minor symfony#22948 [Yaml] Recommend using quotes instead of PARSE_KEYS_AS_STRINGS (GuilhemN)

This PR was squashed before being merged into the 3.4 branch (closes symfony#22948).

Discussion
----------

[Yaml] Recommend using quotes instead of PARSE_KEYS_AS_STRINGS

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | no <!-- don't forget updating src/**/CHANGELOG.md files -->
| BC breaks?    | no
| Deprecations? | yes <!-- don't forget updating UPGRADE-*.md files -->
| Tests pass?   | yes
| Fixed tickets | #... <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        |

Sorry for opening this so lately... I just realized that we could get rid of `Yaml::PARSE_KEYS_AS_STRINGS` just by recommending using quotes...

~This way we don't allow a behavior not respecting the spec and we won't need to deprecate `PARSE_KEYS_AS_STRINGS` later.~

~Is it too late for this to be merged in 3.3?~

ping @xabbuh

Commits
-------

b63c55c [Yaml] Recommend using quotes instead of PARSE_KEYS_AS_STRINGS

Author: xabbuh

UPGRADE-3.4.md

@@ -162,3 +162,30 @@ Yaml
 
  * Using the non-specific tag `!` is deprecated and will have a different
    behavior in 4.0. Use a plain integer or `!!float` instead.
+
+ * Using the `Yaml::PARSE_KEYS_AS_STRINGS` flag is deprecated as it will be
+   removed in 4.0.
+
+   Before:
+
+   ```php
+   $yaml = <<<YAML
+   null: null key
+   true: boolean true
+   2.0: float key
+   YAML;
+
+   Yaml::parse($yaml, Yaml::PARSE_KEYS_AS_STRINGS);
+   ```
+
+   After:
+
+   ```php
+   $yaml = <<<YAML
+   "null": null key
+   "true": boolean true
+   "2.0": float key
+   YAML;
+
+   Yaml::parse($yaml);
+   ```

UPGRADE-4.0.md

@@ -721,6 +721,32 @@ Yaml
    Yaml::parse($yaml);
    ```
 
+ * Removed the `Yaml::PARSE_KEYS_AS_STRINGS` flag.
+
+   Before:
+
+   ```php
+   $yaml = <<<YAML
+   null: null key
+   true: boolean true
+   2.0: float key
+   YAML;
+
+   Yaml::parse($yaml, Yaml::PARSE_KEYS_AS_STRINGS);
+   ```
+
+   After:
+
+   ```php
+   $yaml = <<<YAML
+   "null": null key
+   "true": boolean true
+   "2.0": float key
+   YAML;
+
+   Yaml::parse($yaml);
+   ```
+
  * Omitting the key of a mapping is not supported anymore and throws a `ParseException`.
 
  * Mappings with a colon (`:`) that is not followed by a whitespace are not

src/Symfony/Component/DependencyInjection/Loader/YamlFileLoader.php

@@ -609,7 +609,7 @@ protected function loadFile($file)
         }
 
         try {
-            $configuration = $this->yamlParser->parse(file_get_contents($file), Yaml::PARSE_CONSTANT | Yaml::PARSE_CUSTOM_TAGS | Yaml::PARSE_KEYS_AS_STRINGS);
+            $configuration = $this->yamlParser->parse(file_get_contents($file), Yaml::PARSE_CONSTANT | Yaml::PARSE_CUSTOM_TAGS);
         } catch (ParseException $e) {
             throw new InvalidArgumentException(sprintf('The file "%s" does not contain valid YAML.', $file), 0, $e);
         }

src/Symfony/Component/Routing/Loader/YamlFileLoader.php

@@ -17,7 +17,6 @@
 use Symfony\Component\Yaml\Exception\ParseException;
 use Symfony\Component\Yaml\Parser as YamlParser;
 use Symfony\Component\Config\Loader\FileLoader;
-use Symfony\Component\Yaml\Yaml;
 
 /**
  * YamlFileLoader loads Yaml routing files.
@@ -59,7 +58,7 @@ public function load($file, $type = null)
         }
 
         try {
-            $parsedConfig = $this->yamlParser->parse(file_get_contents($path), Yaml::PARSE_KEYS_AS_STRINGS);
+            $parsedConfig = $this->yamlParser->parse(file_get_contents($path));
         } catch (ParseException $e) {
             throw new \InvalidArgumentException(sprintf('The file "%s" does not contain valid YAML.', $path), 0, $e);
         }

src/Symfony/Component/Serializer/Mapping/Loader/YamlFileLoader.php

@@ -15,7 +15,6 @@
 use Symfony\Component\Serializer\Mapping\AttributeMetadata;
 use Symfony\Component\Serializer\Mapping\ClassMetadataInterface;
 use Symfony\Component\Yaml\Parser;
-use Symfony\Component\Yaml\Yaml;
 
