Actually ignore types not in the recursive group

testsuite/tests/typing-layouts-unboxed-records/recursive.ml

@@ -173,19 +173,16 @@ Error: The definition of "bad" is recursive without boxing:
 type bad = #( s * s )
 and ('a : any) record_id2 = #{ a : 'a }
 and s = #{ u : u }
-and u = #(int * bad alias_id record_id2)
+and u = #(int * bad record_id2)
 [%%expect{|
 Line 1, characters 0-21:
 1 | type bad = #( s * s )
     ^^^^^^^^^^^^^^^^^^^^^
 Error: The definition of "bad" is recursive without boxing:
          "bad" = "#(s * s)",
          "#(s * s)" contains "u",
-         "u" = "#(int * bad alias_id record_id2)",
-         "#(int * bad alias_id record_id2)" contains "bad alias_id",
-         "bad alias_id" = "bad",
-         "bad" = "#(s * s)",
-         "#(s * s)" contains "s"
+         "u" = "#(int * bad record_id2)",
+         "#(int * bad record_id2)" contains "bad"
 |}]
 
 (* We also check recursive types via modules *)
@@ -247,15 +244,21 @@ Error: Unboxed record element types must have a representable layout.
 (***************************************)
 (* Singleton recursive unboxed records *)
 
-(* CR layouts v7.2: allow bounded repetition of the same type constructor of
-   unboxed records. *)
 type 'a safe = #{ a : 'a }
 type x = int safe safe
 [%%expect{|
 type 'a safe = #{ a : 'a; }
-Line 2, characters 0-22:
-2 | type x = int safe safe
-    ^^^^^^^^^^^^^^^^^^^^^^
+type x = int safe safe
+|}]
+
+(* CR layouts v7.2: allow bounded repetition of the same type constructor of
+   unboxed records. *)
+type 'a safe = #{ a : 'a }
+and x = int safe safe
+[%%expect{|
+Line 2, characters 0-21:
+2 | and x = int safe safe
+    ^^^^^^^^^^^^^^^^^^^^^
 Error: The definition of "x" is recursive without boxing:
          "x" = "int safe safe",
          "int safe safe" contains "int safe"

typing/typedecl.ml

@@ -2101,7 +2101,10 @@ let check_unboxed_recursion ~abs_env env loc path0 ty0 to_check =
     | ty' ->
       begin match get_desc ty with
       | Tconstr (path, _, _) ->
-        expand (Path.Set.add path parents) (Expands_to (ty, ty') :: trace) ty'
+        if to_check path then
+          expand (Path.Set.add path parents) (Expands_to (ty, ty') :: trace) ty'
+        else
+          parents, trace, ty
       | _ ->
         (* Only [Tconstr]s can be expanded *)
         Misc.fatal_error "Typedecl.check_unboxed_recursion"
@@ -2115,11 +2118,11 @@ let check_unboxed_recursion ~abs_env env loc path0 ty0 to_check =
     let parents, trace, ty = expand parents trace ty in
     match get_desc ty with
     | Tconstr (path, _, _) ->
-      (* If we get a Tconstr, we only need to visit if it's part of this group
-         of mutually recursive typedecls. *)
-      if not (to_check path) then () else
-      check_visited parents trace ty;
-      visit_subtypes (Path.Set.add path parents) trace ty
+      (* Only visit [Tconstr]s in this recursive group of typedecls. *)
+      if to_check path then begin
+        check_visited parents trace ty;
+        visit_subtypes (Path.Set.add path parents) trace ty
+      end
     | _ ->
       visit_subtypes parents trace ty
   and visit_subtypes parents trace ty =