Add mapping and iterating to new location added to parsetree (fully r…

…eviewed)

(cherry picked from commit 6232a43)

ocaml/parsing/ast_iterator.ml

@@ -140,8 +140,9 @@ module T = struct
     | Ltyp_poly { bound_vars; inner_type } ->
       List.iter (bound_var sub) bound_vars;
       sub.typ sub inner_type
-    | Ltyp_alias { aliased_type; name = _; jkind } ->
+    | Ltyp_alias { aliased_type; name; jkind } ->
       sub.typ sub aliased_type;
+      iter_opt (iter_loc sub) name;
       iter_loc_txt sub sub.jkind_annotation jkind
 
   let iter_jst_labeled_tuple sub : LT.core_type -> _ = function

ocaml/parsing/ast_mapper.ml

@@ -177,6 +177,7 @@ module T = struct
       Ltyp_poly { bound_vars; inner_type }
     | Ltyp_alias { aliased_type; name; jkind } ->
       let aliased_type = sub.typ sub aliased_type in
+      let name = map_opt (map_loc sub) name in
       let jkind = map_loc_txt sub sub.jkind_annotation jkind in
       Ltyp_alias { aliased_type; name; jkind }
 

ocaml/testsuite/tests/typing-layouts/error_message_attr.ml

@@ -126,11 +126,11 @@ module type a = sig
   val f : t -> (t as ('a : value)[@error_message "Custom message"])
 end
 [%%expect{|
-Line 126, characters 22-24:
-126 |   val f : t -> (t as ('a : value)[@error_message "Custom message"])
-                            ^^
-Error: This alias is bound to type "t" but is used as an instance of type
-         "('a : value)"
+Line 3, characters 22-24:
+3 |   val f : t -> (t as ('a : value)[@error_message "Custom message"])
+                          ^^
+Error: This alias is bound to type t but is used as an instance of type
+         ('a : value)
        The layout of t is float64
          because of the definition of t at line 2, characters 2-18.
        But the layout of t must be a sublayout of value