From fb83da94bd7833ae9b25f7062d3cbe522c2fd9d7 Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Tue, 8 Jan 2019 09:02:41 -0500
Subject: [PATCH] Exit early when encountering complicated conditionals

---
 .../ComplicatedExpressionException.php        |  6 ++
 src/Psalm/Type/Algebra.php                    | 30 ++++++++--
 tests/TypeAlgebraTest.php                     | 58 +++++++++++++++++++
 3 files changed, 88 insertions(+), 6 deletions(-)
 create mode 100644 src/Psalm/Exception/ComplicatedExpressionException.php

diff --git a/src/Psalm/Exception/ComplicatedExpressionException.php b/src/Psalm/Exception/ComplicatedExpressionException.php
new file mode 100644
index 000000000..deaf37404
--- /dev/null
+++ b/src/Psalm/Exception/ComplicatedExpressionException.php
@@ -0,0 +1,6 @@
+<?php
+namespace Psalm\Exception;
+
+class ComplicatedExpressionException extends \Exception
+{
+}
diff --git a/src/Psalm/Type/Algebra.php b/src/Psalm/Type/Algebra.php
index 66566ecd3..5718974ae 100644
--- a/src/Psalm/Type/Algebra.php
+++ b/src/Psalm/Type/Algebra.php
@@ -3,6 +3,7 @@ namespace Psalm\Type;
 
 use PhpParser;
 use Psalm\Codebase;
+use Psalm\Exception\ComplicatedExpressionException;
 use Psalm\Internal\Analyzer\Statements\Expression\AssertionFinder;
 use Psalm\Internal\Clause;
 use Psalm\CodeLocation;
@@ -12,6 +13,9 @@ use Psalm\Type\Algebra;
 
 class Algebra
 {
+    /** @var int */
+    private static $clause_count = 0;
+
     /**
      * @param  array<string, array<int, array<int, string>>>  $all_types
      *
@@ -342,8 +346,8 @@ class Algebra
      */
     private static function groupImpossibilities(array $clauses)
     {
-        if (count($clauses) > 5000) {
-            return [];
+        if (static::$clause_count > 500) {
+            throw new ComplicatedExpressionException();
         }
 
         $clause = array_shift($clauses);
@@ -353,8 +357,8 @@ class Algebra
         if ($clauses) {
             $grouped_clauses = self::groupImpossibilities($clauses);
 
-            if (count($grouped_clauses) > 5000) {
-                return [];
+            if (static::$clause_count > 500) {
+                throw new ComplicatedExpressionException();
             }
 
             foreach ($grouped_clauses as $grouped_clause) {
@@ -375,6 +379,8 @@ class Algebra
                         $new_clause = new Clause($new_clause_possibilities, false, true, true);
 
                         $new_clauses[] = $new_clause;
+
+                        self::$clause_count++;
                     }
                 }
             }
@@ -388,6 +394,8 @@ class Algebra
                     $new_clause = new Clause([$var => [$impossible_type]]);
 
                     $new_clauses[] = $new_clause;
+
+                    self::$clause_count++;
                 }
             }
         }
@@ -500,12 +508,22 @@ class Algebra
      */
     public static function negateFormula(array $clauses)
     {
+        if (count($clauses) > 1000) {
+            return [];
+        }
+
+        self::$clause_count = 0;
+
         foreach ($clauses as $clause) {
             self::calculateNegation($clause);
         }
 
-        $negated = self::simplifyCNF(self::groupImpossibilities($clauses));
-        return $negated;
+        try {
+            $negated = self::simplifyCNF(self::groupImpossibilities($clauses));
+            return $negated;
+        } catch (ComplicatedExpressionException $e) {
+            return [];
+        }
     }
 
     /**
diff --git a/tests/TypeAlgebraTest.php b/tests/TypeAlgebraTest.php
index cc0598f5f..6745785b5 100644
--- a/tests/TypeAlgebraTest.php
+++ b/tests/TypeAlgebraTest.php
@@ -826,6 +826,64 @@ class TypeAlgebraTest extends TestCase
                     $array = [$x => 2];
                     echo $array["_a"];',
             ],
+            'noMemoryIssueWithLongConditional' => [
+                '<?php
+
+                function foo(int $c) : string {
+                    if (!($c >= 0x5be && $c <= 0x10b7f)) {
+                        return "LTR";
+                    }
+
+                    if ($c <= 0x85e) {
+                        if ($c === 0x5be ||
+                            $c === 0x5c0 ||
+                            $c === 0x5c3 ||
+                            $c === 0x5c6 ||
+                            ($c >= 0x5d0 && $c <= 0x5ea) ||
+                            ($c >= 0x5f0 && $c <= 0x5f4) ||
+                            $c === 0x608 ||
+                            ($c >= 0x712 && $c <= 0x72f) ||
+                            ($c >= 0x74d && $c <= 0x7a5) ||
+                            $c === 0x7b1 ||
+                            ($c >= 0x7c0 && $c <= 0x7ea) ||
+                            ($c >= 0x7f4 && $c <= 0x7f5) ||
+                            $c === 0x7fa ||
+                            ($c >= 0x800 && $c <= 0x815) ||
+                            $c === 0x81a ||
+                            $c === 0x824 ||
+                            $c === 0x828 ||
+                            ($c >= 0x830 && $c <= 0x83e) ||
+                            ($c >= 0x840 && $c <= 0x858) ||
+                            $c === 0x85e
+                        ) {
+                            return "RTL";
+                        }
+                    } elseif ($c === 0x200f) {
+                        return "RTL";
+                    } elseif ($c >= 0xfb1d) {
+                        if ($c === 0xfb1d ||
+                            ($c >= 0xfb1f && $c <= 0xfb28) ||
+                            ($c >= 0xfb2a && $c <= 0xfb36) ||
+                            ($c >= 0xfb38 && $c <= 0xfb3c) ||
+                            $c === 0xfb3e ||
+                            ($c >= 0x10a10 && $c <= 0x10a13) ||
+                            ($c >= 0x10a15 && $c <= 0x10a17) ||
+                            ($c >= 0x10a19 && $c <= 0x10a33) ||
+                            ($c >= 0x10a40 && $c <= 0x10a47) ||
+                            ($c >= 0x10a50 && $c <= 0x10a58) ||
+                            ($c >= 0x10a60 && $c <= 0x10a7f) ||
+                            ($c >= 0x10b00 && $c <= 0x10b35) ||
+                            ($c >= 0x10b40 && $c <= 0x10b55) ||
+                            ($c >= 0x10b58 && $c <= 0x10b72) ||
+                            ($c >= 0x10b78 && $c <= 0x10b7f)
+                        ) {
+                            return "RTL";
+                        }
+                    }
+
+                    return "LTR";
+                }'
+            ],
         ];
     }