Tokenizer: fix handling of namespace operator in types for arrow functions

The `namespace` keyword as an operator is perfectly valid to be used as part of a type declaration.

This usage was so far not supported in the tokenizer for the arrow function backfill.

Fixed now.

Author: jrfnl

src/Tokenizers/PHP.php

@@ -1898,6 +1898,7 @@ protected function processAdditional()
                         T_STRING       => T_STRING,
                         T_ARRAY        => T_ARRAY,
                         T_COLON        => T_COLON,
+                        T_NAMESPACE    => T_NAMESPACE,
                         T_NS_SEPARATOR => T_NS_SEPARATOR,
                         T_NULLABLE     => T_NULLABLE,
                         T_CALLABLE     => T_CALLABLE,

tests/Core/Tokenizer/BackfillFnTokenTest.inc

@@ -63,6 +63,9 @@ $a = fn($x) => yield 'k' => $x;
 /* testNullableNamespace */
 $a = fn(?\DateTime $x) : ?\DateTime => $x;
 
+/* testNamespaceOperatorInTypes */
+$fn = fn(namespace\Foo $a) : ?namespace\Foo => $a;
+
 /* testSelfReturnType */
 fn(self $a) : self => $a;
 

tests/Core/Tokenizer/BackfillFnTokenTest.php

@@ -465,6 +465,34 @@ public function testNullableNamespace()
     }//end testNullableNamespace()
 
 
+    /**
+     * Test arrow functions that use the namespace operator in the return type.
+     *
+     * @covers PHP_CodeSniffer\Tokenizers\PHP::processAdditional
+     *
+     * @return void
+     */
+    public function testNamespaceOperatorInTypes()
+    {
+        $tokens = self::$phpcsFile->getTokens();
+
+        $token = $this->getTargetToken('/* testNamespaceOperatorInTypes */', T_FN);
+        $this->backfillHelper($token);
+
+        $this->assertSame($tokens[$token]['scope_opener'], ($token + 16), 'Scope opener is not the arrow token');
+        $this->assertSame($tokens[$token]['scope_closer'], ($token + 19), 'Scope closer is not the semicolon token');
+
+        $opener = $tokens[$token]['scope_opener'];
+        $this->assertSame($tokens[$opener]['scope_opener'], ($token + 16), 'Opener scope opener is not the arrow token');
+        $this->assertSame($tokens[$opener]['scope_closer'], ($token + 19), 'Opener scope closer is not the semicolon token');
+
+        $closer = $tokens[$token]['scope_closer'];
+        $this->assertSame($tokens[$closer]['scope_opener'], ($token + 16), 'Closer scope opener is not the arrow token');
+        $this->assertSame($tokens[$closer]['scope_closer'], ($token + 19), 'Closer scope closer is not the semicolon token');
+
+    }//end testNamespaceOperatorInTypes()
+
+
     /**
      * Test arrow functions that use self/parent/callable/array/static return types.
      *