hphp/hack/src/typing/tast_check/tautology_check.ml

   1 (**
   2  * Copyright (c) 2018, Facebook, Inc.
   3  * All rights reserved.
   4  *
   5  * This source code is licensed under the MIT license found in the
   6  * LICENSE file in the "hack" directory of this source tree.
   7  *
   8  *)
   9
  10 [@@@warning "-33"]
  11 open Core_kernel
  12 [@@@warning "+33"]
  13 open Ast_defs
  14 open Tast
  15
  16 let trivial_equality_check p bop env ((_, ty1), _ as te1 : expr) ((_, ty2), _ as te2 : expr) =
  17   begin match te1, te2 with
  18   | (_, Null), ((_, ty), _) | ((_, ty), _), (_, Null) ->
  19     Tast_env.assert_nullable p bop env ty
  20   | _ -> ()
  21   end;
  22   Tast_env.assert_nontrivial p bop env ty1 ty2
  23
  24 let handler = object
  25   inherit Tast_visitor.handler_base
  26
  27   method! at_expr env = function
  28     | (p, _), Binop ((Eqeqeq | Diff2) as bop, te1, te2) ->
  29       trivial_equality_check p bop env te1 te2
  30     | _ -> ()
  31 end