diff --git a/changes/signature-mismatch-layout.polish.md b/changes/signature-mismatch-layout.polish.md
new file mode 100644
index 0000000000..045431d14d
--- /dev/null
+++ b/changes/signature-mismatch-layout.polish.md
@@ -0,0 +1,2 @@
+- Show a signature mismatch as the actual and the expected declaration, each under its location, with only the items that differ and the module path to them.
+- Keep the location of an extension constructor or exception declared in an interface, so that errors and reanalyze point to it.
diff --git a/compiler/ml/ast_untagged_variants.ml b/compiler/ml/ast_untagged_variants.ml
index 2b43fdd6fe..d9d746eb5e 100644
--- a/compiler/ml/ast_untagged_variants.ml
+++ b/compiler/ml/ast_untagged_variants.ml
@@ -322,16 +322,16 @@ let runtime_annotation_to_string = function
   | Type_of block_type ->
     Printf.sprintf "@%s(\"%s\")" type_of (typeof_name block_type)
 
-(* What a declaration's annotations state, for error messages *)
-let describe_declared_block_type = function
+(* What a declaration's annotations state about its values, for error
+   messages *)
+let describe_declared_values = function
   | Some (InstanceType (Class {name; ancestors = []})) -> "instances of " ^ name
   | Some (InstanceType (Class {name; ancestors})) ->
     "instances of " ^ name ^ ", a subclass of "
     ^ String.concat " and " ancestors
   | Some (InstanceType Array) -> "arrays"
-  | Some block_type ->
-    "values whose typeof is \"" ^ typeof_name block_type ^ "\""
-  | None -> "no runtime class or typeof"
+  | Some block_type -> "typeof \"" ^ typeof_name block_type ^ "\""
+  | None -> "no stated class or typeof"
 
 (* The [@notUndefined], [@instanceOf] or [@typeOf] annotation in [attrs],
    validated. Only [Typedecl] passes [~loc]; later readers see attributes it
diff --git a/compiler/ml/includecore.ml b/compiler/ml/includecore.ml
index 99414e9078..3579398672 100644
--- a/compiler/ml/includecore.ml
+++ b/compiler/ml/includecore.ml
@@ -191,6 +191,16 @@ type type_mismatch =
   | Runtime_annotation of string * string
   | Not_undefined
 
+(* A side of a comparison as a label: "the actual" and "declaration" make
+   "Actual declaration" *)
+let label side decl =
+  let side =
+    match String.split_on_char ' ' side with
+    | "the" :: rest -> String.concat " " rest
+    | _ -> side
+  in
+  String.capitalize_ascii (side ^ " " ^ decl)
+
 let report_type_mismatch0 first second decl ppf err =
   let pr fmt = Format.fprintf ppf fmt in
   match err with
@@ -225,27 +235,31 @@ let report_type_mismatch0 first second decl ppf err =
   | Record_representation (_rep1, _rep2) ->
     pr "Their internal representations differ"
   | Unboxed_representation b ->
-    pr "Their internal representations differ:@ %s %s %s"
-      (if b then second else first)
+    pr "@[<v 2>Their internal representations differ:@,%s %s %s@]"
+      (String.capitalize_ascii (if b then second else first))
       decl "uses unboxed representation"
-  | Immediate -> pr "%s is not an immediate type" first
+  | Immediate -> pr "%s %s is not an immediate type" first decl
   | Tag_name -> pr "Their @tag annotations differ"
   | Variant_representation s ->
     pr "The internal representations for case %s are not equal" (Ident.name s)
   | Not_undefined ->
     pr
-      "Their runtime representations differ:@ %s %s is @notUndefined,@ but %s \
-       %s can hold undefined"
-      second decl first decl
+      "@[<v 2>Their runtime representations differ:@,\
+       %s: can hold undefined@,\
+       %s: @notUndefined@]"
+      (label first decl) (label second decl)
   | Runtime_annotation (declared1, declared2) ->
-    pr
-      "Their runtime representations differ:@ %s %s states %s,@ %s %s states %s"
-      first decl declared1 second decl declared2
+    pr "@[<v 2>Their runtime representations differ:@,%s: %s@,%s: %s@]"
+      (label first decl) declared1 (label second decl) declared2
 
 let report_type_mismatch first second decl ppf =
   List.iter (fun err ->
-      if err = Manifest then ()
-      else
+      match err with
+      | Manifest -> ()
+      (* Its lines are labels, not sentences *)
+      | Runtime_annotation _ | Not_undefined ->
+        Format.fprintf ppf "@ %a" (report_type_mismatch0 first second decl) err
+      | _ ->
         Format.fprintf ppf "@ %a." (report_type_mismatch0 first second decl) err)
 
 let rec compare_constructor_arguments env cstr params1 params2 arg1 arg2 =
@@ -390,8 +404,8 @@ let compare_runtime_annotations env id decl1 decl2 =
     else
       [
         Runtime_annotation
-          ( Ast_untagged_variants.describe_declared_block_type declared1,
-            Ast_untagged_variants.describe_declared_block_type declared2 );
+          ( Ast_untagged_variants.describe_declared_values declared1,
+            Ast_untagged_variants.describe_declared_values declared2 );
       ]
 
 let type_declarations ?(equality = false) ~loc env name decl1 id decl2 =
diff --git a/compiler/ml/includemod.ml b/compiler/ml/includemod.ml
index e3f7fcc568..aee078f519 100644
--- a/compiler/ml/includemod.ml
+++ b/compiler/ml/includemod.ml
@@ -20,7 +20,8 @@ open Typedtree
 open Types
 
 type symptom =
-  | Missing_field of Ident.t * Location.t * string (* kind *)
+  | Missing_field of Ident.t * Location.t * string * signature_item
+      (** The name, location, kind and declaration of an expected item *)
   | Value_descriptions of Ident.t * value_description * value_description
   | Type_declarations of
       Ident.t
@@ -42,6 +43,9 @@ type pos =
   | Modtype of Ident.t
   | Arg of Ident.t
   | Body of Ident.t
+  | Reverse
+      (** The module types at this position compared the other way round, in
+          the second half of an equivalence check *)
 type error = pos list * Env.t * symptom
 
 exception Error of error list
@@ -331,7 +335,8 @@ and signatures ~loc env cxt subst sig1 sig2 =
           (* see PR#5098 *)
           simplify_structure_coercion cc id_pos_list runtime_fields
         else Tcoerce_structure (cc, id_pos_list, runtime_fields)
-      | _ -> raise (Error unpaired))
+      (* In the order of the expected signature *)
+      | _ -> raise (Error (List.rev unpaired)))
     | item2 :: rem -> (
       let id2, loc, name2 = item_ident_name item2 in
       let name2, report =
@@ -357,7 +362,7 @@ and signatures ~loc env cxt subst sig1 sig2 =
       | exception Not_found ->
         let unpaired =
           if report then
-            (cxt, env, Missing_field (id2, loc, kind_of_field_desc name2))
+            (cxt, env, Missing_field (id2, loc, kind_of_field_desc name2, item2))
             :: unpaired
           else unpaired
         in
@@ -421,7 +426,7 @@ and modtype_infos ~loc env cxt subst id info1 info2 =
 and check_modtype_equiv ~loc env cxt mty1 mty2 =
   match
     ( modtypes ~loc env cxt Subst.identity mty1 mty2,
-      modtypes ~loc env cxt Subst.identity mty2 mty1 )
+      modtypes ~loc env (Reverse :: cxt) Subst.identity mty2 mty1 )
   with
   | Tcoerce_none, Tcoerce_none -> ()
   | _c1, _c2 ->
@@ -485,12 +490,21 @@ let modtypes env m1 m2 =
 open Format
 open Printtyp
 
-let show_loc msg ppf loc =
-  fprintf ppf "@\n@[<2>%a:@ %s@]" Location.print_loc loc msg
+(* A declaration under a label naming its side and its location *)
+let show_declaration label loc pp ppf x =
+  fprintf ppf "@[<v 2>%s (%a):@,%a@]" label Location.print_loc loc pp x
 
-let show_locs ppf (loc1, loc2) =
-  show_loc "Expected declaration" ppf loc2;
-  show_loc "Actual declaration" ppf loc1
+(* [x1] is included in [x2]. In a functor's parameter, where inclusion goes
+   the other way, [swapped] is true and [x2] is the actual declaration. *)
+let show_declarations ~swapped pp ppf (x1, loc1, x2, loc2) =
+  let (actual, actual_loc), (expected, expected_loc) =
+    if swapped then ((x2, loc2), (x1, loc1)) else ((x1, loc1), (x2, loc2))
+  in
+  fprintf ppf "%a@,@,%a"
+    (show_declaration "Actual declaration" actual_loc pp)
+    actual
+    (show_declaration "Expected declaration" expected_loc pp)
+    expected
 
 let find_arity_mismatch env ty1 ty2 =
   let rec loop seen ty1 ty2 =
@@ -535,47 +549,57 @@ let show_arity_mismatch env ppf (d1 : value_description)
       if n = 1 then "1 argument" else string_of_int n ^ " arguments"
     in
     fprintf ppf
-      "@\n\
+      "@,\
+       @,\
        @[The implementation contains a function taking %s where the interface \
        expects one taking %s.@]"
       (args n1) (args n2)
   | _ -> ()
 
-let include_symptom env ppf = function
-  | Missing_field (id, loc, kind) ->
-    fprintf ppf "The %s `%a` is required but not provided" kind ident id;
-    show_loc "Expected declaration" ppf loc
+let include_symptom ~swapped env ppf = function
+  | Missing_field (id, loc, kind, item) ->
+    (* Reversed, the item is one the actual declaration has and the expected
+       one lacks *)
+    if swapped then
+      fprintf ppf "The %s `%a` is only present in the actual declaration.@,@,%a"
+        kind ident id
+        (show_declaration "Actual declaration" loc signature)
+        [item]
+    else
+      fprintf ppf "The %s `%a` is required but not provided.@,@,%a" kind ident
+        id
+        (show_declaration "Expected declaration" loc signature)
+        [item]
   | Value_descriptions (id, d1, d2) ->
-    fprintf ppf
-      "@[<hv 2>Values do not match:@ %a@;<1 -2>is not included in@ %a@]"
-      (value_description id) d1 (value_description id) d2;
-    show_arity_mismatch env ppf d1 d2;
-    show_locs ppf (d1.val_loc, d2.val_loc)
+    show_declarations ~swapped (value_description id) ppf
+      (d1, d1.val_loc, d2, d2.val_loc);
+    if swapped then show_arity_mismatch env ppf d2 d1
+    else show_arity_mismatch env ppf d1 d2
   | Type_declarations (id, d1, d2, errs) ->
-    fprintf ppf "@[<v>@[<hv>%s:@;<1 2>%a@ %s@;<1 2>%a@]%a%a@]"
-      "Type declarations do not match" (type_declaration id) d1
-      "is not included in" (type_declaration id) d2 show_locs
-      (d1.type_loc, d2.type_loc)
-      (Includecore.report_type_mismatch "the first" "the second" "declaration")
-      errs
+    show_declarations ~swapped (type_declaration id) ppf
+      (d1, d1.type_loc, d2, d2.type_loc);
+    if List.exists (fun err -> err <> Includecore.Manifest) errs then
+      let first, second =
+        if swapped then ("the expected", "the actual")
+        else ("the actual", "the expected")
+      in
+      fprintf ppf "@,%a"
+        (Includecore.report_type_mismatch first second "declaration")
+        errs
   | Extension_constructors (id, x1, x2) ->
-    fprintf ppf
-      "@[<hv 2>Extension declarations do not match:@ %a@;\
-       <1 -2>is not included in@ %a@]"
-      (extension_constructor id) x1 (extension_constructor id) x2;
-    show_locs ppf (x1.ext_loc, x2.ext_loc)
+    show_declarations ~swapped (extension_constructor id) ppf
+      (x1, x1.ext_loc, x2, x2.ext_loc)
   | Module_types (mty1, mty2) ->
+    let actual, expected = if swapped then (mty2, mty1) else (mty1, mty2) in
     fprintf ppf
-      "@[<hv 2>Modules do not match:@ %a@;<1 -2>is not included in@ %a@]"
-      modtype mty1 modtype mty2
+      "@[<v 2>Actual module type:@,%a@]@,@,@[<v 2>Expected module type:@,%a@]"
+      modtype actual modtype expected
   | Modtype_infos (id, d1, d2) ->
-    fprintf ppf
-      "@[<hv 2>Module type declarations do not match:@ %a@;\
-       <1 -2>does not match@ %a@]"
-      (modtype_declaration id) d1 (modtype_declaration id) d2
+    show_declarations ~swapped (modtype_declaration id) ppf
+      (d1, d1.mtd_loc, d2, d2.mtd_loc)
   | Modtype_permutation -> fprintf ppf "Illegal permutation of structure fields"
   | Interface_mismatch (impl_name, intf_name) ->
-    fprintf ppf "@[The implementation %s@ does not match the interface %s:"
+    fprintf ppf "@[The implementation %s@ does not match the interface %s:@]"
       impl_name intf_name
   | Unbound_modtype_path path ->
     fprintf ppf "Unbound module type %a" Printtyp.path path
@@ -590,6 +614,7 @@ let rec context ppf = function
     fprintf ppf "@[<2>module type %a =@ %a@]" ident id context_mty rem
   | Body x :: rem -> fprintf ppf "(%s) =>@ %a" (argname x) context_mty rem
   | Arg x :: rem -> fprintf ppf "(%a:@ %a) => ..." ident x context_mty rem
+  | Reverse :: rem -> context ppf rem
   | [] -> fprintf ppf "<here>"
 
