Give more precise errors for virtual methods

Previously, the check that a non-virtual class did not
have virtual methods was delayed until the last stage of
type-checking the class. Now we do those checks more eagerly
allowing for clearer errors, especially in common cases.

1 files changed, 7 insertions, 2 deletions

diff --git a/typing/types.ml b/typing/types.ml
index 8443a770dd..1ec8f5d48f 100644
--- a/typing/types.ml
+++ b/typing/types.ml
@@ -153,13 +153,18 @@ and value_kind =
   | Val_prim of Primitive.description   (* Primitive *)
   | Val_ivar of mutable_flag * string   (* Instance variable (mutable ?) *)
   | Val_self of
-      (Ident.t * private_flag * virtual_flag * type_expr) Meths.t ref *
+      self_var_kind *
       (Ident.t * mutable_flag * virtual_flag * type_expr) Vars.t *
-      string * type_expr
+      string
                                         (* Self *)
   | Val_anc of (string * Ident.t) list * string
                                         (* Ancestor *)
 
+and self_var_kind =
+  | Self_concrete of (Ident.t * private_flag * virtual_flag * type_expr) Meths.t
+  | Self_virtual of
+      (Ident.t * private_flag * virtual_flag * type_expr) Meths.t ref * type_expr
+
 (* Variance *)
 
 module Variance = struct