fix parsing negative octal numbers

Author: xabbuh

Inline.php

@@ -735,11 +735,11 @@ private static function evaluateScalar($scalar, $flags, $references = [])
             // Optimize for returning strings.
             // no break
             case '+' === $scalar[0] || '-' === $scalar[0] || '.' === $scalar[0] || is_numeric($scalar[0]):
+                if (Parser::preg_match('{^[+-]?[0-9][0-9_]*$}', $scalar)) {
+                    $scalar = str_replace('_', '', (string) $scalar);
+                }
+
                 switch (true) {
-                    case Parser::preg_match('{^[+-]?[0-9][0-9_]*$}', $scalar):
-                        $scalar = str_replace('_', '', (string) $scalar);
-                        // omitting the break / return as integers are handled in the next case
-                        // no break
                     case ctype_digit($scalar):
                         $raw = $scalar;
                         $cast = (int) $scalar;
@@ -749,7 +749,7 @@ private static function evaluateScalar($scalar, $flags, $references = [])
                         $raw = $scalar;
                         $cast = (int) $scalar;
 
-                        return '0' == $scalar[1] ? octdec($scalar) : (((string) $raw === (string) $cast) ? $cast : $raw);
+                        return '0' == $scalar[1] ? -octdec(substr($scalar, 1)) : (($raw === (string) $cast) ? $cast : $raw);
                     case is_numeric($scalar):
                     case Parser::preg_match(self::getHexRegex(), $scalar):
                         $scalar = str_replace('_', '', $scalar);

Tests/InlineTest.php

@@ -781,4 +781,20 @@ public function testUnfinishedInlineMap()
         $this->expectExceptionMessage('Unexpected end of line, expected one of ",}" at line 1 (near "{abc: \'def\'").');
         Inline::parse("{abc: 'def'");
     }
+
+    /**
+     * @dataProvider getTestsForOctalNumbers
+     */
+    public function testParseOctalNumbers($expected, $yaml)
+    {
+        self::assertSame($expected, Inline::parse($yaml));
+    }
+
+    public function getTestsForOctalNumbers()
+    {
+        return [
+            'positive octal number' => [28, '034'],
+            'negative octal number' => [-28, '-034'],
+        ];
+    }
 }