 and context_mty ppf = function
@@ -603,75 +628,97 @@ and argname x =
   let s = Ident.name x in
   if s = "*" then "" else s
 
-let path_of_context = function
+(* The path of the modules a context goes through, outermost first *)
+let path_of_modules = function
   | Module id :: rem ->
     let rec subm path = function
-      | [] -> path
+      | [] -> Some path
       | Module id :: rem -> subm (Pdot (path, Ident.name id, -1)) rem
-      | _ -> assert false
+      | (Modtype _ | Arg _ | Body _ | Reverse) :: _ -> None
     in
     subm (Pident id) rem
-  | _ -> assert false
+  | (Modtype _ | Arg _ | Body _ | Reverse) :: _ | [] -> None
 
+(* Where in the module an error is, as a line before it. [cxt] is outermost
+   first. A module type or a functor's result at the end of a module path is
+   named in words; any other position is shown as a module type with <here>. *)
 let context ppf cxt =
+  let split_last l =
+    match List.rev l with
+    | last :: rev_init -> Some (List.rev rev_init, last)
+    | [] -> None
+  in
   if cxt = [] then ()
-  else if
-    List.for_all
-      (function
-        | Module _ -> true
-        | _ -> false)
-      cxt
-  then fprintf ppf "In module %a:@ " path (path_of_context cxt)
-  else fprintf ppf "@[<hv 2>At position@ %a@]@ " context cxt
-
-let include_err ppf (cxt, env, err) =
-  Printtyp.wrap_printing_env env (fun () ->
-      fprintf ppf "@[<v>%a%a@]" context (List.rev cxt) (include_symptom env) err)
-
-let error_size = 400 (* in heap words *)
-
-(* An error part is big when its heap representation exceeds
-   [error_size] words. Each distinct reachable block counts its header
-   and fields; a block without scannable fields (string, float, custom) or a
-   closure counts its header only. String contents are excluded so that the
-   decision is independent of source file names stored in locations. The walk
-   stops as soon as the limit is exceeded, which bounds the visited list. *)
-let is_big obj =
-  let size = ref 0 in
-  let visited = ref [] in
-  let exception Big in
-  let rec walk (o : Obj.t) =
-    if Obj.is_block o && not (List.memq o !visited) then (
-      visited := o :: !visited;
-      let tag = Obj.tag o in
-      let scan =
-        tag < Obj.no_scan_tag && tag <> Obj.closure_tag && tag <> Obj.infix_tag
-      in
-      size := !size + if scan then 1 + Obj.size o else 1;
-      if !size > error_size then raise_notrace Big;
-      if scan then
-        for i = 0 to Obj.size o - 1 do
-          walk (Obj.field o i)
-        done)
+  else
+    match (path_of_modules cxt, split_last cxt) with
+    | Some p, _ -> fprintf ppf "In module %a:@,@," path p
+    | None, Some ([], Modtype id) ->
+      fprintf ppf "In module type %a:@,@," ident id
+    | None, Some (modules, Modtype id) -> (
+      match path_of_modules modules with
+      | Some p -> fprintf ppf "In module type %a.%a:@,@," path p ident id
+      | None -> fprintf ppf "@[<hv 2>At position@ %a@]@,@," context cxt)
+    | None, Some (modules, Body _) -> (
+      match path_of_modules modules with
+      | Some p -> fprintf ppf "In the result of functor %a:@,@," path p
+      | None -> fprintf ppf "@[<hv 2>At position@ %a@]@,@," context cxt)
+    | None, Some (modules, Arg x) -> (
+      match path_of_modules modules with
+      | Some p ->
+        fprintf ppf "In the parameter %a of functor %a:@,@," ident x path p
+      | None -> fprintf ppf "@[<hv 2>At position@ %a@]@,@," context cxt)
+    | None, _ -> fprintf ppf "@[<hv 2>At position@ %a@]@,@," context cxt
+
+let include_err ~show_context ppf (cxt, env, err) =
+  (* Inclusion is reversed in each functor parameter on the way, and in the
+     second half of an equivalence check of module types *)
+  let swapped =
+    List.length
+      (List.filter
+         (function
+           | Arg _ | Reverse -> true
+           | Module _ | Modtype _ | Body _ -> false)
+         cxt)
+    mod 2
+    = 1
   in
-  try
-    walk (Obj.repr obj);
-    false
-  with Big -> true
-
+  Printtyp.wrap_printing_env env (fun () ->
+      fprintf ppf "@[<v>%a%a@]"
+        (fun ppf cxt -> if show_context then context ppf cxt)
+        (List.rev (List.filter (fun pos -> pos <> Reverse) cxt))
+        (include_symptom ~swapped env)
+        err)
+
+(* An error is a path of symptoms from the whole module down to the items that
+   differ. The modules on the way are left out, as the items at the end say
+   what differs, each under the position it is at. *)
 let report_error ppf errs =
-  if errs = [] then ()
-  else
-    let errs, err = Ext_list.split_at_last errs in
-    let pe = ref true in
-    let include_err' ppf ((_, _, obj) as err) =
-      if not (is_big obj) then fprintf ppf "%a@ " include_err err
-      else if !pe then (
-        fprintf ppf "...@ ";
-        pe := false)
-    in
-    let print_errs ppf = List.iter (include_err' ppf) in
-    fprintf ppf "@[<v>%a%a@]" print_errs errs include_err err
+  (* Whether a symptom shows the declarations that differ. A permutation of
+     fields doesn't, so the comparison of the module types around it stays. *)
+  let shows_declarations (_, _, symptom) =
+    match symptom with
+    | Missing_field _ | Value_descriptions _ | Type_declarations _
+    | Extension_constructors _ | Module_types _ | Modtype_infos _ ->
+      true
+    | Modtype_permutation | Interface_mismatch _ | Unbound_modtype_path _
+    | Unbound_module_path _ | Invalid_module_alias _ ->
+      false
+  in
+  let rec shown = function
+    | [] -> []
+    | (_, _, (Module_types _ | Modtype_infos _)) :: rest
+      when List.exists shows_declarations rest ->
+      shown rest
+    | err :: rest -> err :: shown rest
+  in
+  let rec print ppf previous_cxt = function
+    | [] -> ()
+    | ((cxt, _, _) as err) :: rest ->
+      if previous_cxt <> None then fprintf ppf "@,@,";
+      include_err ~show_context:(previous_cxt <> Some cxt) ppf err;
+      print ppf (Some cxt) rest
+  in
+  fprintf ppf "@[<v>%a@]" (fun ppf errs -> print ppf None errs) (shown errs)
 
 let better_candidate_loc (x : error list) =
   match x with
@@ -679,7 +726,7 @@ let better_candidate_loc (x : error list) =
     match descr with
     | Value_descriptions (_, d1, _) -> Some d1.val_loc
     | Type_declarations (_, tdcl1, _, _) -> Some tdcl1.type_loc
-    | Missing_field (_, loc, _) -> Some loc
+    | Missing_field (_, loc, _, _) -> Some loc
     | _ -> None)
   | _ -> None
 
diff --git a/compiler/ml/includemod.mli b/compiler/ml/includemod.mli
index 9399f2b63a..e50087dd12 100644
--- a/compiler/ml/includemod.mli
+++ b/compiler/ml/includemod.mli
@@ -38,7 +38,8 @@ val type_declarations :
 val print_coercion : formatter -> module_coercion -> unit
 
 type symptom =
-  | Missing_field of Ident.t * Location.t * string (* kind *)
+  | Missing_field of Ident.t * Location.t * string * signature_item
+      (** The name, location, kind and declaration of an expected item *)
   | Value_descriptions of Ident.t * value_description * value_description
   | Type_declarations of
       Ident.t
@@ -60,6 +61,9 @@ type pos =
   | Modtype of Ident.t
   | Arg of Ident.t
   | Body of Ident.t
+  | Reverse
+      (** The module types at this position compared the other way round, in
+          the second half of an equivalence check *)
 type error = pos list * Env.t * symptom
 
 exception Error of error list
diff --git a/compiler/ml/subst.ml b/compiler/ml/subst.ml
index ea599a6df9..ff62839a2b 100644
--- a/compiler/ml/subst.ml
+++ b/compiler/ml/subst.ml
@@ -304,7 +304,7 @@ let extension_constructor s ext =
         ext_ret_type = may_map (typexp_rec s) ext.ext_ret_type;
         ext_private = ext.ext_private;
         ext_attributes = attrs s ext.ext_attributes;
-        ext_loc = (if s.for_saving then Location.none else ext.ext_loc);
+        ext_loc = loc s ext.ext_loc;
         ext_is_exception = ext.ext_is_exception;
       })
 
