types: allow class type paths in #t

Changes

@@ -13,6 +13,10 @@ Working version
 - #6673, #1132: Relax the handling of explicit polymorphic types
   (Leo White, review by Jacques Garrigue and Gabriel Scherer)
 
+- #9232: allow any class type paths in #-types,
+  For instance, "val f: #F(X).t -> unit" is now allowed.
+  (Florian Angeletti, review by Gabriel Scherer, suggestion by Leo White)
+
 ### Runtime system:
 
 - #9119: Make [caml_stat_resize_noexc] compatible with the [realloc]

manual/manual/refman/types.etex

@@ -16,7 +16,7 @@ typexpr:
       | polymorphic-variant-type
       | '<' ['..'] '>'
       | '<' method-type { ';' method-type } [';' || ';' '..'] '>'
-      | '#' class-path
+      | '#' classtype-path
       | typexpr '#' class-path
       | '(' typexpr { ',' typexpr } ')' '#' class-path
 ;
@@ -215,17 +215,17 @@ literature) that stands for any number of extra method types.
 
 \subsubsection*{sss:typexpr-sharp-types}{\#-types}
 
-The type @'#' class-path@ is a special kind of abbreviation. This
+The type @'#' classtype-path@ is a special kind of abbreviation. This
 abbreviation unifies with the type of any object belonging to a subclass
-of class @class-path@.
+of the class type @classtype-path@.
 %
 It is handled in a special way as it usually hides a type variable (an
 ellipsis, representing the methods that may be added in a subclass).
 In particular, it vanishes when the ellipsis gets instantiated.
 %
-Each type expression @'#' class-path@ defines a new type variable, so
-type @'#' class-path '->' '#' class-path@ is usually not the same as
-type @('#' class-path 'as' "'" ident) '->' "'" ident@.
+Each type expression @'#' classtype-path@ defines a new type variable, so
+type @'#' classtype-path '->' '#' classtype-path@ is usually not the same as
+type @('#' classtype-path 'as' "'" ident) '->' "'" ident@.
 %
 
 Use of \#-types to abbreviate polymorphic variant types is deprecated.

parsing/ast_invariants.ml

@@ -47,7 +47,6 @@ let iterator =
     let loc = ty.ptyp_loc in
     match ty.ptyp_desc with
     | Ptyp_tuple ([] | [_]) -> invalid_tuple loc
-    | Ptyp_class (id, _) -> simple_longident id
     | Ptyp_package (_, cstrs) ->
       List.iter (fun (id, _) -> simple_longident id) cstrs
     | _ -> ()

parsing/parser.mly

@@ -3273,7 +3273,7 @@ atomic_type:
         { Ptyp_object ([], Closed) }
     | tys = actual_type_parameters
       HASH
-      cid = mkrhs(class_longident)
+      cid = mkrhs(clty_longident)
         { Ptyp_class(cid, tys) }
     | LBRACKET tag_field RBRACKET
         (* not row_field; see CONFLICTS *)

testsuite/tests/typing-objects/Tests.ml

@@ -66,6 +66,21 @@ and ['a] d : unit -> object constraint 'a = int #c end
 |}];;
 (* class ['a] c : unit -> object constraint 'a = int end
    and ['a] d : unit -> object constraint 'a = int #c end *)
+(* Class type constraint *)
+module F(X:sig type t end) = struct
+  class type ['a] c = object
+    method m: 'a -> X.t
+  end
+end
+class ['a] c = object
+  constraint 'a = 'a #F(Int).c
+end
+[%%expect {|
+module F :
+  functor (X : sig type t end) ->
+    sig class type ['a] c = object method m : 'a -> X.t end end
+class ['a] c : object constraint 'a = < m : 'a -> Int.t; .. > end
+|}]
 
 (* Self as parameter *)
 class ['a] c (x : 'a) = object (self : 'b)