bug symfony#24189 [Yaml] parse merge keys with PARSE_OBJECT_FOR_MAP flag (xabbuh)

This PR was merged into the 3.3 branch.

Discussion
----------

[Yaml] parse merge keys with PARSE_OBJECT_FOR_MAP flag

| Q             | A
| ------------- | ---
| Branch?       | 3.3
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#24133
| License       | MIT
| Doc PR        |

Commits
-------

534eaed parse merge keys with PARSE_OBJECT_FOR_MAP flag

Author: fabpot

src/Symfony/Component/Yaml/Parser.php

@@ -249,14 +249,18 @@ private function doParse($value, $flags)
                 if ('<<' === $key) {
                     $mergeNode = true;
                     $allowOverwrite = true;
-                    if (isset($values['value']) && 0 === strpos($values['value'], '*')) {
+                    if (isset($values['value'][0]) && '*' === $values['value'][0]) {
                         $refName = substr(rtrim($values['value']), 1);
                         if (!array_key_exists($refName, $this->refs)) {
                             throw new ParseException(sprintf('Reference "%s" does not exist.', $refName), $this->getRealCurrentLineNb() + 1, $this->currentLine);
                         }
 
                         $refValue = $this->refs[$refName];
 
+                        if (Yaml::PARSE_OBJECT_FOR_MAP & $flags && $refValue instanceof \stdClass) {
+                            $refValue = (array) $refValue;
+                        }
+
                         if (!is_array($refValue)) {
                             throw new ParseException('YAML merge keys used with a scalar value instead of an array.', $this->getRealCurrentLineNb() + 1, $this->currentLine);
                         }
@@ -270,6 +274,10 @@ private function doParse($value, $flags)
                         }
                         $parsed = $this->parseBlock($this->getRealCurrentLineNb() + 1, $value, $flags);
 
+                        if (Yaml::PARSE_OBJECT_FOR_MAP & $flags && $parsed instanceof \stdClass) {
+                            $parsed = (array) $parsed;
+                        }
+
                         if (!is_array($parsed)) {
                             throw new ParseException('YAML merge keys used with a scalar value instead of an array.', $this->getRealCurrentLineNb() + 1, $this->currentLine);
                         }
@@ -279,6 +287,10 @@ private function doParse($value, $flags)
                             // and each of these nodes is merged in turn according to its order in the sequence. Keys in mapping nodes earlier
                             // in the sequence override keys specified in later mapping nodes.
                             foreach ($parsed as $parsedItem) {
+                                if (Yaml::PARSE_OBJECT_FOR_MAP & $flags && $parsedItem instanceof \stdClass) {
+                                    $parsedItem = (array) $parsedItem;
+                                }
+
                                 if (!is_array($parsedItem)) {
                                     throw new ParseException('Merge items must be arrays.', $this->getRealCurrentLineNb() + 1, $parsedItem);
                                 }
@@ -902,15 +914,15 @@ private function cleanup($value)
 
         // remove leading comments
         $trimmedValue = preg_replace('#^(\#.*?\n)+#s', '', $value, -1, $count);
-        if (1 == $count) {
+        if (1 === $count) {
             // items have been removed, update the offset
             $this->offset += substr_count($value, "\n") - substr_count($trimmedValue, "\n");
             $value = $trimmedValue;
         }
 
         // remove start of the document marker (---)
         $trimmedValue = preg_replace('#^\-\-\-.*?\n#s', '', $value, -1, $count);
-        if (1 == $count) {
+        if (1 === $count) {
             // items have been removed, update the offset
             $this->offset += substr_count($value, "\n") - substr_count($trimmedValue, "\n");
             $value = $trimmedValue;

src/Symfony/Component/Yaml/Tests/ParserTest.php

@@ -1865,6 +1865,43 @@ public function testPhpConstantTagMappingKeyWithKeysCastToStrings()
 
         $this->assertSame($expected, $this->parser->parse($yaml, Yaml::PARSE_CONSTANT | Yaml::PARSE_KEYS_AS_STRINGS));
     }
+
+    public function testMergeKeysWhenMappingsAreParsedAsObjects()
+    {
+        $yaml = <<<YAML
+foo: &FOO
+    bar: 1
+bar: &BAR
+    baz: 2
+    <<: *FOO
+baz:
+    baz_foo: 3
+    <<:
+        baz_bar: 4
+foobar:
+    bar: ~
+    <<: [*FOO, *BAR]
+YAML;
+        $expected = (object) array(
+            'foo' => (object) array(
+                'bar' => 1,
+            ),
+            'bar' => (object) array(
+                'baz' => 2,
+                'bar' => 1,
+            ),
+            'baz' => (object) array(
+                'baz_foo' => 3,
+                'baz_bar' => 4,
+            ),
+            'foobar' => (object) array(
+                'bar' => null,
+                'baz' => 2,
+            ),
+        );
+
+        $this->assertEquals($expected, $this->parser->parse($yaml, Yaml::PARSE_OBJECT_FOR_MAP));
+    }
 }
 
 class B