From 74ba0f68db092437a166db938cd0f2ef071296bb Mon Sep 17 00:00:00 2001
From: Nathaniel Catchpole <catch@35733.no-reply.drupal.org>
Date: Mon, 17 Sep 2018 11:37:28 +0100
Subject: [PATCH] Issue #2142107 by drunken monkey, gilsbert, David_Rothstein,
 mondrake, Kristi Wachter: Complex cloned query dependent on __toString() call

---
 .../lib/Drupal/Core/Database/Query/Select.php |  7 +++++
 .../Core/Database/SelectCloneTest.php         | 31 +++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/core/lib/Drupal/Core/Database/Query/Select.php b/core/lib/Drupal/Core/Database/Query/Select.php
index c38638a75d1..fe88f841728 100644
--- a/core/lib/Drupal/Core/Database/Query/Select.php
+++ b/core/lib/Drupal/Core/Database/Query/Select.php
@@ -914,6 +914,8 @@ class Select extends Query implements SelectInterface {
    * {@inheritdoc}
    */
   public function __clone() {
+    parent::__clone();
+
     // On cloning, also clone the dependent objects. However, we do not
     // want to clone the database connection object as that would duplicate the
     // connection itself.
@@ -923,6 +925,11 @@ class Select extends Query implements SelectInterface {
     foreach ($this->union as $key => $aggregate) {
       $this->union[$key]['query'] = clone($aggregate['query']);
     }
+    foreach ($this->tables as $alias => $table) {
+      if ($table['table'] instanceof SelectInterface) {
+        $this->tables[$alias]['table'] = clone $table['table'];
+      }
+    }
   }
 
 }
diff --git a/core/tests/Drupal/KernelTests/Core/Database/SelectCloneTest.php b/core/tests/Drupal/KernelTests/Core/Database/SelectCloneTest.php
index 30a4f1b9410..3b14283b345 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/SelectCloneTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/SelectCloneTest.php
@@ -22,6 +22,10 @@ class SelectCloneTest extends DatabaseTestBase {
     $query->condition('id', $subquery, 'IN');
 
     $clone = clone $query;
+
+    // Cloned query should have a different unique identifier.
+    $this->assertNotEquals($query->uniqueIdentifier(), $clone->uniqueIdentifier());
+
     // Cloned query should not be altered by the following modification
     // happening on original query.
     $subquery->condition('age', 25, '>');
@@ -34,4 +38,31 @@ class SelectCloneTest extends DatabaseTestBase {
     $this->assertEqual(2, $query_result, 'The query returns the expected number of rows');
   }
 
+  /**
+   * Tests that nested SELECT queries are cloned properly.
+   */
+  public function testNestedQueryCloning() {
+    $sub_query = $this->connection->select('test', 't');
+    $sub_query->addField('t', 'id', 'id');
+    $sub_query->condition('age', 28, '<');
+
+    $query = $this->connection->select($sub_query, 't');
+
+    $clone = clone $query;
+
+    // Cloned query should have a different unique identifier.
+    $this->assertNotEquals($query->uniqueIdentifier(), $clone->uniqueIdentifier());
+
+    // Cloned query should not be altered by the following modification
+    // happening on original query.
+    $sub_query->condition('age', 25, '>');
+
+    $clone_result = $clone->countQuery()->execute()->fetchField();
+    $query_result = $query->countQuery()->execute()->fetchField();
+
+    // Make sure the cloned query has not been modified.
+    $this->assertEquals(3, $clone_result, 'The cloned query returns the expected number of rows');
+    $this->assertEquals(2, $query_result, 'The query returns the expected number of rows');
+  }
+
 }