Fixed parsing of leading blank lines in folded scalars. Closes #7989.

src/Symfony/Component/Yaml/Parser.php

@@ -419,6 +419,18 @@ class Parser
             return '';
         }
 
+        $isCurrentLineBlank = $this->isCurrentLineBlank();
+        $text = '';
+
+        // leading blank lines are consumed before determining indentation
+        while ($notEOF && $isCurrentLineBlank) {
+            // newline only if not EOF
+            if ($notEOF = $this->moveToNextLine()) {
+                $text .= "\n";
+                $isCurrentLineBlank = $this->isCurrentLineBlank();
+            }
+        }
+
         // determine indentation if not specified
         if (0 === $indentation) {
             if (preg_match('/^ +/', $this->currentLine, $matches)) {
@@ -426,11 +438,9 @@ class Parser
             }
         }
 
-        $text = '';
         if ($indentation > 0) {
             $pattern = sprintf('/^ {%d}(.*)$/', $indentation);
 
-            $isCurrentLineBlank = $this->isCurrentLineBlank();
             while (
                 $notEOF && (
                     $isCurrentLineBlank ||

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

@@ -396,6 +396,27 @@ EOF;
         $this->assertSame($expected, $this->parser->parse($yaml));
     }
 
+    /**
+     * Regression test for issue #7989.
+     *
+     * @see https://github.com/symfony/symfony/issues/7989
+     */
+    public function testBlockLiteralWithLeadingNewlines()
+    {
+        $yaml = <<<'EOF'
+foo: |-
+
+
+    bar
+
+EOF;
+        $expected = array(
+            'foo' => "\n\nbar"
+        );
+
+        $this->assertSame($expected, $this->parser->parse($yaml));
+    }
+
     public function testObjectSupportEnabled()
     {
         $input = <<<EOF