 /**
  * YAML File Loader.
@@ -114,7 +113,7 @@ private function getClassesFromYaml()
             $this->yamlParser = new Parser();
         }
 
-        $classes = $this->yamlParser->parse(file_get_contents($this->file), Yaml::PARSE_KEYS_AS_STRINGS);
+        $classes = $this->yamlParser->parse(file_get_contents($this->file));
 
         if (empty($classes)) {
             return array();

src/Symfony/Component/Translation/Loader/YamlFileLoader.php

@@ -15,7 +15,6 @@
 use Symfony\Component\Translation\Exception\LogicException;
 use Symfony\Component\Yaml\Parser as YamlParser;
 use Symfony\Component\Yaml\Exception\ParseException;
-use Symfony\Component\Yaml\Yaml;
 
 /**
  * YamlFileLoader loads translations from Yaml files.
@@ -40,7 +39,7 @@ protected function loadResource($resource)
         }
 
         try {
-            $messages = $this->yamlParser->parse(file_get_contents($resource), Yaml::PARSE_KEYS_AS_STRINGS);
+            $messages = $this->yamlParser->parse(file_get_contents($resource));
         } catch (ParseException $e) {
             throw new InvalidResourceException(sprintf('Error parsing YAML, invalid file "%s"', $resource), 0, $e);
         }

src/Symfony/Component/Validator/Mapping/Loader/YamlFileLoader.php

@@ -116,7 +116,7 @@ protected function parseNodes(array $nodes)
     private function parseFile($path)
     {
         try {
-            $classes = $this->yamlParser->parse(file_get_contents($path), Yaml::PARSE_KEYS_AS_STRINGS | Yaml::PARSE_CONSTANT);
+            $classes = $this->yamlParser->parse(file_get_contents($path), Yaml::PARSE_CONSTANT);
         } catch (ParseException $e) {
             throw new \InvalidArgumentException(sprintf('The file "%s" does not contain valid YAML.', $path), 0, $e);
         }

src/Symfony/Component/Yaml/Inline.php

@@ -490,7 +490,7 @@ private static function parseMapping($mapping, $flags, &$i = 0, $references = ar
                 @trigger_error('Omitting the key of a mapping is deprecated and will throw a ParseException in 4.0.', E_USER_DEPRECATED);
             }
 
-            if (!(Yaml::PARSE_KEYS_AS_STRINGS & $flags)) {
+            if (!$isKeyQuoted) {
                 $evaluatedKey = self::evaluateScalar($key, $flags, $references);
 
                 if ('' !== $key && $evaluatedKey !== $key && !is_string($evaluatedKey) && !is_int($evaluatedKey)) {

src/Symfony/Component/Yaml/Parser.php

@@ -86,6 +86,10 @@ public function parse($value, $flags = 0)
             }
         }
 
+        if (Yaml::PARSE_KEYS_AS_STRINGS & $flags) {
+            @trigger_error('Using the Yaml::PARSE_KEYS_AS_STRINGS flag is deprecated since version 3.4 as it will be removed in 4.0. Quote your keys when they are evaluable instead.', E_USER_DEPRECATED);
+        }
+
         if (false === preg_match('//u', $value)) {
             throw new ParseException('The YAML value does not appear to be valid UTF-8.');
         }
@@ -236,7 +240,7 @@ private function doParse($value, $flags)
                     throw $e;
                 }
 
-                if (!(Yaml::PARSE_KEYS_AS_STRINGS & $flags) && !is_string($key) && !is_int($key)) {
+                if (!is_string($key) && !is_int($key)) {
                     $keyType = is_numeric($key) ? 'numeric key' : 'non-string key';
                     @trigger_error(sprintf('Implicit casting of %s to string is deprecated since version 3.3 and will throw \Symfony\Component\Yaml\Exception\ParseException in 4.0. Quote your evaluable mapping keys instead.', $keyType), E_USER_DEPRECATED);
                 }

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

@@ -125,7 +125,7 @@ public function testSpecifications()
                     // TODO
                 } else {
                     eval('$expected = '.trim($test['php']).';');
-                    $this->assertSame($expected, $this->parser->parse($this->dumper->dump($expected, 10), Yaml::PARSE_KEYS_AS_STRINGS), $test['test']);
+                    $this->assertSame($expected, $this->parser->parse($this->dumper->dump($expected, 10)), $test['test']);
                 }
             }
         }