feature: NoUselessNullsafeOperatorFixer - Introduction (#6425)

NoUselessNullsafeOperatorFixer - Introduction

doc/list.rst

@@ -1733,6 +1733,13 @@ List of Available Rules
    Part of rule set `@PhpCsFixer <./ruleSets/PhpCsFixer.rst>`_
 
    `Source PhpCsFixer\\Fixer\\ControlStructure\\NoUselessElseFixer <./../src/Fixer/ControlStructure/NoUselessElseFixer.php>`_
+-  `no_useless_nullsafe_operator <./rules/operator/no_useless_nullsafe_operator.rst>`_
+
+   There should not be useless ``null-safe-operators`` ``?->`` used.
+
+   Part of rule sets `@PhpCsFixer <./ruleSets/PhpCsFixer.rst>`_ `@Symfony <./ruleSets/Symfony.rst>`_
+
+   `Source PhpCsFixer\\Fixer\\Operator\\NoUselessNullsafeOperatorFixer <./../src/Fixer/Operator/NoUselessNullsafeOperatorFixer.php>`_
 -  `no_useless_return <./rules/return_notation/no_useless_return.rst>`_
 
    There should not be an empty ``return`` statement at the end of a function.

doc/ruleSets/Symfony.rst

@@ -80,6 +80,7 @@ Rules
 - `no_unneeded_import_alias <./../rules/import/no_unneeded_import_alias.rst>`_
 - `no_unset_cast <./../rules/cast_notation/no_unset_cast.rst>`_
 - `no_unused_imports <./../rules/import/no_unused_imports.rst>`_
+- `no_useless_nullsafe_operator <./../rules/operator/no_useless_nullsafe_operator.rst>`_
 - `no_whitespace_before_comma_in_array <./../rules/array_notation/no_whitespace_before_comma_in_array.rst>`_
 - `normalize_index_brace <./../rules/array_notation/normalize_index_brace.rst>`_
 - `object_operator_without_whitespace <./../rules/operator/object_operator_without_whitespace.rst>`_

doc/rules/index.rst

@@ -520,6 +520,9 @@ Operator
 - `no_space_around_double_colon <./operator/no_space_around_double_colon.rst>`_
 
   There must be no space around double colons (also called Scope Resolution Operator or Paamayim Nekudotayim).
+- `no_useless_nullsafe_operator <./operator/no_useless_nullsafe_operator.rst>`_
+
+  There should not be useless ``null-safe-operators`` ``?->`` used.
 - `not_operator_with_space <./operator/not_operator_with_space.rst>`_
 
   Logical NOT operators (``!``) should have leading and trailing whitespaces.

doc/rules/operator/no_useless_nullsafe_operator.rst

@@ -0,0 +1,35 @@
+=====================================
+Rule ``no_useless_nullsafe_operator``
+=====================================
+
+There should not be useless ``null-safe-operators`` ``?->`` used.
+
+Examples
+--------
+
+Example #1
+~~~~~~~~~~
+
+.. code-block:: diff
+
+   --- Original
+   +++ New
+    <?php
+    class Foo extends Bar
+    {
+        public function test() {
+   -        echo $this?->parentMethod();
+   +        echo $this->parentMethod();
+        }
+    }
+
+Rule sets
+---------
+
+The rule is part of the following rule sets:
+
+@PhpCsFixer
+  Using the `@PhpCsFixer <./../../ruleSets/PhpCsFixer.rst>`_ rule set will enable the ``no_useless_nullsafe_operator`` rule.
+
+@Symfony
+  Using the `@Symfony <./../../ruleSets/Symfony.rst>`_ rule set will enable the ``no_useless_nullsafe_operator`` rule.

