[pfff] support type constant definitions/declarations

Summary:
This is diff 2/2; it adds support for declaring type consts in classes. I'm
reusing some of the AST constructs for `type` and `newtype`, and wrapping
them in a new type of const declaration.

This also adds one or two `%left` precedence thingies, these seem to
give ocamlyacc the right idea about "these are not the shift/reduce
conflicts you're looking for." It takes us from 5 reported conflicts
in the grammar to just the original 1. I'll need to test this change
separately to make sure it doesn't cause sadness.

Depends on D1880752.

Test Plan:
  make tests
  # this fails if I add an intentional parse error to good_tconst_decl.php

This test case should also cover the syntax introduced in D1880752; please
let me know if something looks inadequately covered.

Will run this on www when I get to the office.

Reviewers: dominik, dreeves

Reviewed By: dreeves

Subscribers: dominik

Differential Revision: https://phabricator.fb.com/D1880760

Tasks: 6358822

Signature: t1:1880760:1425321537:0d8da37962d49d524431d9d04106c5055c8d4ed8

lang_php/analyze/foundation/ast_php_simple.ml

@@ -413,6 +413,7 @@ and type_def = {
   and type_def_kind =
   | Alias of hint_type
   | Newtype of hint_type
+  | ClassConstType of hint_type option
  (* with tarzan *)
 
 (* ------------------------------------------------------------------------- *)

lang_php/analyze/foundation/ast_php_simple_build.ml

@@ -558,6 +558,10 @@ and type_def env def =
 and type_def_kind env = function
   | Alias t -> A.Alias (hint_type env t)
   | Newtype t -> A.Newtype (hint_type env t)
+  | ClassConstType v1 -> A.ClassConstType
+    (match v1 with
+    | Some x -> Some (hint_type env x)
+    | None -> None)
 
 
 and class_def env c =
@@ -707,7 +711,7 @@ and class_body env st (mets, flds) =
     met::mets, more_flds @ flds
 
   | ClassVariables _ | ClassConstants _ | UseTrait _
-  | XhpDecl _ | TraitConstraint _
+  | XhpDecl _ | TraitConstraint _ | ClassType _
     -> (mets, flds)
 
 and method_def env m =

lang_php/analyze/foundation/database_prolog_php.ml

@@ -303,6 +303,7 @@ let visit ~add readable ast =
           )
 
         | UseTrait _ -> ()
+        | ClassType _ -> ()
         | TraitConstraint _ -> ()
         )
       | _ -> k x

lang_php/analyze/foundation/graph_code_php.ml

@@ -856,6 +856,7 @@ and type_def env def =
 
 and type_def_kind env = function
   | Alias t | Newtype t -> hint_type env t
+  | ClassConstType _t -> ()
 
 (* ---------------------------------------------------------------------- *)
 (* Types *)

lang_php/analyze/foundation/meta_ast_php_simple.ml

@@ -113,6 +113,9 @@ and vof_type_def_kind =
   | Alias v1 -> let v1 = vof_hint_type v1 in Ocaml.VSum (("Alias", [ v1 ]))
   | Newtype v1 ->
       let v1 = vof_hint_type v1 in Ocaml.VSum (("Newtype", [ v1 ]))
+  | ClassConstType v1 ->
+      let v1 = Ocaml.vof_option vof_hint_type v1 in
+        Ocaml.VSum (("ClassConstType", [v1]))
 
 and vof_case =
   function

lang_php/analyze/visual/highlight_php.ml

@@ -372,7 +372,8 @@ let visit_program ~tag _prefs  hentities (ast, toks) =
           tag info (Entity (Class, (Use2 fake_no_use2)));
          );
         k x
-      | Ast.TraitConstraint (_, _kind, _ty, _) ->
+      | Ast.TraitConstraint (_, _, _, _) 
+      | Ast.ClassType _ ->
           k x
     );
 

lang_php/matcher/php_vs_php.ml

@@ -2599,7 +2599,7 @@ and m_class_stmt a b =
         B.TraitConstraint(b1, b2, b3, b4)
       )
     ))))
-
+  | A.ClassType _, _
   | A.ClassConstants _, _
   | A.ClassVariables _, _
   | A.Method _, _

