Fixed detection of T_NULLABLE for arrow functions (ref #2708)

Author: gsherwood

src/Standards/Squiz/Tests/PHP/DisallowInlineIfUnitTest.inc

@@ -12,3 +12,5 @@ function foo(string $bar, array $baz, ?MyClass $object) : MyClass {}
 class Example {
     public ?int $scalarType;
 }
+
+$a = fn(?\DateTime $x) : ?\DateTime => $x;

src/Tokenizers/PHP.php

@@ -1073,6 +1073,7 @@ protected function tokenize($string)
                     }
 
                     if ($tokenType === T_FUNCTION
+                        || $tokenType === T_FN
                         || isset(Util\Tokens::$methodPrefixes[$tokenType]) === true
                     ) {
                         if (PHP_CODESNIFFER_VERBOSITY > 1) {
@@ -1285,6 +1286,11 @@ function return types. We want to keep the parenthesis map clean,
                 && $token[0] === T_STRING
                 && strtolower($token[1]) === 'fn'
             ) {
+                // Modify the original token stack so that
+                // future checks (like looking for T_NULLABLE) can
+                // detect the T_FN token more easily.
+                $tokens[$stackPtr][0] = T_FN;
+
                 $finalTokens[$newStackPtr] = [
                     'content' => $token[1],
                     'code'    => T_FN,
@@ -1702,8 +1708,10 @@ protected function processAdditional()
                 if ($this->tokens[$x]['code'] === T_OPEN_PARENTHESIS) {
                     $ignore  = Util\Tokens::$emptyTokens;
                     $ignore += [
-                        T_STRING => T_STRING,
-                        T_COLON  => T_COLON,
+                        T_STRING        => T_STRING,
+                        T_COLON         => T_COLON,
+                        T_NS_SEPARATOR  => T_COLON,
+                        T_NULLABLE      => T_COLON,
                     ];
 
                     $closer = $this->tokens[$x]['parenthesis_closer'];

tests/Core/Tokenizer/BackfillFnTokenTest.inc

@@ -54,3 +54,6 @@ $a = [
 
 /* testYield */
 $a = fn($x) => yield 'k' => $x;
+
+/* testNullableNamespace */
+$a = fn(?\DateTime $x) : ?\DateTime => $x;

tests/Core/Tokenizer/BackfillFnTokenTest.php

@@ -431,6 +431,34 @@ public function testYield()
     }//end testYield()
 
 
+    /**
+     * Test arrow functions that use nullable namespace types.
+     *
+     * @covers PHP_CodeSniffer\Tokenizers\PHP::processAdditional
+     *
+     * @return void
+     */
+    public function testNullableNamespace()
+    {
+        $tokens = self::$phpcsFile->getTokens();
+
+        $token = $this->getTargetToken('/* testNullableNamespace */', T_FN);
+        $this->backfillHelper($token);
+
+        $this->assertSame($tokens[$token]['scope_opener'], ($token + 15), 'Scope opener is not the arrow token');
+        $this->assertSame($tokens[$token]['scope_closer'], ($token + 18), 'Scope closer is not the semicolon token');
+
+        $opener = $tokens[$token]['scope_opener'];
+        $this->assertSame($tokens[$opener]['scope_opener'], ($token + 15), 'Opener scope opener is not the arrow token');
+        $this->assertSame($tokens[$opener]['scope_closer'], ($token + 18), 'Opener scope closer is not the semicolon token');
+
+        $closer = $tokens[$token]['scope_opener'];
+        $this->assertSame($tokens[$closer]['scope_opener'], ($token + 15), 'Closer scope opener is not the arrow token');
+        $this->assertSame($tokens[$closer]['scope_closer'], ($token + 18), 'Closer scope closer is not the semicolon token');
+
+    }//end testNullableNamespace()
+
+
     /**
      * Test that anonymous class tokens without parenthesis do not get assigned a parenthesis owner.
      *