diff --git a/compiler/ml/typemod.ml b/compiler/ml/typemod.ml
index 352e283c34..5f9fc41d15 100644
--- a/compiler/ml/typemod.ml
+++ b/compiler/ml/typemod.ml
@@ -1858,7 +1858,7 @@ let report_error ppf = function
   | Cannot_apply mty ->
     fprintf ppf "@[This module is not a functor; it has type@ %a@]" modtype mty
   | Not_included errs ->
-    fprintf ppf "@[<v>Signature mismatch:@ %a@]" Includemod.report_error errs
+    fprintf ppf "@[<v>Signature mismatch:@,@,%a@]" Includemod.report_error errs
   | Cannot_eliminate_dependency mty ->
     fprintf ppf
       "@[This functor has type@ %a@ The parameter cannot be eliminated in the \
@@ -1874,12 +1874,16 @@ let report_error ppf = function
   | With_mismatch (lid, explanation) ->
     fprintf ppf
       "@[<v>@[In this `with' constraint, the new definition of %a@ does not \
-       match its original definition@ in the constrained signature:@]@ %a@]"
+       match its original definition@ in the constrained signature:@]@,\
+       @,\
+       %a@]"
       longident lid Includemod.report_error explanation
   | With_makes_applicative_functor_ill_typed (lid, path, explanation) ->
     fprintf ppf
       "@[<v>@[This `with' constraint on %a makes the applicative functor @ \
-       type %s ill-typed in the constrained signature:@]@ %a@]"
+       type %s ill-typed in the constrained signature:@]@,\
+       @,\
+       %a@]"
       longident lid (Path.name path) Includemod.report_error explanation
   | With_changes_module_alias (lid, id, path) ->
     fprintf ppf
diff --git a/compiler/syntax/src/res_core.ml b/compiler/syntax/src/res_core.ml
index 0f6aeb23de..7dd62d872f 100644
--- a/compiler/syntax/src/res_core.ml
+++ b/compiler/syntax/src/res_core.ml
@@ -7244,6 +7244,7 @@ and parse_module_declaration_or_alias ~attrs p =
 
 and parse_module_type_declaration ~attrs ~start_pos p =
   Parser.expect Typ p;
+  let name_start = Parser.start_pos p in
   let module_name =
     match Parser.peek p with
     | Uident ident ->
@@ -7265,7 +7266,12 @@ and parse_module_type_declaration ~attrs ~start_pos p =
       Some (parse_module_type p)
     | _ -> None
   in
-  let module_decl = Ast_helper.Mtd.mk ~attrs ?typ module_name in
+  (* From the name, like a module type declaration in a structure *)
+  let module_decl =
+    Ast_helper.Mtd.mk ~attrs
+      ~loc:(mk_loc name_start (Parser.position p))
+      ?typ module_name
+  in
   Ast_helper.Sig.modtype ~loc:(mk_loc start_pos (Parser.position p)) module_decl
 
 and parse_sign_let_desc ~attrs p =
diff --git a/tests/analysis_tests/tests-reanalyze/deadcode/expected/deadcode.txt b/tests/analysis_tests/tests-reanalyze/deadcode/expected/deadcode.txt
index 31a01159cd..19aa504667 100644
--- a/tests/analysis_tests/tests-reanalyze/deadcode/expected/deadcode.txt
+++ b/tests/analysis_tests/tests-reanalyze/deadcode/expected/deadcode.txt
@@ -1463,6 +1463,8 @@
   addDeclaration_ Value +test Shadow.res:11:6 path:+Shadow.M
   addDeclaration_ Value +test Shadow.res:9:6 path:+Shadow.M
   Scanning TestDeadExn.cmt Source:TestDeadExn.res
+  add_value_reference TestDeadExn.res:1:12 --> DeadExn.resi:2:0
+  add_type_reference TestDeadExn.res:1:12 --> DeadExn.resi:2:0
   Scanning TestEmitInnerModules.cmt Source:TestEmitInnerModules.res
   addDeclaration_ Value +x TestEmitInnerModules.res:3:6 path:+TestEmitInnerModules.Inner
   addDeclaration_ Value +y TestEmitInnerModules.res:5:6 path:+TestEmitInnerModules.Inner
diff --git a/tests/build_tests/super_errors/expected/OptionalImplIntf.res.expected b/tests/build_tests/super_errors/expected/OptionalImplIntf.res.expected
index fc2ba80ba7..26f6bde724 100644
--- a/tests/build_tests/super_errors/expected/OptionalImplIntf.res.expected
+++ b/tests/build_tests/super_errors/expected/OptionalImplIntf.res.expected
@@ -10,20 +10,11 @@
   6 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = {x: int}
-    }
-  is not included in
-    {
-      type t = {x?: int}
-    }
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/OptionalImplIntf.res:4:3-19):
     type t = {x: int}
-  is not included in
+  
+  Expected declaration (/.../fixtures/OptionalImplIntf.res:2:3-20):
     type t = {x?: int}
-  /.../fixtures/OptionalImplIntf.res:2:3-20:
-    Expected declaration
-  /.../fixtures/OptionalImplIntf.res:4:3-19:
-    Actual declaration
+  
   The optional attribute of field x is different.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/OptionalInlineImplIntf.res.expected b/tests/build_tests/super_errors/expected/OptionalInlineImplIntf.res.expected
index 5cf4df5ff6..c3734353b5 100644
--- a/tests/build_tests/super_errors/expected/OptionalInlineImplIntf.res.expected
+++ b/tests/build_tests/super_errors/expected/OptionalInlineImplIntf.res.expected
@@ -10,20 +10,11 @@
   6 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = A({x: int})
-    }
-  is not included in
-    {
-      type t = A({x?: int})
-    }
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/OptionalInlineImplIntf.res:4:3-22):
     type t = A({x: int})
-  is not included in
+  
+  Expected declaration (/.../fixtures/OptionalInlineImplIntf.res:2:3-23):
     type t = A({x?: int})
-  /.../fixtures/OptionalInlineImplIntf.res:2:3-23:
-    Expected declaration
-  /.../fixtures/OptionalInlineImplIntf.res:4:3-22:
-    Actual declaration
+  
   The optional attribute of field x is different.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/RecordInclusion.res.expected b/tests/build_tests/super_errors/expected/RecordInclusion.res.expected
index 19232b7660..9729e2201e 100644
--- a/tests/build_tests/super_errors/expected/RecordInclusion.res.expected
+++ b/tests/build_tests/super_errors/expected/RecordInclusion.res.expected
@@ -10,13 +10,11 @@
   6 │ 
 
   Signature mismatch:
-  ...
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/RecordInclusion.res:4:3-58):
     type t<'a, 'b, 'c> = {x: int, y: list<('a, 'c)>, z: int}
-  is not included in
+  
+  Expected declaration (/.../fixtures/RecordInclusion.res:2:3-58):
     type t<'a, 'b, 'c> = {x: int, y: list<('a, 'b)>, z: int}
-  /.../fixtures/RecordInclusion.res:2:3-58:
-    Expected declaration
-  /.../fixtures/RecordInclusion.res:4:3-58:
-    Actual declaration
+  
   The types for field y are not equal.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/UntaggedImplIntf.res.expected b/tests/build_tests/super_errors/expected/UntaggedImplIntf.res.expected
index cd7098b36e..f9dabbfdb3 100644
--- a/tests/build_tests/super_errors/expected/UntaggedImplIntf.res.expected
+++ b/tests/build_tests/super_errors/expected/UntaggedImplIntf.res.expected
@@ -10,21 +10,12 @@
   6 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = @as(null) A
-    }
-  is not included in
-    {
-      @unboxed type t = @as(null) A
-    }
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/UntaggedImplIntf.res:4:3-24):
     type t = @as(null) A
-  is not included in
+  
+  Expected declaration (/.../fixtures/UntaggedImplIntf.res:2:12-33):
     @unboxed type t = @as(null) A
-  /.../fixtures/UntaggedImplIntf.res:2:12-33:
-    Expected declaration
-  /.../fixtures/UntaggedImplIntf.res:4:3-24:
-    Actual declaration
+  
   Their internal representations differ:
-  the second declaration uses unboxed representation.
\ No newline at end of file
+    The expected declaration uses unboxed representation.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/functor_apply_arg_mismatch.res.expected b/tests/build_tests/super_errors/expected/functor_apply_arg_mismatch.res.expected
index d027d93b24..18625c79b0 100644
--- a/tests/build_tests/super_errors/expected/functor_apply_arg_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/functor_apply_arg_mismatch.res.expected
@@ -9,12 +9,8 @@
   15 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      let unrelated: string
-    }
-  is not included in
-    HasFoo
-  The value `foo` is required but not provided
-  /.../fixtures/functor_apply_arg_mismatch.res:2:3-14:
-    Expected declaration
\ No newline at end of file
+  
+  The value `foo` is required but not provided.
+  
+  Expected declaration (/.../fixtures/functor_apply_arg_mismatch.res:2:3-14):
+    let foo: int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/functor_signature_mismatch.res.expected b/tests/build_tests/super_errors/expected/functor_signature_mismatch.res.expected
index 1be12f852e..d732eb3baa 100644
--- a/tests/build_tests/super_errors/expected/functor_signature_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/functor_signature_mismatch.res.expected
@@ -12,42 +12,11 @@
   12 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      module F: (X: S) => {
-        type t = int
-      }
-    }
-  is not included in
-    {
-      module F: (X: S) => {
-        type t = X.t
-      }
-    }
-  In module F:
-  Modules do not match:
-    (X: S) => {
-      type t = int
-    }
-  is not included in
-    (X: S) => {
-      type t = X.t
-    }
-  At position module F: (X) => <here>
-  Modules do not match:
-    {
-      type t = int
-    }
-  is not included in
-    {
-      type t = X.t
-    }
-  At position module F: (X) => <here>
-  Type declarations do not match:
+  
+  In the result of functor F:
+  
+  Actual declaration (/.../fixtures/functor_signature_mismatch.res:9:5-16):
     type t = int
-  is not included in
-    type t = X.t
-  /.../fixtures/functor_signature_mismatch.res:6:36:
-    Expected declaration
-  /.../fixtures/functor_signature_mismatch.res:9:5-16:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/functor_signature_mismatch.res:6:36):
+    type t = X.t
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/gadt_constructor_signature_mismatch.res.expected b/tests/build_tests/super_errors/expected/gadt_constructor_signature_mismatch.res.expected
index e9edddbcf4..d67ba3eef3 100644
--- a/tests/build_tests/super_errors/expected/gadt_constructor_signature_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/gadt_constructor_signature_mismatch.res.expected
@@ -10,13 +10,11 @@
   6 │ 
 