lang_php/parsing/ast_php.ml

@@ -651,7 +651,7 @@ and class_def = {
     (* facebook-ext: 'require' can appear only in traits *)
     | TraitConstraint of
         tok (* require *) * trait_constraint_kind wrap * hint_type * tok (* ; *)
-
+    | ClassType of type_def
  and class_constant = ident * static_scalar_affect option
  and class_variable = dname * static_scalar_affect option
  and class_var_modifier =
@@ -742,6 +742,7 @@ and type_def = {
   and type_def_kind =
   | Alias   of hint_type
   | Newtype of hint_type
+  | ClassConstType of hint_type option
 
 (* ------------------------------------------------------------------------- *)
 (* Other declarations *)

lang_php/parsing/map_php.ml

@@ -932,6 +932,9 @@ and map_class_stmt =
       and v3 = map_hint_type v3
       and v4 = map_tok v4
       in TraitConstraint ((v1, v2, v3, v4))
+  | ClassType ((v1)) ->
+      let v1 = map_type_def v1
+      in ClassType ((v1))
   | ClassConstants ((v1, v2, opt_ty, v3, v4)) ->
       let v1 = map_option map_tok v1
       and v2 = map_tok v2
@@ -1198,6 +1201,8 @@ and map_type_def_kind =
   function
   | Alias v1 -> let v1 = map_hint_type v1 in Alias ((v1))
   | Newtype v1 -> let v1 = map_hint_type v1 in Newtype ((v1))
+  | ClassConstType v1 ->
+    let v1 = map_option map_hint_type v1 in ClassConstType ((v1))
 
 and map_namespace_use_rule =
   function

lang_php/parsing/meta_ast_php.ml

@@ -981,6 +981,9 @@ and vof_class_stmt =
       and v3 = vof_hint_type v3
       and v4 = vof_tok v4
       in Ocaml.VSum (("TraitConstraint", [ v1; v2; v3; v4 ]))
+  | ClassType ((v1)) ->
+      let v1 = vof_type_def v1
+      in Ocaml.VSum (("ClassType", [v1]))
   | ClassConstants ((v1, v2, opt_ty, v3, v4)) ->
       let v1 = vof_option vof_tok v1
       and v2 = vof_tok v2
@@ -1273,6 +1276,8 @@ and vof_type_def_kind =
   | Alias v1 -> let v1 = vof_hint_type v1 in Ocaml.VSum (("Alias", [ v1 ]))
   | Newtype v1 ->
       let v1 = vof_hint_type v1 in Ocaml.VSum (("Newtype", [ v1 ]))
+  | ClassConstType v1 ->
+    let v1 = vof_option vof_hint_type v1 in Ocaml.VSum (("ClassConstType", [v1]))
 
 and vof_namespace_use_rule =
   function

lang_php/parsing/parser_php.mly

@@ -126,7 +126,9 @@ module PI = Parse_info
  T_SELF T_PARENT
  /*(* facebook extension *)*/
  T_TYPE T_NEWTYPE T_SHAPE
-
+%left T_TYPE
+%left T_IDENT
+%right T_ELLIPSIS
 /*(*-----------------------------------------*)*/
 /*(*2 Symbol tokens *)*/
 /*(*-----------------------------------------*)*/
@@ -688,6 +690,38 @@ class_statement:
        let const_list = [Left const] in
        ClassConstants(Some $1, $2, Some $3, const_list, $5) }
 
