improve formatting

Author: alanechang

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

@@ -58,8 +58,8 @@ Error: This expression has type float# but an expression was expected of type
        The layout of float# is float64, because
          it is the primitive float64 type float#.
        But the layout of float# must be a sublayout of value, because
-         of the annotation on the wildcard _ at line 1, characters 20-31
-         Custom message.
+         of the annotation on the wildcard _ at line 1, characters 20-31.
+         Custom message
 |}]
 
 let f x =
@@ -74,8 +74,8 @@ Error: This expression has type ('a : value)
        The layout of float# is float64, because
          it is the primitive float64 type float#.
        But the layout of float# must be a sublayout of value, because
-         of the annotation on the wildcard _ at line 2, characters 15-26
-         Custom message.
+         of the annotation on the wildcard _ at line 2, characters 15-26.
+         Custom message
 |}]
 
 (* Ltyp_var { name = Some name; layout } case *)
@@ -90,8 +90,8 @@ Line 3, characters 61-63:
                                                                  ^^
 Error: This type ('a : value) should be an instance of type ('b : float64)
        The layout of 'a is value, because
-         of the annotation on the type variable 'a
-         Custom message.
+         of the annotation on the type variable 'a.
+         Custom message
        But the layout of 'a must overlap with float64, because
          of the definition of t at line 2, characters 2-28.
 |}]
@@ -112,8 +112,8 @@ Error: Bad layout annotation:
          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, because
-           of the annotation on the type variable a
-           Custom message.
+           of the annotation on the type variable a.
+           Custom message
 |}]
 
 (* Second call to [layout_of_annotation] in the Not_found case
@@ -131,8 +131,8 @@ Error: This alias is bound to type t but is used as an instance of type
        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, because
-         of the annotation on the type variable a
-         Custom message.
+         of the annotation on the type variable a.
+         Custom message
 |}]
 
 (* Third call to [layout_of_annotation] in the None case
@@ -149,8 +149,8 @@ Error: Bad layout annotation:
          The layout of t/2 is float64, because
            of the definition of t at line 2, characters 2-18.
          But the layout of t/2 must be a sublayout of value, because
-           of the annotation on the wildcard _ at line 3, characters 26-31
-           Custom message.
+           of the annotation on the wildcard _ at line 3, characters 26-31.
+           Custom message
 |}]
 
 (* Currently it's not possible to attach attributes to Ltyp_poly *)

ocaml/typing/layouts.ml

@@ -704,9 +704,9 @@ module Layout = struct
           fprintf ppf "the type variable %s" name
       | Type_wildcard loc ->
           fprintf ppf "the wildcard _ at %a" Location.print_loc_in_lowercase loc
-      | With_error_message (message, context) ->
-          format_annotation_context ppf context;
-          fprintf ppf "@ @[%s@]" message
+      | With_error_message (_message, context) ->
+          (* message gets printed in [format_flattened_history] so we ignore it here *)
+          format_annotation_context ppf context
 
     let format_any_creation_reason ppf : any_creation_reason -> unit = function
       | Missing_cmi p ->
@@ -868,7 +868,13 @@ module Layout = struct
         end
       | _ -> assert false
       end;
-      fprintf ppf ".@]"
+      fprintf ppf ".";
+      begin match t.history with
+      | Creation (Annotated (With_error_message (message, _), _)) ->
+        fprintf ppf "@ @[%s@]" message
+      | _ -> ()
+      end;
+      fprintf ppf "@]"
 
 
     (* this isn't really formatted for user consumption *)
@@ -998,7 +1004,7 @@ module Layout = struct
   let equate = equate_or_equal ~allow_mutation:true
 
   (* Not all layout history reasons are created equal. Some are more helpful than others.
-     This function tried to encode that information.
+     This function encodes that information.
 
      The reason with higher score should get preserved when combined with one of lower
      score. *)