   Signature mismatch:
-  ...
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/gadt_constructor_signature_mismatch.res:4:3-56):
     type t<_> = Int(int): t<int> | Str(string): t<int>
-  is not included in
+  
+  Expected declaration (/.../fixtures/gadt_constructor_signature_mismatch.res:2:3-59):
     type t<_> = Int(int): t<int> | Str(string): t<string>
-  /.../fixtures/gadt_constructor_signature_mismatch.res:2:3-59:
-    Expected declaration
-  /.../fixtures/gadt_constructor_signature_mismatch.res:4:3-56:
-    Actual declaration
+  
   The types for constructor Str are not equal.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/include_extension_constructors_mismatch.res.expected b/tests/build_tests/super_errors/expected/include_extension_constructors_mismatch.res.expected
index 2866c6a589..642c1812c3 100644
--- a/tests/build_tests/super_errors/expected/include_extension_constructors_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/include_extension_constructors_mismatch.res.expected
@@ -11,21 +11,9 @@
   8 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = ..
-      type t += E(string)
-    }
-  is not included in
-    {
-      type t = ..
-      type t += E(int)
-    }
-  Extension declarations do not match:
+  
+  Actual declaration (/.../fixtures/include_extension_constructors_mismatch.res:6:13-21):
     type t += E(string)
-  is not included in
-    type t += E(int)
-  /.../fixtures/include_extension_constructors_mismatch.res:3:13-18:
-    Expected declaration
-  /.../fixtures/include_extension_constructors_mismatch.res:6:13-21:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/include_extension_constructors_mismatch.res:3:13-18):
+    type t += E(int)
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/include_missing_field.res.expected b/tests/build_tests/super_errors/expected/include_missing_field.res.expected
index 82f498a3bf..e082135a52 100644
--- a/tests/build_tests/super_errors/expected/include_missing_field.res.expected
+++ b/tests/build_tests/super_errors/expected/include_missing_field.res.expected
@@ -10,15 +10,8 @@
   7 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      let x: int
-    }
-  is not included in
-    {
-      let x: int
-      let y: string
-    }
-  The value `y` is required but not provided
-  /.../fixtures/include_missing_field.res:3:3-15:
-    Expected declaration
\ No newline at end of file
+  
+  The value `y` is required but not provided.
+  
+  Expected declaration (/.../fixtures/include_missing_field.res:3:3-15):
+    let y: string
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/include_modtype_infos_mismatch.res.expected b/tests/build_tests/super_errors/expected/include_modtype_infos_mismatch.res.expected
index 78cad63a33..63ef07d880 100644
--- a/tests/build_tests/super_errors/expected/include_modtype_infos_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/include_modtype_infos_mismatch.res.expected
@@ -12,38 +12,11 @@
   10 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      module type T = {
-        let x: string
-      }
-    }
-  is not included in
-    {
-      module type T = {
-        let x: int
-      }
-    }
-  Module type declarations do not match:
-    module type T = {
-      let x: string
-    }
-  does not match
-    module type T = {
-      let x: int
-    }
-  At position module type T = <here>
-  Modules do not match:
-    {
-      let x: string
-    }
-  is not included in
-    {
-      let x: int
-    }
-  At position module type T = <here>
-  Values do not match: let x: string is not included in let x: int
-  /.../fixtures/include_modtype_infos_mismatch.res:3:5-14:
-    Expected declaration
-  /.../fixtures/include_modtype_infos_mismatch.res:7:5-17:
-    Actual declaration
\ No newline at end of file
+  
+  In module type T:
+  
+  Actual declaration (/.../fixtures/include_modtype_infos_mismatch.res:7:5-17):
+    let x: string
+  
+  Expected declaration (/.../fixtures/include_modtype_infos_mismatch.res:3:5-14):
+    let x: int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/include_modtype_permutation.res.expected b/tests/build_tests/super_errors/expected/include_modtype_permutation.res.expected
index 411931c558..022f9a64c8 100644
--- a/tests/build_tests/super_errors/expected/include_modtype_permutation.res.expected
+++ b/tests/build_tests/super_errors/expected/include_modtype_permutation.res.expected
@@ -12,29 +12,19 @@
   12 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      module type T = {
-        let b: int
-        let a: int
-      }
-    }
-  is not included in
-    {
-      module type T = {
-        let a: int
-        let b: int
-      }
-    }
-  Module type declarations do not match:
+  
+  Actual declaration (/.../fixtures/include_modtype_permutation.res:7:15-10:3):
     module type T = {
       let b: int
       let a: int
     }
-  does not match
+  
+  Expected declaration (/.../fixtures/include_modtype_permutation.res:2:15-5:3):
     module type T = {
       let a: int
       let b: int
     }
-  At position module type T = <here>
+  
+  In module type T:
+  
   Illegal permutation of structure fields
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/include_module_types_mismatch.res.expected b/tests/build_tests/super_errors/expected/include_module_types_mismatch.res.expected
index 0542b97c80..5104390f11 100644
--- a/tests/build_tests/super_errors/expected/include_module_types_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/include_module_types_mismatch.res.expected
@@ -12,24 +12,11 @@
   14 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      module M: {
-        let a: string
-      }
-    }
-  is not included in
-    Outer
+  
   In module M:
-  Modules do not match:
-    {
-      let a: string
-    }
-  is not included in
-    Inner
-  In module M:
-  Values do not match: let a: string is not included in let a: int
-  /.../fixtures/include_module_types_mismatch.res:2:3-12:
-    Expected declaration
-  /.../fixtures/include_module_types_mismatch.res:11:9:
-    Actual declaration
\ No newline at end of file
+  
+  Actual declaration (/.../fixtures/include_module_types_mismatch.res:11:9):
+    let a: string
+  
+  Expected declaration (/.../fixtures/include_module_types_mismatch.res:2:3-12):
+    let a: int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/include_type_decl_mismatch.res.expected b/tests/build_tests/super_errors/expected/include_type_decl_mismatch.res.expected
index ab18329d62..c633d6e963 100644
--- a/tests/build_tests/super_errors/expected/include_type_decl_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/include_type_decl_mismatch.res.expected
@@ -10,19 +10,9 @@
   6 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = string
-    }
-  is not included in
-    {
-      type t = int
-    }
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/include_type_decl_mismatch.res:4:3-17):
     type t = string
-  is not included in
-    type t = int
-  /.../fixtures/include_type_decl_mismatch.res:2:3-14:
-    Expected declaration
-  /.../fixtures/include_type_decl_mismatch.res:4:3-17:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/include_type_decl_mismatch.res:2:3-14):
+    type t = int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/include_value_type_mismatch.res.expected b/tests/build_tests/super_errors/expected/include_value_type_mismatch.res.expected
index 3695d0f4c7..0585c367ae 100644
--- a/tests/build_tests/super_errors/expected/include_value_type_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/include_value_type_mismatch.res.expected
@@ -10,16 +10,9 @@
   6 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      let x: string
-    }
-  is not included in
-    {
-      let x: int
-    }
-  Values do not match: let x: string is not included in let x: int
-  /.../fixtures/include_value_type_mismatch.res:2:3-12:
-    Expected declaration
-  /.../fixtures/include_value_type_mismatch.res:4:7:
-    Actual declaration
\ No newline at end of file
+  
+  Actual declaration (/.../fixtures/include_value_type_mismatch.res:4:7):
+    let x: string
+  
+  Expected declaration (/.../fixtures/include_value_type_mismatch.res:2:3-12):
+    let x: int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/inclusion_layout_functor_parameter.res.expected b/tests/build_tests/super_errors/expected/inclusion_layout_functor_parameter.res.expected
new file mode 100644
index 0000000000..d828b9fb19
--- /dev/null
+++ b/tests/build_tests/super_errors/expected/inclusion_layout_functor_parameter.res.expected
@@ -0,0 +1,22 @@
+
+  We've found a bug for you!
+  /.../fixtures/inclusion_layout_functor_parameter.res:9:5-15:1
+
+   7 │     },
+   8 │   ) => {}
+   9 │ } = {
+  10 │   module F = (
+   . │ ...
+  14 │   ) => {}
+  15 │ }
+  16 │ 
+
+  Signature mismatch:
+  
+  In the parameter X of functor F:
+  
+  Actual declaration (/.../fixtures/inclusion_layout_functor_parameter.res:12:7-19):
+    let a: string
+  
+  Expected declaration (/.../fixtures/inclusion_layout_functor_parameter.res:6:7-16):
+    let a: int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/inclusion_layout_missing_values.res.expected b/tests/build_tests/super_errors/expected/inclusion_layout_missing_values.res.expected
new file mode 100644
index 0000000000..0b1507916c
--- /dev/null
+++ b/tests/build_tests/super_errors/expected/inclusion_layout_missing_values.res.expected
@@ -0,0 +1,24 @@
+
+  We've found a bug for you!
+  /.../fixtures/inclusion_layout_missing_values.res:7:5-9:1
+
+   5 │     let b: string
+   6 │   }
+   7 │ } = {
+   8 │   module N = {}
+   9 │ }
+  10 │ 
+
+  Signature mismatch:
+  
+  In module N:
+  
+  The value `a` is required but not provided.
+  
+  Expected declaration (/.../fixtures/inclusion_layout_missing_values.res:4:5-14):
+    let a: int
+  
+  The value `b` is required but not provided.
+  
+  Expected declaration (/.../fixtures/inclusion_layout_missing_values.res:5:5-17):
+    let b: string
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/inclusion_layout_module_kind.res.expected b/tests/build_tests/super_errors/expected/inclusion_layout_module_kind.res.expected
new file mode 100644
index 0000000000..355505c06d
--- /dev/null
+++ b/tests/build_tests/super_errors/expected/inclusion_layout_module_kind.res.expected
@@ -0,0 +1,30 @@
+
+  We've found a bug for you!
+  /.../fixtures/inclusion_layout_module_kind.res:11:5-15:1
+
+   9 │     let b: int
+  10 │   }
+  11 │ } = {
+  12 │   module F = {
+  13 │     let b = 1
+  14 │   }
+  15 │ }
+  16 │ 
+
+  Signature mismatch:
+  
+  In module F:
+  
+  Actual module type:
+    {
+      let b: int
+    }
+  
+  Expected module type:
+    (
+      X: {
+        let a: int
+      },
+    ) => {
+      let b: int
+    }
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/inclusion_layout_module_type_extra.res.expected b/tests/build_tests/super_errors/expected/inclusion_layout_module_type_extra.res.expected
new file mode 100644
index 0000000000..b28e8df492
--- /dev/null
+++ b/tests/build_tests/super_errors/expected/inclusion_layout_module_type_extra.res.expected
@@ -0,0 +1,21 @@
+
+  We've found a bug for you!
+  /.../fixtures/inclusion_layout_module_type_extra.res:7:5-12:1
+
+   5 │     let a: int
+   6 │   }
+   7 │ } = {
+   8 │   module type T = {
+   . │ ...
+  11 │   }
+  12 │ }
+  13 │ 
+
+  Signature mismatch:
+  
+  In module type T:
+  
+  The value `b` is only present in the actual declaration.
+  
+  Actual declaration (/.../fixtures/inclusion_layout_module_type_extra.res:10:5-14):
+    let b: int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/inclusion_layout_nested_module_type.res.expected b/tests/build_tests/super_errors/expected/inclusion_layout_nested_module_type.res.expected
new file mode 100644
index 0000000000..0f28b96c55
--- /dev/null
+++ b/tests/build_tests/super_errors/expected/inclusion_layout_nested_module_type.res.expected
@@ -0,0 +1,22 @@
+
+  We've found a bug for you!
+  /.../fixtures/inclusion_layout_nested_module_type.res:8:5-14:1
+
+   6 │     }
+   7 │   }
+   8 │ } = {
+   9 │   module N = {
+   . │ ...
+  13 │   }
+  14 │ }
+  15 │ 
+
+  Signature mismatch:
+  
+  In module type N.T:
+  
+  Actual declaration (/.../fixtures/inclusion_layout_nested_module_type.res:11:7-19):
+    let v: string
+  
+  Expected declaration (/.../fixtures/inclusion_layout_nested_module_type.res:5:7-16):
+    let v: int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/inline_bigint_signature_mismatch.res.expected b/tests/build_tests/super_errors/expected/inline_bigint_signature_mismatch.res.expected
index 0f6d98a703..2e85703c8f 100644
--- a/tests/build_tests/super_errors/expected/inline_bigint_signature_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/inline_bigint_signature_mismatch.res.expected
@@ -11,21 +11,9 @@
   8 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      let pos: bigint