+/*(* facebook-ext: type constants *)*/
+ | T_ABSTRACT T_CONST T_TYPE T_IDENT T_AS type_php TSEMICOLON
+     { ClassType (* TODO (t6384084) add some fields here *) {
+         t_tok = $3;
+         t_name = Name $4;
+         t_tparams = None;
+         t_tconstraint = Some($5, $6);
+         t_tokeq = $5; (* doesn't exist here *)
+         t_kind = ClassConstType None;
+         t_sc = $7; }
+     }
+ | T_ABSTRACT T_CONST T_TYPE T_IDENT TSEMICOLON
+     { ClassType (* TODO (t6384084) add some fields here *) {
+         t_tok = $3;
+         t_name = Name $4;
+         t_tparams = None;
+         t_tconstraint = None;
+         t_tokeq = $5; (* doesn't exist here *)
+         t_kind = ClassConstType None;
+         t_sc = $5; }
+     }
+ | T_CONST T_TYPE T_IDENT type_constr_opt TEQ type_php_or_shape TSEMICOLON
+     { ClassType (* TODO (t6384084) add some fields here *) {
+         t_tok = $2;
+         t_name = Name $3;
+         t_tparams = None;
+         t_tconstraint = $4;
+         t_tokeq = $5;
+         t_kind = ClassConstType (Some $6);
+         t_sc = $7; }
+     }
+
 /*(* class constants *)*/
  | T_CONST          class_constants_declaration  TSEMICOLON
      { ClassConstants(None, $1, None, $2, $3) }

lang_php/parsing/visitor_php.ml

@@ -946,6 +946,9 @@ and v_class_stmt x =
       and v3 = v_hint_type v3
       and v4 = v_tok v4
       in ()
+  | ClassType ((v1))->
+      let v1 = v_type_def v1
+      in ()
   | ClassConstants ((v1, v2, opt_ty, v3, v4)) ->
       let v1 = v_option v_tok v1
       and v2 = v_tok v2
@@ -1146,6 +1149,7 @@ and v_type_def_kind =
   function
   | Alias v1 -> let v1 = v_hint_type v1 in ()
   | Newtype v1 -> let v1 = v_hint_type v1 in ()
+  | ClassConstType v1 -> let v1 = v_option v_hint_type v1 in ()
 and v_namespace_use_rule =
   function
   | ImportNamespace v1 -> let v1 = v_qualified_ident v1 in ()

lang_php/pretty/ast_pp_build.ml

@@ -740,6 +740,7 @@ and class_body env st acc =
   | XhpDecl _ -> acc (* TODO xhp decl *)
   | UseTrait _ -> raise (TodoConstruct "UseTrait")
   | TraitConstraint _ -> raise (TodoConstruct "TraitConstraint")
+  | ClassType _ -> raise (TodoConstruct "ConstType")
 
 and method_def env m =
   let acc = [] in

tests/php/parsing/good_tconst_decl.php

@@ -0,0 +1,66 @@
+<?hh
+abstract class A {
+  abstract const type abs_class_by_class as arraykey;
+  const type TC as arraykey = arraykey;
+
+  final public function __construct (
+    private this::abs_class_by_class $id,
+  ) {}
+
+  public function overriding(): Aint::vec {
+    return Vector {};
+  }
+
+  public function getID(): this::abs_class_by_class {
+    return $this->id;
+  }
+
+  public function testA(Aint::me::me::me::Aint $x): void {}
+}
+
+interface I {
+  abstract const type abs_class_by_class;
+}
+
+class Aint extends A {
+  const type abs_class_by_class = int;
+  const type me as Aint = Aint;
+  const type Aint = self::hop;
+  const type hop = int;
+  const type vec = ConstVector<int>;
+
+  public function test(): void {
+    $this->testA(101);
+  }
+
+  public function overriding(): ImmVector<int> {
+    return ImmVector {};
+  }
+}
+
+class Astr extends A {
+  const type abs_class_by_class = string;
+}
+
+abstract class B {
+  abstract const type AType as A;
+  abstract public static function getAID(): this::AType::abs_class_by_class;
+}
+
+class Bint extends B {
+  const type AType = Aint;
+  public static function getAID(): this::AType::abs_class_by_class {
+    return 0;
+  }
+}
+
+class Bstr extends B {
+  const type AType = Astr;
+  public static function getAID(): this::AType::abs_class_by_class {
+    return '';
+  }
+}
+
+function test(Aint $x): int {
+  return $x->getID();
+}