Allow backslash in PHPDoc tag

Author: kubawerlos

src/Lexer/Lexer.php

@@ -146,7 +146,7 @@ private function generateRegexp(): string
 
 			self::TOKEN_OPEN_PHPDOC => '/\\*\\*(?=\\s)\\x20?+',
 			self::TOKEN_CLOSE_PHPDOC => '\\*/',
-			self::TOKEN_PHPDOC_TAG => '@[a-z][a-z0-9-]*+',
+			self::TOKEN_PHPDOC_TAG => '@[a-z][a-z0-9-\\\\]*+',
 			self::TOKEN_PHPDOC_EOL => '\\r?+\\n[\\x09\\x20]*+(?:\\*(?!/)\\x20?+)?',
 
 			self::TOKEN_FLOAT => '(?:-?[0-9]++\\.[0-9]*+(?:e-?[0-9]++)?)|(?:-?[0-9]*+\\.[0-9]++(?:e-?[0-9]++)?)|(?:-?[0-9]++e-?[0-9]++)',

tests/PHPStan/Parser/PhpDocParserTest.php

@@ -89,6 +89,7 @@ protected function setUp(): void
 	 * @dataProvider provideAssertTagsData
 	 * @dataProvider provideRealWorldExampleData
 	 * @dataProvider provideDescriptionWithOrWithoutHtml
+	 * @dataProvider provideTagsWithBackslash
 	 */
 	public function testParse(
 		string $label,
@@ -4459,6 +4460,20 @@ public function provideTagsWithNumbers(): Iterator
 		];
 	}
 
+	public function provideTagsWithBackslash(): Iterator
+	{
+		yield [
+			'OK without description and tag with backslash in it',
+			'/** @ORM\Mapping\Entity User */',
+			new PhpDocNode([
+				new PhpDocTagNode(
+					'@ORM\Mapping\Entity',
+					new GenericTagValueNode('User')
+				),
+			]),
+		];
+	}
+
 	/**
 	 * @dataProvider dataParseTagValue
 	 * @param PhpDocNode $expectedPhpDocNode