Added deprecation notice when mapping keys are found in multi-line blocks

Author: guiguiboy

CHANGELOG.md

@@ -1,6 +1,11 @@
 CHANGELOG
 =========
 
+4.3.0
+-----
+
+ * Using a mapping inside a multi-line string is deprecated and will throw a `ParseException` in 5.0.
+
 4.2.0
 -----
 

Parser.php

@@ -390,6 +390,11 @@ private function doParse(string $value, int $flags)
                         if (0 === $this->offset && !$deprecatedUsage && isset($line[0]) && ' ' === $line[0]) {
                             throw new ParseException('Unable to parse.', $this->getRealCurrentLineNb() + 1, $this->currentLine, $this->filename);
                         }
+
+                        if (false !== strpos($line, ': ')) {
+                            @trigger_error('Support for mapping keys in multi-line blocks is deprecated since Symfony 4.3 and will throw a ParseException in 5.0.', E_USER_DEPRECATED);
+                        }
+
                         if ('' === trim($line)) {
                             $value .= "\n";
                         } elseif (!$previousLineWasNewline && !$previousLineWasTerminatedWithBackslash) {

Tests/ParserTest.php

@@ -525,6 +525,20 @@ public function testObjectsSupportDisabledWithExceptions()
         $this->parser->parse($yaml, Yaml::PARSE_EXCEPTION_ON_INVALID_TYPE);
     }
 
+    /**
+     * @group legacy
+     * @expectedDeprecation Support for mapping keys in multi-line blocks is deprecated since Symfony 4.3 and will throw a ParseException in 5.0.
+     */
+    public function testMappingKeyInMultiLineStringTriggersDeprecationNotice()
+    {
+        $yaml = <<<'EOF'
+data:
+    dbal:wrong
+        default_connection: monolith
+EOF;
+        $this->parser->parse($yaml);
+    }
+
     public function testCanParseContentWithTrailingSpaces()
     {
         $yaml = "items:  \n  foo: bar";