-      let neg: bigint
-    }
-  is not included in
-    {
-      @inline(12n) let pos: bigint
-      @inline(-5n) let neg: bigint
-    }
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/inline_bigint_signature_mismatch.res:5:7-9):
     let pos: bigint
-  is not included in
-    @inline(12n) let pos: bigint
-  /.../fixtures/inline_bigint_signature_mismatch.res:2:3-30:
-    Expected declaration
-  /.../fixtures/inline_bigint_signature_mismatch.res:5:7-9:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/inline_bigint_signature_mismatch.res:2:3-30):
+    @inline(12n) let pos: bigint
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch.res.expected b/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch.res.expected
index d9ee4c1b9f..d41786140d 100644
--- a/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch.res.expected
@@ -10,20 +10,11 @@
   6 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      let f: int => int => int
-    }
-  is not included in
-    {
-      let f: (int, int) => int
-    }
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/module_sig_value_arity_mismatch.res:4:7):
     let f: int => int => int
-  is not included in
+  
+  Expected declaration (/.../fixtures/module_sig_value_arity_mismatch.res:2:3-26):
     let f: (int, int) => int
-  The implementation contains a function taking 1 argument where the interface expects one taking 2 arguments.
-  /.../fixtures/module_sig_value_arity_mismatch.res:2:3-26:
-    Expected declaration
-  /.../fixtures/module_sig_value_arity_mismatch.res:4:7:
-    Actual declaration
\ No newline at end of file
+  
+  The implementation contains a function taking 1 argument where the interface expects one taking 2 arguments.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_alias.res.expected b/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_alias.res.expected
index 66c4d574fb..5354b74ea2 100644
--- a/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_alias.res.expected
+++ b/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_alias.res.expected
@@ -10,20 +10,11 @@
   8 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      let f: curried
-    }
-  is not included in
-    {
-      let f: (int, int) => int
-    }
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/module_sig_value_arity_mismatch_alias.res:6:7):
     let f: curried
-  is not included in
+  
+  Expected declaration (/.../fixtures/module_sig_value_arity_mismatch_alias.res:4:3-26):
     let f: (int, int) => int
-  The implementation contains a function taking 1 argument where the interface expects one taking 2 arguments.
-  /.../fixtures/module_sig_value_arity_mismatch_alias.res:4:3-26:
-    Expected declaration
-  /.../fixtures/module_sig_value_arity_mismatch_alias.res:6:7:
-    Actual declaration
\ No newline at end of file
+  
+  The implementation contains a function taking 1 argument where the interface expects one taking 2 arguments.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_nested.res.expected b/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_nested.res.expected
index 6e4e8fe2a4..4b97b7168d 100644
--- a/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_nested.res.expected
+++ b/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_nested.res.expected
@@ -10,20 +10,11 @@
   6 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      let f: int => int => int => int
-    }
-  is not included in
-    {
-      let f: int => (int, int) => int
-    }
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/module_sig_value_arity_mismatch_nested.res:4:7):
     let f: int => int => int => int
-  is not included in
+  
+  Expected declaration (/.../fixtures/module_sig_value_arity_mismatch_nested.res:2:3-33):
     let f: int => (int, int) => int
-  The implementation contains a function taking 1 argument where the interface expects one taking 2 arguments.
-  /.../fixtures/module_sig_value_arity_mismatch_nested.res:2:3-33:
-    Expected declaration
-  /.../fixtures/module_sig_value_arity_mismatch_nested.res:4:7:
-    Actual declaration
\ No newline at end of file
+  
+  The implementation contains a function taking 1 argument where the interface expects one taking 2 arguments.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_reverse.res.expected b/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_reverse.res.expected
index bdc204b102..b9968ea4d2 100644
--- a/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_reverse.res.expected
+++ b/tests/build_tests/super_errors/expected/module_sig_value_arity_mismatch_reverse.res.expected
@@ -10,20 +10,11 @@
   6 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      let f: (int, int) => int
-    }
-  is not included in
-    {
-      let f: int => int => int
-    }
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/module_sig_value_arity_mismatch_reverse.res:4:7):
     let f: (int, int) => int
-  is not included in
+  
+  Expected declaration (/.../fixtures/module_sig_value_arity_mismatch_reverse.res:2:3-26):
     let f: int => int => int
-  The implementation contains a function taking 2 arguments where the interface expects one taking 1 argument.
-  /.../fixtures/module_sig_value_arity_mismatch_reverse.res:2:3-26:
-    Expected declaration
-  /.../fixtures/module_sig_value_arity_mismatch_reverse.res:4:7:
-    Actual declaration
\ No newline at end of file
+  
+  The implementation contains a function taking 2 arguments where the interface expects one taking 1 argument.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/not_undefined_functor_argument.res.expected b/tests/build_tests/super_errors/expected/not_undefined_functor_argument.res.expected
index 885a441f14..c971c01bd1 100644
--- a/tests/build_tests/super_errors/expected/not_undefined_functor_argument.res.expected
+++ b/tests/build_tests/super_errors/expected/not_undefined_functor_argument.res.expected
@@ -10,22 +10,13 @@
   12 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = option<int>
-    }
-  is not included in
-    {
-      type t
-    }
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/not_undefined_functor_argument.res:10:3-22):
     type t = option<int>
-  is not included in
+  
+  Expected declaration (/.../fixtures/not_undefined_functor_argument.res:3:19-24):
     type t
-  /.../fixtures/not_undefined_functor_argument.res:3:19-24:
-    Expected declaration
-  /.../fixtures/not_undefined_functor_argument.res:10:3-22:
-    Actual declaration
+  
   Their runtime representations differ:
-  the second declaration is @notUndefined,
-  but the first declaration can hold undefined.
\ No newline at end of file
+    Actual declaration: can hold undefined
+    Expected declaration: @notUndefined
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/not_undefined_functor_parameter.res.expected b/tests/build_tests/super_errors/expected/not_undefined_functor_parameter.res.expected
index 12957f6548..0caa1a7f97 100644
--- a/tests/build_tests/super_errors/expected/not_undefined_functor_parameter.res.expected
+++ b/tests/build_tests/super_errors/expected/not_undefined_functor_parameter.res.expected
@@ -11,19 +11,13 @@
   12 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = X.t
-    }
-  is not included in
-    {
-      type t
-    }
-  Type declarations do not match: type t = X.t is not included in type t
-  /.../fixtures/not_undefined_functor_parameter.res:7:19-24:
-    Expected declaration
-  /.../fixtures/not_undefined_functor_parameter.res:9:5-16:
-    Actual declaration
+  
+  Actual declaration (/.../fixtures/not_undefined_functor_parameter.res:9:5-16):
+    type t = X.t
+  
+  Expected declaration (/.../fixtures/not_undefined_functor_parameter.res:7:19-24):
+    type t
+  
   Their runtime representations differ:
-  the second declaration is @notUndefined,
-  but the first declaration can hold undefined.
\ No newline at end of file
+    Actual declaration: can hold undefined
+    Expected declaration: @notUndefined
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/object_manifest_set_mismatch.res.expected b/tests/build_tests/super_errors/expected/object_manifest_set_mismatch.res.expected
index a03eab7d9e..b766c08dbe 100644
--- a/tests/build_tests/super_errors/expected/object_manifest_set_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/object_manifest_set_mismatch.res.expected
@@ -10,19 +10,9 @@
   9 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = {@set "x": int}
-    }
-  is not included in
-    {
-      type t = {"x": int}
-    }
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/object_manifest_set_mismatch.res:7:3-26):
     type t = {@set "x": int}
-  is not included in
-    type t = {"x": int}
-  /.../fixtures/object_manifest_set_mismatch.res:5:3-21:
-    Expected declaration
-  /.../fixtures/object_manifest_set_mismatch.res:7:3-26:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/object_manifest_set_mismatch.res:5:3-21):
+    type t = {"x": int}
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/object_private_row_grants_set.res.expected b/tests/build_tests/super_errors/expected/object_private_row_grants_set.res.expected
index c1663dca91..7fbbe6e81d 100644
--- a/tests/build_tests/super_errors/expected/object_private_row_grants_set.res.expected
+++ b/tests/build_tests/super_errors/expected/object_private_row_grants_set.res.expected
@@ -10,19 +10,9 @@
   10 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = private {.."x": int}
-    }
-  is not included in
-    {
-      type t = private {..@set "x": int}
-    }
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/object_private_row_grants_set.res:8:3-31):
     type t = private {.."x": int}
-  is not included in
-    type t = private {..@set "x": int}
-  /.../fixtures/object_private_row_grants_set.res:6:3-36:
-    Expected declaration
-  /.../fixtures/object_private_row_grants_set.res:8:3-31:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/object_private_row_grants_set.res:6:3-36):
+    type t = private {..@set "x": int}
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/object_value_signature_set_mismatch.res.expected b/tests/build_tests/super_errors/expected/object_value_signature_set_mismatch.res.expected
index 3f040ccf3c..7751e19fab 100644
--- a/tests/build_tests/super_errors/expected/object_value_signature_set_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/object_value_signature_set_mismatch.res.expected
@@ -10,19 +10,9 @@
   11 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      let v: {@set "x": int}
-    }
-  is not included in
-    {
-      let v: {"x": int}
-    }
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/object_value_signature_set_mismatch.res:9:7):
     let v: {@set "x": int}
-  is not included in
-    let v: {"x": int}
-  /.../fixtures/object_value_signature_set_mismatch.res:7:3-19:
-    Expected declaration
-  /.../fixtures/object_value_signature_set_mismatch.res:9:7:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/object_value_signature_set_mismatch.res:7:3-19):
+    let v: {"x": int}
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/runtime_annotation_interface_over_record.res.expected b/tests/build_tests/super_errors/expected/runtime_annotation_interface_over_record.res.expected
index bc348898f4..adc91edef2 100644
--- a/tests/build_tests/super_errors/expected/runtime_annotation_interface_over_record.res.expected
+++ b/tests/build_tests/super_errors/expected/runtime_annotation_interface_over_record.res.expected
@@ -10,19 +10,13 @@
   6 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = {y: int}
-    }
-  is not included in
-    {
-      type t
-    }
-  Type declarations do not match: type t = {y: int} is not included in type t
-  /.../fixtures/runtime_annotation_interface_over_record.res:2:21-26:
-    Expected declaration
-  /.../fixtures/runtime_annotation_interface_over_record.res:4:3-19:
-    Actual declaration
+  
+  Actual declaration (/.../fixtures/runtime_annotation_interface_over_record.res:4:3-19):
+    type t = {y: int}
+  
+  Expected declaration (/.../fixtures/runtime_annotation_interface_over_record.res:2:21-26):
+    type t
+  
   Their runtime representations differ:
-  the first declaration states values whose typeof is "object",
-  the second declaration states values whose typeof is "string".
\ No newline at end of file
+    Actual declaration: typeof "object"
+    Expected declaration: typeof "string"
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/type_decl_function_arity_mismatch.res.expected b/tests/build_tests/super_errors/expected/type_decl_function_arity_mismatch.res.expected
index b1a9e86062..030e0ef4c6 100644
--- a/tests/build_tests/super_errors/expected/type_decl_function_arity_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/type_decl_function_arity_mismatch.res.expected
@@ -10,19 +10,9 @@
   6 │ 
 
