rename functions and edit error msgs

src/make/ppx_make.ml

@@ -90,9 +90,7 @@
        =
        let derived_item = create_make_fun ~loc ~ty_name ~tps label_decls in
         (match private_ with
-            (* We can't expose functions that explicitly create private 
-              records. *)
-            | Private -> []
+            | Private -> Location.raise_errorf ~loc "We cannot expose functions that explicitly create private records."
             | Public -> [ derived_item ])
      ;;
 

test/make/signature/run.t

@@ -47,3 +47,16 @@ Test 3: recursive record types
       val make_d : v:e -> w:bool -> d
       val make_e : x:int -> y:bool -> z:d -> e
     end[@@ocaml.doc "@inline"][@@merlin.hide ]
+
+Test 4: private type
+  $ test4="
+  > type f = private {
+  >   x: int ;
+  >   y: bool }[@@deriving make]"
+  $ echo "$test4" > test.mli
+  $ ./driver.exe test.mli
+  File "test.mli", line 2, characters 5-6:
+  2 | type f = private {
+           ^
+  Error: We cannot expose functions that explicitly create private records.
+  [1]

test/make/structure/run.t

@@ -87,5 +87,5 @@ Test 6: recursive types without any record types
   File "test.ml", lines 2-3, characters 0-32:
   2 | type f = int*g
   3 | and g = bool*f [@@deriving make]
-  Error: 'with fields' can only be applied on type definitions in which at least one type definition is a record
+  Error: make can only be applied on type definitions in which at least one type definition is a record.
   [1]