetType.table.lookupAttrType(attr.id).equals(v))
        {
            targetType.setMutated(true);
        }
        targetType.table.insert(attr.id, attr, v, ATTRIBUTE);
    }