   Signature mismatch:
-  Modules do not match:
-    {
-      type t = int => int => int
-    }
-  is not included in
-    {
-      type t = (int, int) => int
-    }
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/type_decl_function_arity_mismatch.res:4:3-28):
     type t = int => int => int
-  is not included in
-    type t = (int, int) => int
-  /.../fixtures/type_decl_function_arity_mismatch.res:2:3-28:
-    Expected declaration
-  /.../fixtures/type_decl_function_arity_mismatch.res:4:3-28:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/type_decl_function_arity_mismatch.res:2:3-28):
+    type t = (int, int) => int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/variant_payload_tag_mismatch.res.expected b/tests/build_tests/super_errors/expected/variant_payload_tag_mismatch.res.expected
index e012335ef1..94b27671e8 100644
--- a/tests/build_tests/super_errors/expected/variant_payload_tag_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/variant_payload_tag_mismatch.res.expected
@@ -12,13 +12,11 @@
   10 │ Console.log(
 
   Signature mismatch:
-  ...
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/variant_payload_tag_mismatch.res:6:3-56):
     type t = @as("C") A({x: int}) | @as("A") C({x: int})
-  is not included in
+  
+  Expected declaration (/.../fixtures/variant_payload_tag_mismatch.res:3:3-36):
     type t = A({x: int}) | C({x: int})
-  /.../fixtures/variant_payload_tag_mismatch.res:3:3-36:
-    Expected declaration
-  /.../fixtures/variant_payload_tag_mismatch.res:6:3-56:
-    Actual declaration
+  
   The internal representations for case A are not equal.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/expected/with_mismatch.res.expected b/tests/build_tests/super_errors/expected/with_mismatch.res.expected
index 6f5e2b4713..8e76ff2ede 100644
--- a/tests/build_tests/super_errors/expected/with_mismatch.res.expected
+++ b/tests/build_tests/super_errors/expected/with_mismatch.res.expected
@@ -9,11 +9,9 @@
 
   In this `with' constraint, the new definition of t
   does not match its original definition in the constrained signature:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/with_mismatch.res:5:29):
     type t = string
-  is not included in
-    type t = int
-  /.../fixtures/with_mismatch.res:2:3-14:
-    Expected declaration
-  /.../fixtures/with_mismatch.res:5:29:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/with_mismatch.res:2:3-14):
+    type t = int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors/fixtures/inclusion_layout_functor_parameter.res b/tests/build_tests/super_errors/fixtures/inclusion_layout_functor_parameter.res
new file mode 100644
index 0000000000..5eebab34f7
--- /dev/null
+++ b/tests/build_tests/super_errors/fixtures/inclusion_layout_functor_parameter.res
@@ -0,0 +1,15 @@
+// A difference in a functor's parameter is shown at its position in the
+// functor's type
+module M: {
+  module F: (
+    X: {
+      let a: int
+    },
+  ) => {}
+} = {
+  module F = (
+    X: {
+      let a: string
+    },
+  ) => {}
+}
diff --git a/tests/build_tests/super_errors/fixtures/inclusion_layout_missing_values.res b/tests/build_tests/super_errors/fixtures/inclusion_layout_missing_values.res
new file mode 100644
index 0000000000..152306de13
--- /dev/null
+++ b/tests/build_tests/super_errors/fixtures/inclusion_layout_missing_values.res
@@ -0,0 +1,9 @@
+// Several missing values of one module are listed under its position once
+module M: {
+  module N: {
+    let a: int
+    let b: string
+  }
+} = {
+  module N = {}
+}
diff --git a/tests/build_tests/super_errors/fixtures/inclusion_layout_module_kind.res b/tests/build_tests/super_errors/fixtures/inclusion_layout_module_kind.res
new file mode 100644
index 0000000000..f8e7d0583d
--- /dev/null
+++ b/tests/build_tests/super_errors/fixtures/inclusion_layout_module_kind.res
@@ -0,0 +1,15 @@
+// A module where a functor is expected has no declarations to compare: the
+// module types are shown
+module M: {
+  module F: (
+    X: {
+      let a: int
+    },
+  ) => {
+    let b: int
+  }
+} = {
+  module F = {
+    let b = 1
+  }
+}
diff --git a/tests/build_tests/super_errors/fixtures/inclusion_layout_module_type_extra.res b/tests/build_tests/super_errors/fixtures/inclusion_layout_module_type_extra.res
new file mode 100644
index 0000000000..aa6e215468
--- /dev/null
+++ b/tests/build_tests/super_errors/fixtures/inclusion_layout_module_type_extra.res
@@ -0,0 +1,12 @@
+// Module types must be equal: an item only the actual module type has is
+// found by comparing the other way round, and reported on the actual side
+module M: {
+  module type T = {
+    let a: int
+  }
+} = {
+  module type T = {
+    let a: int
+    let b: int
+  }
+}
diff --git a/tests/build_tests/super_errors/fixtures/inclusion_layout_nested_module_type.res b/tests/build_tests/super_errors/fixtures/inclusion_layout_nested_module_type.res
new file mode 100644
index 0000000000..318a5409d4
--- /dev/null
+++ b/tests/build_tests/super_errors/fixtures/inclusion_layout_nested_module_type.res
@@ -0,0 +1,14 @@
+// A difference in a module type inside a module is named by its path
+module M: {
+  module N: {
+    module type T = {
+      let v: int
+    }
+  }
+} = {
+  module N = {
+    module type T = {
+      let v: string
+    }
+  }
+}
diff --git a/tests/build_tests/super_errors_multi/expected/Cross_external_import_attrs.expected b/tests/build_tests/super_errors_multi/expected/Cross_external_import_attrs.expected
index aec8dbdd99..7d4e69fb96 100644
--- a/tests/build_tests/super_errors_multi/expected/Cross_external_import_attrs.expected
+++ b/tests/build_tests/super_errors_multi/expected/Cross_external_import_attrs.expected
@@ -10,13 +10,11 @@
 
   The implementation /.../fixtures/Cross_external_import_attrs/Importattrs.res
   does not match the interface /.../fixtures/Cross_external_import_attrs/importattrs.cmi:
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/Cross_external_import_attrs/Importattrs.res:1:1-2:30):
     @val @module({from: "somepkg", with: {type_: "json", \"some-identifier": "nope"}}) external data: int =
       "default"
-  is not included in
+  
+  Expected declaration (/.../fixtures/Cross_external_import_attrs/Importattrs.resi:1:1-2:30):
     @val @module({from: "somepkg", with: {type_: "json", \"some-identifier": "yep"}}) external data: int =
-      "default"
-  /.../fixtures/Cross_external_import_attrs/Importattrs.resi:1:1-2:30:
-    Expected declaration
-  /.../fixtures/Cross_external_import_attrs/Importattrs.res:1:1-2:30:
-    Actual declaration
\ No newline at end of file
+      "default"
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Cross_external_payload_name.expected b/tests/build_tests/super_errors_multi/expected/Cross_external_payload_name.expected
index 3e9460a6c9..40614fcc92 100644
--- a/tests/build_tests/super_errors_multi/expected/Cross_external_payload_name.expected
+++ b/tests/build_tests/super_errors_multi/expected/Cross_external_payload_name.expected
@@ -8,11 +8,9 @@
 
   The implementation /.../fixtures/Cross_external_payload_name/Payload.res
   does not match the interface /.../fixtures/Cross_external_payload_name/payload.cmi:
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/Cross_external_payload_name/Payload.res:1:1-39):
     @val("foo") external f: int => int = ""
-  is not included in
-    @val("bar") external f: int => int = ""
-  /.../fixtures/Cross_external_payload_name/Payload.resi:1:1-39:
-    Expected declaration
-  /.../fixtures/Cross_external_payload_name/Payload.res:1:1-39:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/Cross_external_payload_name/Payload.resi:1:1-39):
+    @val("bar") external f: int => int = ""
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Cross_external_spec_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Cross_external_spec_mismatch.expected
index e1c5e7ec51..b2e7f1072b 100644
--- a/tests/build_tests/super_errors_multi/expected/Cross_external_spec_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Cross_external_spec_mismatch.expected
@@ -8,11 +8,9 @@
 
   The implementation /.../fixtures/Cross_external_spec_mismatch/Specmismatch.res
   does not match the interface /.../fixtures/Cross_external_spec_mismatch/specmismatch.cmi:
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/Cross_external_spec_mismatch/Specmismatch.res:1:1-46):
     @val @module("m") external f: int => int = "f"
-  is not included in
-    @val external f: int => int = "f"
-  /.../fixtures/Cross_external_spec_mismatch/Specmismatch.resi:1:1-33:
-    Expected declaration
-  /.../fixtures/Cross_external_spec_mismatch/Specmismatch.res:1:1-46:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/Cross_external_spec_mismatch/Specmismatch.resi:1:1-33):
+    @val external f: int => int = "f"
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Cross_not_undefined_option_implementation.expected b/tests/build_tests/super_errors_multi/expected/Cross_not_undefined_option_implementation.expected
index efc27a4df3..efdcaf1cbd 100644
--- a/tests/build_tests/super_errors_multi/expected/Cross_not_undefined_option_implementation.expected
+++ b/tests/build_tests/super_errors_multi/expected/Cross_not_undefined_option_implementation.expected
@@ -9,14 +9,13 @@
 
   The implementation /.../fixtures/Cross_not_undefined_option_implementation/Hidden.res
   does not match the interface /.../fixtures/Cross_not_undefined_option_implementation/hidden.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Cross_not_undefined_option_implementation/Hidden.res:1:1-20):
     type t = option<int>
-  is not included in
+  
+  Expected declaration (/.../fixtures/Cross_not_undefined_option_implementation/Hidden.resi:1:15-20):
     type t
-  /.../fixtures/Cross_not_undefined_option_implementation/Hidden.resi:1:15-20:
-    Expected declaration
-  /.../fixtures/Cross_not_undefined_option_implementation/Hidden.res:1:1-20:
-    Actual declaration
+  
   Their runtime representations differ:
-  the second declaration is @notUndefined,
-  but the first declaration can hold undefined.
\ No newline at end of file
+    Actual declaration: can hold undefined
+    Expected declaration: @notUndefined
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Cross_private_abbreviation_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Cross_private_abbreviation_mismatch.expected
index 71730354d1..ee74ab2d9d 100644
--- a/tests/build_tests/super_errors_multi/expected/Cross_private_abbreviation_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Cross_private_abbreviation_mismatch.expected
@@ -10,11 +10,9 @@
 
   The implementation /.../fixtures/Cross_private_abbreviation_mismatch/Priv.res
   does not match the interface /.../fixtures/Cross_private_abbreviation_mismatch/priv.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Cross_private_abbreviation_mismatch/Priv.res:3:1-10):
     type t = b
-  is not included in
-    type t = private a
-  /.../fixtures/Cross_private_abbreviation_mismatch/Priv.resi:2:1-18:
-    Expected declaration
-  /.../fixtures/Cross_private_abbreviation_mismatch/Priv.res:3:1-10:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/Cross_private_abbreviation_mismatch/Priv.resi:2:1-18):
+    type t = private a
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Cross_private_variant_manifest_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Cross_private_variant_manifest_mismatch.expected
index 2e76d32d92..0615ae8ae3 100644
--- a/tests/build_tests/super_errors_multi/expected/Cross_private_variant_manifest_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Cross_private_variant_manifest_mismatch.expected
@@ -9,11 +9,9 @@
 
   The implementation /.../fixtures/Cross_private_variant_manifest_mismatch/Priv.res
   does not match the interface /.../fixtures/Cross_private_variant_manifest_mismatch/priv.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Cross_private_variant_manifest_mismatch/Priv.res:2:1-14):
     type w = A | B
-  is not included in
-    type w = v = private A | B
-  /.../fixtures/Cross_private_variant_manifest_mismatch/Priv.resi:2:1-26:
-    Expected declaration
-  /.../fixtures/Cross_private_variant_manifest_mismatch/Priv.res:2:1-14:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/Cross_private_variant_manifest_mismatch/Priv.resi:2:1-26):
+    type w = v = private A | B
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_claimed_by_interface.expected b/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_claimed_by_interface.expected
index 1a1ffd0059..98af76b738 100644
--- a/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_claimed_by_interface.expected
+++ b/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_claimed_by_interface.expected
@@ -8,14 +8,13 @@
 
   The implementation /.../fixtures/Cross_runtime_annotation_claimed_by_interface/Claim.res
   does not match the interface /.../fixtures/Cross_runtime_annotation_claimed_by_interface/claim.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Cross_runtime_annotation_claimed_by_interface/Claim.res:1:1-23):
     type t = option<string>
-  is not included in
+  
+  Expected declaration (/.../fixtures/Cross_runtime_annotation_claimed_by_interface/Claim.resi:1:19-24):
     type t
-  /.../fixtures/Cross_runtime_annotation_claimed_by_interface/Claim.resi:1:19-24:
-    Expected declaration
-  /.../fixtures/Cross_runtime_annotation_claimed_by_interface/Claim.res:1:1-23:
-    Actual declaration
+  
   Their runtime representations differ:
-  the first declaration states no runtime class or typeof,
-  the second declaration states values whose typeof is "string".
\ No newline at end of file
+    Actual declaration: no stated class or typeof
+    Expected declaration: typeof "string"
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_functor_argument.expected b/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_functor_argument.expected
index c2f47fb74b..b5a64b4b2d 100644
--- a/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_functor_argument.expected
+++ b/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_functor_argument.expected
@@ -9,15 +9,13 @@
   11 │ 
 
