make enum constructor pattern typing more accurate

src/typing/matcher.ml

@@ -279,6 +279,7 @@ module Pattern = struct
 				let v = add_local s in
 				PatVariable v
 			| ECall(e1,el) ->
+				let t = tfun (List.map (fun _ -> mk_mono()) el) t in
 				let e1 = type_expr ctx e1 (WithType t) in
 				begin match e1.eexpr,follow e1.etype with
 					| TField(_, FEnum(en,ef)),TFun(_,TEnum(_,tl)) ->

src/typing/typer.ml

@@ -4003,6 +4003,9 @@ and maybe_type_against_enum ctx f with_type p =
 						| [t] -> loop t
 						| _ -> raise Exit
 					end
+				(* We might type against an enum constructor. *)
+				| TFun(_,tr) ->
+					loop tr
 				| _ ->
 					raise Exit
 			in

tests/misc/projects/Issue5118/compile1.hxml

@@ -0,0 +1 @@
+--display Main.hx@156@type

tests/misc/projects/Issue5118/compile1.hxml.stderr

@@ -0,0 +1,3 @@
+<type>
+v : Int -&gt; haxe.ds.Option&lt;Int&gt;
+</type>