Treat class_signature more like type_expr

Treat class_signature more like type_expr by making all its
components mutable and using three unification-like operations
for manipulating them: add_method, add_instance_variable and
inherit_class_signature. These operations behave similarly to
filter_self_method, which they replace.

We move much of the logic for handling class_signature into Btype
and Ctype and use it for the typing of class signatures
and class structures.

Instead of using method and variable tables with both identifiers and
type components as accumulators during class structure typing, we use
tables with just identifiers along with a single class_signature. This
makes the logic clearer and makes it easier to share things with the
typing of class signatures.

1 files changed, 13 insertions, 15 deletions

diff --git a/typing/types.ml b/typing/types.ml
index 0499ba6152..94028683ab 100644
--- a/typing/types.ml
+++ b/typing/types.ml
@@ -138,6 +138,7 @@ end
 module Meths = Misc.Stdlib.String.Map
 module Vars = Meths
 
+
 (* Value descriptions *)
 
 type value_description =
@@ -153,17 +154,21 @@ and value_kind =
   | Val_prim of Primitive.description   (* Primitive *)
   | Val_ivar of mutable_flag * string   (* Instance variable (mutable ?) *)
   | Val_self of
-      self_var_kind *
-      (Ident.t * mutable_flag * virtual_flag * type_expr) Vars.t *
-      string
+      class_signature * self_meths * Ident.t Vars.t * string
                                         (* Self *)
-  | Val_anc of (Ident.t * type_expr) Meths.t * string
+  | Val_anc of class_signature * Ident.t Meths.t * 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
+and self_meths =
+  | Self_concrete of Ident.t Meths.t
+  | Self_virtual of Ident.t Meths.t ref
+
+and class_signature =
+  { csig_self: type_expr;
+    mutable csig_self_row: type_expr;
+    mutable csig_vars: (mutable_flag * virtual_flag * type_expr) Vars.t;
+    mutable csig_meths: (private_flag * virtual_flag * type_expr) Meths.t;
+    mutable csig_inher: (Path.t * type_expr list) list }
 
 (* Variance *)
 
@@ -312,13 +317,6 @@ type class_type =
   | Cty_signature of class_signature
   | Cty_arrow of arg_label * type_expr * class_type
 
-and class_signature =
-  { csig_self: type_expr;
-    mutable csig_self_row: type_expr;
-    csig_vars: (mutable_flag * virtual_flag * type_expr) Vars.t;
-    mutable csig_meths: (private_flag * virtual_flag * type_expr) Meths.t;
-    csig_inher: (Path.t * type_expr list) list }
-
 type class_declaration =
   { cty_params: type_expr list;
     mutable cty_type: class_type;