   Signature mismatch:
-  ...
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Cross_runtime_annotation_functor_argument/A_classes.res:2:20-44):
     type dog = A_classes.dog
-  is not included in
+  
+  Expected declaration (/.../fixtures/Cross_runtime_annotation_functor_argument/B_user.res:4:24-31):
     type dog
-  /.../fixtures/Cross_runtime_annotation_functor_argument/B_user.res:4:24-31:
-    Expected declaration
-  /.../fixtures/Cross_runtime_annotation_functor_argument/A_classes.res:2:20-44:
-    Actual declaration
+  
   Their runtime representations differ:
-  the first declaration states instances of Dog, a subclass of Animal,
-  the second declaration states instances of Dog.
\ No newline at end of file
+    Actual declaration: instances of Dog, a subclass of Animal
+    Expected declaration: instances of Dog
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_hidden_base.expected b/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_hidden_base.expected
index 670eba8a7d..88c413dbf4 100644
--- a/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_hidden_base.expected
+++ b/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_hidden_base.expected
@@ -9,14 +9,13 @@
 
   The implementation /.../fixtures/Cross_runtime_annotation_hidden_base/Classes.res
   does not match the interface /.../fixtures/Cross_runtime_annotation_hidden_base/classes.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Cross_runtime_annotation_hidden_base/Classes.res:2:20-44):
     type dog = private animal
-  is not included in
+  
+  Expected declaration (/.../fixtures/Cross_runtime_annotation_hidden_base/Classes.resi:2:20-44):
     type dog = private animal
-  /.../fixtures/Cross_runtime_annotation_hidden_base/Classes.resi:2:20-44:
-    Expected declaration
-  /.../fixtures/Cross_runtime_annotation_hidden_base/Classes.res:2:20-44:
-    Actual declaration
+  
   Their runtime representations differ:
-  the first declaration states instances of Dog, a subclass of Animal,
-  the second declaration states instances of Dog.
\ No newline at end of file
+    Actual declaration: instances of Dog, a subclass of Animal
+    Expected declaration: instances of Dog
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_hidden_superclass.expected b/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_hidden_superclass.expected
index 484244fad9..a45f58ed70 100644
--- a/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_hidden_superclass.expected
+++ b/tests/build_tests/super_errors_multi/expected/Cross_runtime_annotation_hidden_superclass.expected
@@ -9,14 +9,13 @@
 
   The implementation /.../fixtures/Cross_runtime_annotation_hidden_superclass/Classes.res
   does not match the interface /.../fixtures/Cross_runtime_annotation_hidden_superclass/classes.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Cross_runtime_annotation_hidden_superclass/Classes.res:2:20-44):
     type dog = private animal
-  is not included in
+  
+  Expected declaration (/.../fixtures/Cross_runtime_annotation_hidden_superclass/Classes.resi:2:20-27):
     type dog
-  /.../fixtures/Cross_runtime_annotation_hidden_superclass/Classes.resi:2:20-27:
-    Expected declaration
-  /.../fixtures/Cross_runtime_annotation_hidden_superclass/Classes.res:2:20-44:
-    Actual declaration
+  
   Their runtime representations differ:
-  the first declaration states instances of Dog, a subclass of Animal,
-  the second declaration states instances of Dog.
\ No newline at end of file
+    Actual declaration: instances of Dog, a subclass of Animal
+    Expected declaration: instances of Dog
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_constraint_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_constraint_mismatch.expected
index e8b71e2cad..ccc1d7a9d6 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_constraint_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_constraint_mismatch.expected
@@ -8,13 +8,12 @@
 
   The implementation /.../fixtures/Iface_constraint_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_constraint_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_constraint_mismatch/Foo.res:1:1-35):
     type t<'a> = 'a
-    constraint 'a = int
-  is not included in
+      constraint 'a = int
+  
+  Expected declaration (/.../fixtures/Iface_constraint_mismatch/Foo.resi:1:1-10):
     type t<'a>
-  /.../fixtures/Iface_constraint_mismatch/Foo.resi:1:1-10:
-    Expected declaration
-  /.../fixtures/Iface_constraint_mismatch/Foo.res:1:1-35:
-    Actual declaration
+  
   Their constraints differ.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_extension_constructors.expected b/tests/build_tests/super_errors_multi/expected/Iface_extension_constructors.expected
index 1b116eed3f..e8390e9d2d 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_extension_constructors.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_extension_constructors.expected
@@ -5,11 +5,9 @@
 
   The implementation /.../fixtures/Iface_extension_constructors/Foo.res
   does not match the interface /.../fixtures/Iface_extension_constructors/foo.cmi:
-  Extension declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_extension_constructors/Foo.res:4:3-16):
     type t += Boom(string)
-  is not included in
-    type t += Boom(int)
-  /.../fixtures/Iface_extension_constructors/Foo.res:
-    Expected declaration
-  /.../fixtures/Iface_extension_constructors/Foo.res:4:3-16:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/Iface_extension_constructors/Foo.resi:4:3-13):
+    type t += Boom(int)
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_field_arity_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_field_arity_mismatch.expected
index 92021a3853..0534014b39 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_field_arity_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_field_arity_mismatch.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_field_arity_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_field_arity_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_field_arity_mismatch/Foo.res:1:1-19):
     type t = A(int) | B
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_field_arity_mismatch/Foo.resi:1:1-24):
     type t = A(int, int) | B
-  /.../fixtures/Iface_field_arity_mismatch/Foo.resi:1:1-24:
-    Expected declaration
-  /.../fixtures/Iface_field_arity_mismatch/Foo.res:1:1-19:
-    Actual declaration
+  
   The arities for constructor A differ.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_field_mutable_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_field_mutable_mismatch.expected
index 1b0534cb66..77331c167a 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_field_mutable_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_field_mutable_mismatch.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_field_mutable_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_field_mutable_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_field_mutable_mismatch/Foo.res:1:1-21):
     type t = {count: int}
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_field_mutable_mismatch/Foo.resi:1:1-29):
     type t = {mutable count: int}
-  /.../fixtures/Iface_field_mutable_mismatch/Foo.resi:1:1-29:
-    Expected declaration
-  /.../fixtures/Iface_field_mutable_mismatch/Foo.res:1:1-21:
-    Actual declaration
+  
   The mutability of field count is different.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_field_names_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_field_names_mismatch.expected
index 50e347af7e..f552db4863 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_field_names_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_field_names_mismatch.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_field_names_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_field_names_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_field_names_mismatch/Foo.res:1:1-25):
     type t = {a: int, b: int}
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_field_names_mismatch/Foo.resi:1:1-25):
     type t = {x: int, y: int}
-  /.../fixtures/Iface_field_names_mismatch/Foo.resi:1:1-25:
-    Expected declaration
-  /.../fixtures/Iface_field_names_mismatch/Foo.res:1:1-25:
-    Actual declaration
+  
   Fields number 1 have different names, a and x.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_field_optional_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_field_optional_mismatch.expected
index 56261f1f0f..b504fcaede 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_field_optional_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_field_optional_mismatch.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_field_optional_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_field_optional_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_field_optional_mismatch/Foo.res:1:1-28):
     type t = {a: int, b: string}
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_field_optional_mismatch/Foo.resi:1:1-29):
     type t = {a: int, b?: string}
-  /.../fixtures/Iface_field_optional_mismatch/Foo.resi:1:1-29:
-    Expected declaration
-  /.../fixtures/Iface_field_optional_mismatch/Foo.res:1:1-28:
-    Actual declaration
+  
   The optional attribute of field b is different.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_immediate_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_immediate_mismatch.expected
index 7b6273d7c0..8de281130e 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_immediate_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_immediate_mismatch.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_immediate_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_immediate_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_immediate_mismatch/Foo.res:1:1-15):
     type t = string
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_immediate_mismatch/Foo.resi:2:1-6):
     @immediate type t
-  /.../fixtures/Iface_immediate_mismatch/Foo.resi:2:1-6:
-    Expected declaration
-  /.../fixtures/Iface_immediate_mismatch/Foo.res:1:1-15:
-    Actual declaration
-  the first is not an immediate type.
\ No newline at end of file
+  
+  the actual declaration is not an immediate type.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_kind_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_kind_mismatch.expected
index c00ea7282a..dfb3550040 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_kind_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_kind_mismatch.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_kind_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_kind_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_kind_mismatch/Foo.res:1:1-17):
     type t = {x: int}
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_kind_mismatch/Foo.resi:1:1-14):
     type t = A | B
-  /.../fixtures/Iface_kind_mismatch/Foo.resi:1:1-14:
-    Expected declaration
-  /.../fixtures/Iface_kind_mismatch/Foo.res:1:1-17:
-    Actual declaration
+  
   Their kinds differ.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_manifest_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_manifest_mismatch.expected
index 7271fca599..2ffb30d404 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_manifest_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_manifest_mismatch.expected
@@ -8,11 +8,9 @@
 
   The implementation /.../fixtures/Iface_manifest_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_manifest_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_manifest_mismatch/Foo.res:1:1-15):
     type t = string
-  is not included in
-    type t = int
-  /.../fixtures/Iface_manifest_mismatch/Foo.resi:1:1-12:
-    Expected declaration
-  /.../fixtures/Iface_manifest_mismatch/Foo.res:1:1-15:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/Iface_manifest_mismatch/Foo.resi:1:1-12):
+    type t = int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_missing_value.expected b/tests/build_tests/super_errors_multi/expected/Iface_missing_value.expected
index afd9c82554..decee53abd 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_missing_value.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_missing_value.expected
@@ -9,6 +9,8 @@
 
   The implementation /.../fixtures/Iface_missing_value/Foo.res
   does not match the interface /.../fixtures/Iface_missing_value/foo.cmi:
-  The value `b` is required but not provided
-  /.../fixtures/Iface_missing_value/Foo.resi:2:1-13:
-    Expected declaration
\ No newline at end of file
+  
+  The value `b` is required but not provided.
+  
+  Expected declaration (/.../fixtures/Iface_missing_value/Foo.resi:2:1-13):
+    let b: string
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_modtype_infos.expected b/tests/build_tests/super_errors_multi/expected/Iface_modtype_infos.expected
index 9d950c7a69..caae0f592b 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_modtype_infos.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_modtype_infos.expected
@@ -5,26 +5,11 @@
 
   The implementation /.../fixtures/Iface_modtype_infos/Foo.res
   does not match the interface /.../fixtures/Iface_modtype_infos/foo.cmi:
-  Module type declarations do not match:
-    module type T = {
-      let v: string
-    }
-  does not match
-    module type T = {
-      let v: int
-    }
-  At position module type T = <here>
-  Modules do not match:
-    {
-      let v: string
-    }
-  is not included in
-    {
-      let v: int
-    }
-  At position module type T = <here>
-  Values do not match: let v: string is not included in let v: int
-  /.../fixtures/Iface_modtype_infos/Foo.resi:2:3-12:
-    Expected declaration
-  /.../fixtures/Iface_modtype_infos/Foo.res:2:3-15:
-    Actual declaration
\ No newline at end of file
+  
+  In module type T:
+  
+  Actual declaration (/.../fixtures/Iface_modtype_infos/Foo.res:2:3-15):
+    let v: string
+  
+  Expected declaration (/.../fixtures/Iface_modtype_infos/Foo.resi:2:3-12):
+    let v: int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_module_types.expected b/tests/build_tests/super_errors_multi/expected/Iface_module_types.expected
index 09f893a162..a1feb8c6b7 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_module_types.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_module_types.expected
@@ -5,18 +5,11 @@
 
