Tokenizer/PHP: bug fix for missing parenthesis owner for method named "fn"

When a function is named "fn", the `function` keyword should be set as the parenthesis owner.

While this works on PHPCS 3.x, I found while making PHPCSUtils compatible with 4.x, that this was broken on PHPCS 4.x for PHP 7.2 and 7.3 since commit da0d224.

This was due to token being seen as a `T_FN` token after the initial tokenization fixing round, so the `Tokenizer::createTokenMap()` would receive the `T_FN` token and not set the parenthesis owner index.
The additional token processing run after that, would realize this is not in actual fact an arrow function and undo the retokenization (from `T_FN` back to `T_STRING`), which leaves the parentheses for this function declaration without an owner.

Fixed now by preventing the initial `T_STRING` to `T_FN` retokenization if the keyword is used in a context where the token should always be a `T_STRING`.

Author: jrfnl

src/Tokenizers/PHP.php

@@ -2217,6 +2217,8 @@ protected function tokenize($string)
             if ($tokenIsArray === true
                 && $token[0] === T_STRING
                 && strtolower($token[1]) === 'fn'
+                && isset(static::T_STRING_CONTEXTS[$finalTokens[$lastNotEmptyToken]['code']]) === false
+                && $finalTokens[$lastNotEmptyToken]['content'] !== '&'
             ) {
                 // Modify the original token stack so that
                 // future checks (like looking for T_NULLABLE) can

tests/Core/Tokenizers/Tokenizer/CreateTokenMapParenthesesTest.inc

@@ -60,8 +60,14 @@ function name($a, $b/* testFunctionParenthesesCloser */) {}
 function &returnByRef ($a, $b/* testFunctionParenthesesCloserReturnByRef */) {}
 
 class ReservedKeyword {
-    /* testFunctionParenthesesOwnerKeywordName */
-    public function match($a, $b/* testFunctionParenthesesCloserKeywordName */) {}
+    /* testFunctionParenthesesOwnerKeywordNameMatch */
+    public function match($a, $b/* testFunctionParenthesesCloserKeywordNameMatch */) {}
+
+    /* testFunctionParenthesesOwnerKeywordNameFn */
+    public function fn($a, $b/* testFunctionParenthesesCloserKeywordNameFn */) {}
+
+    /* testFunctionParenthesesOwnerKeywordNameFnReturnByRef */
+    public function &fn($a, $b/* testFunctionParenthesesCloserKeywordNameFnReturnByRef */) {}
 }
 
 /* testClosureParenthesesOwner */

tests/Core/Tokenizers/Tokenizer/CreateTokenMapParenthesesTest.php

@@ -139,8 +139,16 @@ public static function dataParenthesesWithOwner()
                 'testMarker' => '/* testFunctionParenthesesOwnerReturnByRef */',
                 'tokenCode'  => T_FUNCTION,
             ],
-            'function declaration, keyword as function name' => [
-                'testMarker' => '/* testFunctionParenthesesOwnerKeywordName */',
+            'function declaration, "match" as function name' => [
+                'testMarker' => '/* testFunctionParenthesesOwnerKeywordNameMatch */',
+                'tokenCode'  => T_FUNCTION,
+            ],
+            'function declaration, "fn" as function name'    => [
+                'testMarker' => '/* testFunctionParenthesesOwnerKeywordNameFn */',
+                'tokenCode'  => T_FUNCTION,
+            ],
+            'function declaration, "&fn" as function name'   => [
+                'testMarker' => '/* testFunctionParenthesesOwnerKeywordNameFnReturnByRef */',
                 'tokenCode'  => T_FUNCTION,
             ],
             'closure declaration'                            => [
@@ -276,7 +284,7 @@ public static function dataParenthesesWithoutOwner()
 
 
     /**
-     * Test parentheses owner tokens when used without parentheses (where possible) do *not* the "parenthesis_*" token indexes set.
+     * Test parentheses owner tokens when used without parentheses (where possible) do *not* have the "parenthesis_*" token indexes set.
      *
      * @param string     $testMarker The comment prefacing the target token.
      * @param int|string $tokenCode  The token code to look for.