fix(library/type_context): preprocess_class: always solve universe mvars in inout

src/library/type_context.cpp

@@ -3877,7 +3877,7 @@ For all these reasons, we have discarded this alternative design.
 expr type_context::preprocess_class(expr const & type,
                                     buffer<level_pair> & u_replacements,
                                     buffer<expr_pair> &  e_replacements) {
-    if (!has_expr_metavar(type))
+    if (!has_metavar(type))
         return type;
     type_context::tmp_locals locals(*this);
     expr it = type;

tests/lean/run/inout_level.lean

@@ -0,0 +1,8 @@
+section bug
+variables (x y z : Type)
+variables (f : x → y) (g : y → z)
+variables (xy : set (x → y)) (yz : set (y → z)) (xz : set (x → z))
+--#check f ∈ xy
+--#check g ∈ yz
+#check (g ∘ f) ∈ xz --error
+end bug