Error at classname variables in class member accesses and new

Summary: specifically, we warn against a `classname<_>` $c in `$c::f()`, `$c::X`, `$c::$x` and `new $c()`

Reviewed By: vassilmladenov

Differential Revision: D69555473

fbshipit-source-id: 7af548f1022d8d16b0d929281c38494d29de843b

Author: chenmillie

hphp/hack/src/errors/error_codes.ml

@@ -777,6 +777,7 @@ module Typing = struct
     | InvalidRecursiveType [@value 4485]
     | StaticCallOnTraitRequireThisAs [@value 4486]
     | NeedsConcreteOverride [@value 4487]
+    | StringToClassPointer [@value 4488]
   (* Add new Typing codes here! Comment out when deprecating. *)
   [@@deriving enum, show { with_path = false }]
 

hphp/hack/src/oxidized/gen/error_codes.rs

@@ -3,7 +3,7 @@
 // This source code is licensed under the MIT license found in the
 // LICENSE file in the "hack" directory of this source tree.
 //
-// @generated SignedSource<<e55393123a98a4ee390186d6e756757f>>
+// @generated SignedSource<<e88a2f294b10a0e898cef421d353cb08>>
 //
 // To regenerate this file, run:
 //   hphp/hack/src/oxidized_regen.sh
@@ -601,6 +601,7 @@ pub enum Typing {
     InvalidRecursiveType = 4485,
     StaticCallOnTraitRequireThisAs = 4486,
     NeedsConcreteOverride = 4487,
+    StringToClassPointer = 4488,
 }
 impl TrivialDrop for Typing {}
 arena_deserializer::impl_deserialize_in_arena!(Typing);

hphp/hack/src/typing/typing.ml

@@ -10049,7 +10049,20 @@ end = struct
         | (_, Tnewtype (classname, [the_cls], as_ty))
           when String.equal classname SN.Classes.cClassname ->
           let wrap ty = mk (Reason.none, Tnewtype (classname, [ty], as_ty)) in
-          resolve_class_pointer env wrap the_cls
+          let ((env, ty_err), (ty, err_res)) =
+            resolve_class_pointer env wrap the_cls
+          in
+          let cls_name =
+            Typing_print.full_strip_ns ~hide_internals:true env ty
+          in
+          Typing_class_pointers.error_at_classname_type
+            env
+            (TypecheckerOptions.class_pointer_level
+               (Env.get_tcopt env)
+               "classname_class")
+            p
+            cls_name;
+          ((env, ty_err), (ty, err_res))
         | (_, Tclass_ptr the_cls) ->
           let wrap ty = mk (Reason.none, Tclass_ptr ty) in
           resolve_class_pointer env wrap the_cls

hphp/hack/src/typing/typing_class_pointers.ml

@@ -32,6 +32,13 @@ let error_at_cls_ptr_type env level pos ty =
       Typing_error.(primary @@ Primary.Class_pointer_to_string { pos; ty })
   | _ -> ()
 
+let error_at_classname_type env level pos cls_name =
+  if level > 1 then
+    Typing_error_utils.add_typing_error
+      ~env
+      Typing_error.(
+        primary @@ Primary.String_to_class_pointer { pos; cls_name })
+
 let string_of_class_id_ = function
   | CIparent -> "parent"
   | CIself -> "self"

hphp/hack/src/typing/typing_error.ml

@@ -1359,6 +1359,10 @@ module Primary = struct
         pos: Pos.t;
         ty: string;
       }
+    | String_to_class_pointer of {
+        pos: Pos.t;
+        cls_name: string;
+      }
     | Optional_parameter_not_supported of Pos.t
     | Optional_parameter_not_abstract of Pos.t
   [@@deriving show]

hphp/hack/src/typing/typing_error.mli

@@ -1335,6 +1335,10 @@ module Primary : sig
         pos: Pos.t;
         ty: string;
       }
+    | String_to_class_pointer of {
+        pos: Pos.t;
+        cls_name: string;
+      }
     | Optional_parameter_not_supported of Pos.t
     | Optional_parameter_not_abstract of Pos.t
   [@@deriving show]

hphp/hack/src/typing/typing_error_utils.ml

@@ -5520,6 +5520,25 @@ end = struct
       [],
       User_error_flags.empty )
 
+  let string_to_class_pointer pos cls_name =
+    let cls_name = Utils.strip_ns cls_name in
+    let classname_ty = Printf.sprintf "classname<%s>" cls_name in
+    let classname_ty_md = Markdown_lite.md_codify classname_ty in
+    let class_ptr_ty = Printf.sprintf "class<%s>" cls_name in
+    let class_ptr_ty_md = Markdown_lite.md_codify class_ptr_ty in
+    ( Error_code.ClassPointerToString,
+      lazy
+        ( pos,
+          "It is no longer allowed to use a "
+          ^ classname_ty_md
+          ^ " in this position. Please use a "
+          ^ class_ptr_ty_md
+          ^ " instead." ),
+      lazy [],
+      lazy Explanation.empty,
+      [],
+      User_error_flags.empty )
+
   let to_error t ~env : error =
     let open Typing_error.Primary in
     match t with
@@ -6105,6 +6124,8 @@ end = struct
     | Class_const_to_string { pos; cls_name } ->
       class_const_to_string pos cls_name
     | Class_pointer_to_string { pos; ty } -> class_pointer_to_string pos ty
+    | String_to_class_pointer { pos; cls_name } ->
+      string_to_class_pointer pos cls_name
     | Optional_parameter_not_supported pos ->
       optional_parameter_not_supported pos
     | Optional_parameter_not_abstract pos -> optional_parameter_not_abstract pos

hphp/hack/test/typecheck/class_pointers/HH_FLAGS

@@ -1 +1 @@
---config 'class_pointer_levels={"param": 2, "return": 2, "prop": 2, "concat": 2, "const": 2, "enum": 2, "arraykey": 3}'
+--config 'class_pointer_levels={"param": 2, "return": 2, "prop": 2, "concat": 2, "const": 2, "enum": 2, "arraykey": 3, "classname_class": 2}'

hphp/hack/test/typecheck/class_pointers/typing_error_classname.php

@@ -0,0 +1,17 @@
+<?hh
+
+<<__ConsistentConstruct>>
+class A {
+  const string CNS = "X";
+  public static int $prop = 42;
+  public static function meth(): void {}
+}
+
+class B extends A {
+  public function test(classname<A> $a): void {
+    $a::meth();
+    $a::CNS;
+    $a::$prop;
+    new $a();
+  }
+}

hphp/hack/test/typecheck/class_pointers/typing_error_classname.php.class_pointer.exp

@@ -0,0 +1,8 @@
+ERROR: File "typing_error_classname.php", line 12, characters 5-6:
+It is no longer allowed to use a `classname<A>` in this position. Please use a `class<A>` instead. (Typing[4482])
+ERROR: File "typing_error_classname.php", line 13, characters 5-6:
+It is no longer allowed to use a `classname<A>` in this position. Please use a `class<A>` instead. (Typing[4482])
+ERROR: File "typing_error_classname.php", line 14, characters 5-6:
+It is no longer allowed to use a `classname<A>` in this position. Please use a `class<A>` instead. (Typing[4482])
+ERROR: File "typing_error_classname.php", line 15, characters 9-10:
+It is no longer allowed to use a `classname<A>` in this position. Please use a `class<A>` instead. (Typing[4482])