PHP 8.5 | Tokenizer/PHP: properly fix "Using null as an array offset" deprecation

src/Tokenizers/PHP.php

@@ -2244,6 +2244,24 @@ protected function tokenize($string)
                     break;
                 }//end for
 
+                // Handle live coding/parse errors elegantly.
+                // If the "?" is the last non-empty token in the file, we cannot draw a definitive conclusion,
+                // so tokenize as T_INLINE_THEN.
+                if ($i === $numTokens) {
+                    if (PHP_CODESNIFFER_VERBOSITY > 1) {
+                        echo "\t\t* token $stackPtr at end of file changed from ? to T_INLINE_THEN".PHP_EOL;
+                    }
+
+                    $newToken['code'] = T_INLINE_THEN;
+                    $newToken['type'] = 'T_INLINE_THEN';
+
+                    $insideInlineIf[] = $stackPtr;
+
+                    $finalTokens[$newStackPtr] = $newToken;
+                    $newStackPtr++;
+                    continue;
+                }
+
                 /*
                  * This can still be a nullable type or a ternary.
                  * Do additional checking.
@@ -2253,6 +2271,11 @@ protected function tokenize($string)
                 $lastSeenNonEmpty = null;
 
                 for ($i = ($stackPtr - 1); $i >= 0; $i--) {
+                    if (isset($tokens[$i]) === false) {
+                        // Ignore skipped tokens (related to PHP 8+ slash/hash comment vs new line retokenization).
+                        continue;
+                    }
+
                     if (is_array($tokens[$i]) === true) {
                         $tokenType = $tokens[$i][0];
                     } else {
@@ -2268,7 +2291,7 @@ protected function tokenize($string)
                     }
 
                     if ($prevNonEmpty === null
-                        && @isset(Tokens::$emptyTokens[$tokenType]) === false
+                        && isset(Tokens::$emptyTokens[$tokenType]) === false
                     ) {
                         // Found the previous non-empty token.
                         if ($tokenType === ':' || $tokenType === ',' || $tokenType === T_ATTRIBUTE_END) {
@@ -2287,8 +2310,8 @@ protected function tokenize($string)
 
                     if ($tokenType === T_FUNCTION
                         || $tokenType === T_FN
-                        || @isset(Tokens::$methodPrefixes[$tokenType]) === true
-                        || @isset(Tokens::$scopeModifiers[$tokenType]) === true
+                        || isset(Tokens::$methodPrefixes[$tokenType]) === true
+                        || isset(Tokens::$scopeModifiers[$tokenType]) === true
                         || $tokenType === T_VAR
                         || $tokenType === T_READONLY
                     ) {
@@ -2311,7 +2334,7 @@ protected function tokenize($string)
                         break;
                     }
 
-                    if (@isset(Tokens::$emptyTokens[$tokenType]) === false) {
+                    if (isset(Tokens::$emptyTokens[$tokenType]) === false) {
                         $lastSeenNonEmpty = $tokenType;
                     }
                 }//end for

tests/Core/Tokenizers/PHP/NullableVsInlineThenParseErrorTest.inc

@@ -0,0 +1,9 @@
+<?php
+
+// This should be the only test in the file.
+// Ref: https://github.com/PHPCSStandards/PHP_CodeSniffer/issues/1216
+
+/* testLiveCoding */
+$ternary = true
+    # This must be a slash or hash comment and the next line must **NOT** have any indentation for the PHP 8.5 deprecation notice to occur.
+? //comment.

