Fix Longident parsing of unparenthesized dotted operators

Signed-off-by: Nathan Rebours <[email protected]>

src/longident.ml

@@ -51,10 +51,14 @@ let parse s =
   let invalid () =
     invalid_arg (Printf.sprintf "Ppxlib.Longident.parse: %S" s)
   in
-  match (String.index_opt s '(', String.rindex_opt s ')') with
-  | None, None -> parse_simple s
-  | None, _ | _, None -> invalid ()
-  | Some l, Some r -> (
+  let open_par = String.index_opt s '(' in
+  let close_par = String.index_opt s ')' in
+  let first_char_is_normal = is_normal_ident_char s.[0] in
+  match (first_char_is_normal, open_par, close_par) with
+  | false, None, None -> Lident s (* This is a raw operator, no module path *)
+  | true, None, None -> parse_simple s
+  | _, None, _ | _, _, None -> invalid ()
+  | _, Some l, Some r -> (
       if Int.(r <> String.length s - 1) then invalid ();
       let group =
         if Int.(r = l + 1) then "()"

test/base/test.ml

@@ -117,8 +117,7 @@ Exception: Invalid_argument "Ppxlib.Longident.parse: \")\"".
 (* FIXME this is a bug *)
 let _ = convert_longident "+."
 [%%expect{|
-- : string * longident =
-("( + ).", Ppxlib.Longident.Ldot (Ppxlib.Longident.Lident "+", ""))
+- : string * longident = ("( +. )", Ppxlib.Longident.Lident "+.")
 |}]
 
 let _ = convert_longident "(+.)"