Avoid enum keyword BC break

Author: iluuu1994

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

@@ -0,0 +1,32 @@
+--TEST--
+Enum keyword can still be used in classes, namespaces, functions and constants
+--FILE--
+<?php
+
+namespace enum {
+    class Foo {}
+}
+
+namespace {
+    class enum {}
+
+    function enum() {
+        return 'enum function';
+    }
+
+    const enum = 'enum constant';
+
+    var_dump(new enum\Foo());
+    var_dump(new enum());
+    var_dump(enum());
+    var_dump(enum);
+}
+
+?>
+--EXPECT--
+object(enum\Foo)#1 (0) {
+}
+object(enum)#1 (0) {
+}
+string(13) "enum function"
+string(13) "enum constant"

Zend/tests/enum/keyword-whitespace.phpt

@@ -0,0 +1,16 @@
+--TEST--
+Enum keyword can be followed by arbitrary whitespaces
+--FILE--
+<?php
+
+enum A {}
+enum  B {}
+enum	C {}
+enum	 E {}
+enum
+F {}
+enum
+ G {}
+
+?>
+--EXPECT--

Zend/zend_language_scanner.l

@@ -1551,7 +1551,12 @@ NEWLINE ("\r"|"\n"|"\r\n")
 	RETURN_TOKEN_WITH_IDENT(T_TRAIT);
 }
 
-<ST_IN_SCRIPTING>"enum" {
+/*
+ * 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}[a-zA-Z_\x80-\xff] {
+	yyless(4);
 	RETURN_TOKEN_WITH_IDENT(T_ENUM);
 }