hphp/hack/test/typecheck/finally_typing.php

   1 <?hh // partial
   2 /**
   3  * Copyright (c) 2014, Facebook, Inc.
   4  * All rights reserved.
   5  *
   6  * This source code is licensed under the MIT license found in the
   7  * LICENSE file in the "hack" directory of this source tree.
   8  *
   9  *
  10  */
  11
  12 function finally_typing1(): string {
  13   $a = 23;
  14   try {
  15     do_something();
  16   } finally {
  17     $a = 'string'; // this definition escapes the clause
  18   }
  19   return $a;
  20 }
  21
  22 function finally_typing2(): string {
  23   $a = 23;
  24   try {
  25     do_something();
  26     return 'string';
  27   } finally {
  28     // this definition escapes the clause, even with terminality
  29     $a = 'string';
  30   }
  31   return $a;
  32 }
  33
  34 // with a different story with respect to unreachable code ...
  35 // function finally_typing3(): int {
  36 //   $a = 23;
  37 //   try {
  38 //     do_something();
  39 //     $a = 25;
  40 //     return $a; // terminal block
  41 //   } finally {
  42 //     // this assignment beats out the original, but it doesn't matter
  43 //     // because the try is fully terminal
  44 //     $a = 'string';
  45 //   }
  46 //   return $a;
  47 // }
  48
  49 function do_something(): void {}
  50
  51 function finally_typing3(bool $c): int {
  52   try {
  53     try {
  54       if ($c) {
  55         $a = "string";
  56         throw new Exception();
  57       }
  58       $a = 0;
  59     } finally {
  60       // $a has different types depending on the continuation
  61       $b = $a;
  62     }
  63   } catch (Exception $_) {
  64     // $b should be a string here
  65     return str_to_int($b);
  66   }
  67   return $b;
  68 }
  69
  70 function str_to_int(string $s): int {
  71   return 0;
  72 }
  73
  74 function finally_typing4(int $x): void {
  75   $a = 0;
  76   try {
  77     try {
  78       if ($x < 0) {
  79         throw new Exception();
  80       }
  81     } finally {
  82       if ($x < 1) {
  83         $a = "string";
  84         throw new Exception();
  85       }
  86       $a = 1;
  87     }
  88   } catch (Exception $_) {
  89     hh_show($a);
  90     return;
  91   }
  92   hh_show($a);
  93 }