Fix enum BC break where class name is followed by extends or implements

Author: iluuu1994

Zend/tests/enum/keyword-no-bc-break.phpt

@@ -7,6 +7,16 @@ namespace enum {
     class Foo {}
 }
 
+namespace foo {
+    class Bar {}
+    class enum extends Bar {}
+}
+
+namespace bar {
+    interface Baz {}
+    class enum implements Baz {}
+}
+
 namespace {
     class enum {}
 

Zend/zend_language_scanner.l

@@ -1555,6 +1555,10 @@ NEWLINE ("\r"|"\n"|"\r\n")
  * The enum keyword must be followed by whitespace and another identifier.
  * This avoids the BC break of using enum in classes, namespaces, functions and constants.
  */
+<ST_IN_SCRIPTING>"enum"{WHITESPACE}("extends"|"implements") {
+	yyless(4);
+	RETURN_TOKEN_WITH_STR(T_STRING, 0);
+}
 <ST_IN_SCRIPTING>"enum"{WHITESPACE}[a-zA-Z_\x80-\xff] {
 	yyless(4);
 	RETURN_TOKEN_WITH_IDENT(T_ENUM);