tests/Core/Tokenizers/PHP/NullableVsInlineThenParseErrorTest.php

@@ -0,0 +1,40 @@
+<?php
+/**
+ * Tests the retokenization of ? to T_NULLABLE or T_INLINE_THEN.
+ *
+ * @copyright 2025 PHPCSStandards and contributors
+ * @license   https://github.com/PHPCSStandards/PHP_CodeSniffer/blob/master/licence.txt BSD Licence
+ */
+
+namespace PHP_CodeSniffer\Tests\Core\Tokenizers\PHP;
+
+use PHP_CodeSniffer\Tests\Core\Tokenizers\AbstractTokenizerTestCase;
+
+/**
+ * Tests the retokenization of ? to T_NULLABLE or T_INLINE_THEN.
+ *
+ * @covers PHP_CodeSniffer\Tokenizers\PHP::tokenize
+ */
+final class NullableVsInlineThenParseErrorTest extends AbstractTokenizerTestCase
+{
+
+
+    /**
+     * Verify that a "?" as the last functional token in a file (live coding) is tokenized as `T_INLINE_THEN`
+     * as it cannot yet be determined what the token would be once the code is finalized.
+     *
+     * @return void
+     */
+    public function testInlineThenAtEndOfFile()
+    {
+        $tokens     = $this->phpcsFile->getTokens();
+        $target     = $this->getTargetToken('/* testLiveCoding */', [T_NULLABLE, T_INLINE_THEN]);
+        $tokenArray = $tokens[$target];
+
+        $this->assertSame(T_INLINE_THEN, $tokenArray['code'], 'Token tokenized as '.$tokenArray['type'].', not T_INLINE_THEN (code)');
+        $this->assertSame('T_INLINE_THEN', $tokenArray['type'], 'Token tokenized as '.$tokenArray['type'].', not T_INLINE_THEN (type)');
+
+    }//end testInlineThenAtEndOfFile()
+
+
+}//end class

tests/Core/Tokenizers/PHP/NullableVsInlineThenTest.inc

@@ -22,7 +22,11 @@ $closure = function (
     /* testClosureParamTypeNullableInt */
     ?Int $a,
     /* testClosureParamTypeNullableCallable */
-    ?    Callable $b
+    ?    Callable $b,
+    /* testClosureParamTypeNullableStringWithAttributeAndSlashComment */
+    #[AttributeForParam]
+    // This must be a slash or hash comment and the next line must **NOT** have any indentation for the PHP 8.5 deprecation notice (issue PHPCSStandards/PHP_CodeSniffer#1216) to occur.
+?string $c
 /* testClosureReturnTypeNullableInt */
 ) :?INT{};
 

tests/Core/Tokenizers/PHP/NullableVsInlineThenTest.php

@@ -50,16 +50,17 @@ public function testNullable($testMarker)
     public static function dataNullable()
     {
         return [
-            'property declaration, readonly, no visibility'  => ['/* testNullableReadonlyOnly */'],
-            'property declaration, private set'              => ['/* testNullablePrivateSet */'],
-            'property declaration, public and protected set' => ['/* testNullablePublicProtectedSet */'],
-            'property declaration, final, no visibility'     => ['/* testNullableFinalOnly */'],
-            'property declaration, abstract, no visibility'  => ['/* testNullableAbstractOnly */'],
-
-            'closure param type, nullable int'               => ['/* testClosureParamTypeNullableInt */'],
-            'closure param type, nullable callable'          => ['/* testClosureParamTypeNullableCallable */'],
-            'closure return type, nullable int'              => ['/* testClosureReturnTypeNullableInt */'],
-            'function return type, nullable callable'        => ['/* testFunctionReturnTypeNullableCallable */'],
+            'property declaration, readonly, no visibility'                 => ['/* testNullableReadonlyOnly */'],
+            'property declaration, private set'                             => ['/* testNullablePrivateSet */'],
+            'property declaration, public and protected set'                => ['/* testNullablePublicProtectedSet */'],
+            'property declaration, final, no visibility'                    => ['/* testNullableFinalOnly */'],
+            'property declaration, abstract, no visibility'                 => ['/* testNullableAbstractOnly */'],
+
+            'closure param type, nullable int'                              => ['/* testClosureParamTypeNullableInt */'],
+            'closure param type, nullable callable'                         => ['/* testClosureParamTypeNullableCallable */'],
+            'closure param type, nullable string with comment, issue #1216' => ['/* testClosureParamTypeNullableStringWithAttributeAndSlashComment */'],
+            'closure return type, nullable int'                             => ['/* testClosureReturnTypeNullableInt */'],
+            'function return type, nullable callable'                       => ['/* testFunctionReturnTypeNullableCallable */'],
         ];
 
     }//end dataNullable()