src/Fixer/Operator/NoUselessNullsafeOperatorFixer.php

@@ -0,0 +1,82 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *     Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace PhpCsFixer\Fixer\Operator;
+
+use PhpCsFixer\AbstractFixer;
+use PhpCsFixer\FixerDefinition\FixerDefinition;
+use PhpCsFixer\FixerDefinition\FixerDefinitionInterface;
+use PhpCsFixer\FixerDefinition\VersionSpecification;
+use PhpCsFixer\FixerDefinition\VersionSpecificCodeSample;
+use PhpCsFixer\Tokenizer\Token;
+use PhpCsFixer\Tokenizer\Tokens;
+
+final class NoUselessNullsafeOperatorFixer extends AbstractFixer
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function getDefinition(): FixerDefinitionInterface
+    {
+        return new FixerDefinition(
+            'There should not be useless `null-safe-operators` `?->` used.',
+            [
+                new VersionSpecificCodeSample(
+                    '<?php
+class Foo extends Bar
+{
+    public function test() {
+        echo $this?->parentMethod();
+    }
+}
+',
+                    new VersionSpecification(80000)
+                ),
+            ]
+        );
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function isCandidate(Tokens $tokens): bool
+    {
+        return \PHP_VERSION_ID >= 80000 && $tokens->isAllTokenKindsFound([T_VARIABLE, T_NULLSAFE_OBJECT_OPERATOR]);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function applyFix(\SplFileInfo $file, Tokens $tokens): void
+    {
+        for ($index = $tokens->count() - 1; $index >= 0; --$index) {
+            if (!$tokens[$index]->isGivenKind(T_NULLSAFE_OBJECT_OPERATOR)) {
+                continue;
+            }
+
+            $nullsafeObjectOperatorIndex = $index;
+            $index = $tokens->getPrevMeaningfulToken($index);
+
+            if (!$tokens[$index]->isGivenKind(T_VARIABLE)) {
+                continue;
+            }
+
+            if ('$this' !== strtolower($tokens[$index]->getContent())) {
+                continue;
+            }
+
+            $tokens[$nullsafeObjectOperatorIndex] = new Token([T_OBJECT_OPERATOR, '->']);
+        }
+    }
+}

src/RuleSet/Sets/SymfonySet.php

@@ -125,6 +125,7 @@ public function getRules(): array
             'no_unneeded_import_alias' => true,
             'no_unset_cast' => true,
             'no_unused_imports' => true,
+            'no_useless_nullsafe_operator' => true,
             'no_whitespace_before_comma_in_array' => true,
             'normalize_index_brace' => true,
             'object_operator_without_whitespace' => true,

tests/Fixer/Operator/NoUselessNullsafeOperatorFixerTest.php

@@ -0,0 +1,65 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of PHP CS Fixer.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *     Dariusz Rumiński <dariusz.ruminski@gmail.com>
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace PhpCsFixer\Tests\Fixer\Operator;
+
+use PhpCsFixer\Tests\Test\AbstractFixerTestCase;
+
+/**
+ * @internal
+ * @requires PHP 8.0
+ *
+ * @covers \PhpCsFixer\Fixer\Operator\NoUselessNullsafeOperatorFixer
+ */
+final class NoUselessNullsafeOperatorFixerTest extends AbstractFixerTestCase
+{
+    /**
+     * @dataProvider provideFixCases
+     */
+    public function testFix(string $expected, ?string $input = null): void
+    {
+        $this->doTest($expected, $input);
+    }
+
+    public function provideFixCases(): iterable
+    {
+        yield 'simple case + comment' => [
+            '<?php $a = new class extends foo {
+                public function bar() {
+                    $this->g();
+                    // $this?->g();
+                }
+            };',
+            '<?php $a = new class extends foo {
+                public function bar() {
+                    $this?->g();
+                    // $this?->g();
+                }
+            };',
+        ];
+
+        yield 'multiple casing cases + comment + no candidate' => [
+            '<?php $a = new class extends foo {
+                public function bar() {
+                    return $THIS /*1*/ -> g().$THis->g().$this->do()?->o();
+                }
+            };',
+            '<?php $a = new class extends foo {
+                public function bar() {
+                    return $THIS /*1*/ ?-> g().$THis?->g().$this->do()?->o();
+                }
+            };',
+        ];
+    }
+}