   The implementation /.../fixtures/Iface_module_types/Foo.res
   does not match the interface /.../fixtures/Iface_module_types/foo.cmi:
+  
   In module Inner:
-  Modules do not match:
-    {
-      let value: string
-    }
-  is not included in
-    {
-      let value: int
-    }
-  In module Inner:
-  Values do not match: let value: string is not included in let value: int
-  /.../fixtures/Iface_module_types/Foo.resi:2:3-16:
-    Expected declaration
-  /.../fixtures/Iface_module_types/Foo.res:2:7-11:
-    Actual declaration
\ No newline at end of file
+  
+  Actual declaration (/.../fixtures/Iface_module_types/Foo.res:2:7-11):
+    let value: string
+  
+  Expected declaration (/.../fixtures/Iface_module_types/Foo.resi:2:3-16):
+    let value: int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_privacy_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_privacy_mismatch.expected
index c8b4726a2b..1dca80df79 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_privacy_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_privacy_mismatch.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_privacy_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_privacy_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_privacy_mismatch/Foo.res:1:1-20):
     type t = private int
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_privacy_mismatch/Foo.resi:1:1-12):
     type t = int
-  /.../fixtures/Iface_privacy_mismatch/Foo.resi:1:1-12:
-    Expected declaration
-  /.../fixtures/Iface_privacy_mismatch/Foo.res:1:1-20:
-    Actual declaration
+  
   A private type would be revealed.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_record_representation_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_record_representation_mismatch.expected
index 7eb863109e..33c7164700 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_record_representation_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_record_representation_mismatch.expected
@@ -8,13 +8,12 @@
 
   The implementation /.../fixtures/Iface_record_representation_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_record_representation_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_record_representation_mismatch/Foo.res:1:1-17):
     type t = {x: int}
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_record_representation_mismatch/Foo.resi:2:1-17):
     @unboxed type t = {x: int}
-  /.../fixtures/Iface_record_representation_mismatch/Foo.resi:2:1-17:
-    Expected declaration
-  /.../fixtures/Iface_record_representation_mismatch/Foo.res:1:1-17:
-    Actual declaration
+  
   Their internal representations differ:
-  the second declaration uses unboxed representation.
\ No newline at end of file
+    The expected declaration uses unboxed representation.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_tag_name_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_tag_name_mismatch.expected
index 96795bfb81..16821fcba1 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_tag_name_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_tag_name_mismatch.expected
@@ -11,12 +11,11 @@
 
   The implementation /.../fixtures/Iface_tag_name_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_tag_name_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_tag_name_mismatch/Foo.res:2:1-4:5):
     type t = @as("a") A | B
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_tag_name_mismatch/Foo.resi:2:1-4:5):
     type t = @as("a") A | B
-  /.../fixtures/Iface_tag_name_mismatch/Foo.resi:2:1-4:5:
-    Expected declaration
-  /.../fixtures/Iface_tag_name_mismatch/Foo.res:2:1-4:5:
-    Actual declaration
+  
   Their @tag annotations differ.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_type_decl_record.expected b/tests/build_tests/super_errors_multi/expected/Iface_type_decl_record.expected
index 16ea04ada1..372f6d8dea 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_type_decl_record.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_type_decl_record.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_type_decl_record/Foo.res
   does not match the interface /.../fixtures/Iface_type_decl_record/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_type_decl_record/Foo.res:1:1-25):
     type t = {x: int, z: int}
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_type_decl_record/Foo.resi:1:1-25):
     type t = {x: int, y: int}
-  /.../fixtures/Iface_type_decl_record/Foo.resi:1:1-25:
-    Expected declaration
-  /.../fixtures/Iface_type_decl_record/Foo.res:1:1-25:
-    Actual declaration
+  
   Fields number 2 have different names, z and y.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_type_decl_variant.expected b/tests/build_tests/super_errors_multi/expected/Iface_type_decl_variant.expected
index 0805c41df8..d02d412a2e 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_type_decl_variant.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_type_decl_variant.expected
@@ -10,12 +10,11 @@
 
   The implementation /.../fixtures/Iface_type_decl_variant/Foo.res
   does not match the interface /.../fixtures/Iface_type_decl_variant/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_type_decl_variant/Foo.res:1:1-3:13):
     type t = A | B(string)
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_type_decl_variant/Foo.resi:1:1-3:10):
     type t = A | B(int)
-  /.../fixtures/Iface_type_decl_variant/Foo.resi:1:1-3:10:
-    Expected declaration
-  /.../fixtures/Iface_type_decl_variant/Foo.res:1:1-3:13:
-    Actual declaration
+  
   The types for constructor B are not equal.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_unboxed_variant_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_unboxed_variant_mismatch.expected
index 3d6d2f2df1..86d2762982 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_unboxed_variant_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_unboxed_variant_mismatch.expected
@@ -8,13 +8,12 @@
 
   The implementation /.../fixtures/Iface_unboxed_variant_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_unboxed_variant_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_unboxed_variant_mismatch/Foo.res:1:1-18):
     type t = Wrap(int)
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_unboxed_variant_mismatch/Foo.resi:2:1-18):
     @unboxed type t = Wrap(int)
-  /.../fixtures/Iface_unboxed_variant_mismatch/Foo.resi:2:1-18:
-    Expected declaration
-  /.../fixtures/Iface_unboxed_variant_mismatch/Foo.res:1:1-18:
-    Actual declaration
+  
   Their internal representations differ:
-  the second declaration uses unboxed representation.
\ No newline at end of file
+    The expected declaration uses unboxed representation.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_value_arity_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_value_arity_mismatch.expected
index 4001195e3b..f8e0555b7f 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_value_arity_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_value_arity_mismatch.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_value_arity_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_value_arity_mismatch/foo.cmi:
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/Iface_value_arity_mismatch/Foo.res:1:5):
     let f: int => int => int
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_value_arity_mismatch/Foo.resi:1:1-24):
     let f: (int, int) => int
-  The implementation contains a function taking 1 argument where the interface expects one taking 2 arguments.
-  /.../fixtures/Iface_value_arity_mismatch/Foo.resi:1:1-24:
-    Expected declaration
-  /.../fixtures/Iface_value_arity_mismatch/Foo.res:1:5:
-    Actual declaration
\ No newline at end of file
+  
+  The implementation contains a function taking 1 argument where the interface expects one taking 2 arguments.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_value_descriptions.expected b/tests/build_tests/super_errors_multi/expected/Iface_value_descriptions.expected
index 6f9df31b05..453213e6cd 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_value_descriptions.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_value_descriptions.expected
@@ -8,11 +8,9 @@
 
   The implementation /.../fixtures/Iface_value_descriptions/Foo.res
   does not match the interface /.../fixtures/Iface_value_descriptions/foo.cmi:
-  Values do not match:
+  
+  Actual declaration (/.../fixtures/Iface_value_descriptions/Foo.res:1:5-11):
     let compute: string => int
-  is not included in
-    let compute: int => int
-  /.../fixtures/Iface_value_descriptions/Foo.resi:1:1-23:
-    Expected declaration
-  /.../fixtures/Iface_value_descriptions/Foo.res:1:5-11:
-    Actual declaration
\ No newline at end of file
+  
+  Expected declaration (/.../fixtures/Iface_value_descriptions/Foo.resi:1:1-23):
+    let compute: int => int
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_variance_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_variance_mismatch.expected
index 39b96b60e2..f22b882f3f 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_variance_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_variance_mismatch.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_variance_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_variance_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_variance_mismatch/Foo.res:1:1-21):
     type t<'a> = 'a => 'a
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_variance_mismatch/Foo.resi:1:1-11):
     type t<+'a>
-  /.../fixtures/Iface_variance_mismatch/Foo.resi:1:1-11:
-    Expected declaration
-  /.../fixtures/Iface_variance_mismatch/Foo.res:1:1-21:
-    Actual declaration
+  
   Their variances do not agree.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_variant_extra_constructor.expected b/tests/build_tests/super_errors_multi/expected/Iface_variant_extra_constructor.expected
index f8d5e277de..b65115be14 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_variant_extra_constructor.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_variant_extra_constructor.expected
@@ -8,12 +8,11 @@
 
   The implementation /.../fixtures/Iface_variant_extra_constructor/Foo.res
   does not match the interface /.../fixtures/Iface_variant_extra_constructor/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_variant_extra_constructor/Foo.res:1:1-18):
     type t = A | B | C
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_variant_extra_constructor/Foo.resi:1:1-14):
     type t = A | B
-  /.../fixtures/Iface_variant_extra_constructor/Foo.resi:1:1-14:
-    Expected declaration
-  /.../fixtures/Iface_variant_extra_constructor/Foo.res:1:1-18:
-    Actual declaration
-  The constructor C is only present in the first declaration.
\ No newline at end of file
+  
+  The constructor C is only present in the actual declaration.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Iface_variant_representation_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Iface_variant_representation_mismatch.expected
index a9e569f984..8dc2f60e2a 100644
--- a/tests/build_tests/super_errors_multi/expected/Iface_variant_representation_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Iface_variant_representation_mismatch.expected
@@ -10,12 +10,11 @@
 
   The implementation /.../fixtures/Iface_variant_representation_mismatch/Foo.res
   does not match the interface /.../fixtures/Iface_variant_representation_mismatch/foo.cmi:
-  Type declarations do not match:
+  
+  Actual declaration (/.../fixtures/Iface_variant_representation_mismatch/Foo.res:1:1-3:5):
     type t = @as(0) A | B
-  is not included in
+  
+  Expected declaration (/.../fixtures/Iface_variant_representation_mismatch/Foo.resi:1:1-3:5):
     type t = @as("zero") A | B
-  /.../fixtures/Iface_variant_representation_mismatch/Foo.resi:1:1-3:5:
-    Expected declaration
-  /.../fixtures/Iface_variant_representation_mismatch/Foo.res:1:1-3:5:
-    Actual declaration
+  
   The internal representations for case A are not equal.
\ No newline at end of file
diff --git a/tests/build_tests/super_errors_multi/expected/Smoke_interface_mismatch.expected b/tests/build_tests/super_errors_multi/expected/Smoke_interface_mismatch.expected
index 96c0f47f00..5b6bfa6ab7 100644
--- a/tests/build_tests/super_errors_multi/expected/Smoke_interface_mismatch.expected
+++ b/tests/build_tests/super_errors_multi/expected/Smoke_interface_mismatch.expected
@@ -8,8 +8,9 @@
 
   The implementation /.../fixtures/Smoke_interface_mismatch/Foo.res
   does not match the interface /.../fixtures/Smoke_interface_mismatch/foo.cmi:
-  Values do not match: let v: string is not included in let v: int
-  /.../fixtures/Smoke_interface_mismatch/Foo.resi:1:1-10:
-    Expected declaration
-  /.../fixtures/Smoke_interface_mismatch/Foo.res:1:5:
-    Actual declaration
\ No newline at end of file
+  
+  Actual declaration (/.../fixtures/Smoke_interface_mismatch/Foo.res:1:5):
+    let v: string
+  
+  Expected declaration (/.../fixtures/Smoke_interface_mismatch/Foo.resi:1:1-10):
+    let v: int
\ No newline at end of file