Use static closure if possible

ptscs/ruleset.xml

@@ -193,6 +193,7 @@
     <rule ref="SlevomatCodingStandard.Variables.UnusedVariable" />
     <rule ref="SlevomatCodingStandard.Functions.UnusedInheritedVariablePassedToClosure" />
     <rule ref="SlevomatCodingStandard.Functions.DisallowEmptyFunction" />
+    <rule ref="SlevomatCodingStandard.Functions.StaticClosure" />
     <rule ref="SlevomatCodingStandard.Commenting.DisallowOneLinePropertyDocComment" />
     <rule ref="SlevomatCodingStandard.Commenting.EmptyComment" />
 

tests/Sniffs/Slevomat/Functions/StaticClosureTest.php

@@ -0,0 +1,23 @@
+<?php declare(strict_types=1);
+
+namespace Ptscs\Tests\Sniffs\Slevomat\Functions;
+
+use Iterator;
+use Ptscs\Tests\SniffTestCase;
+use Ptscs\Tests\Utils\ErrorData;
+
+final class StaticClosureTest extends SniffTestCase
+{
+    protected function setUp(): void
+    {
+        parent::setUp();
+        $this->appendExclude('Squiz.Classes.ClassFileName.NoMatch');
+    }
+
+    public static function provideTestData(): Iterator
+    {
+        yield[
+          [new ErrorData(9, 'SlevomatCodingStandard.Functions.StaticClosure.ClosureNotStatic')],
+        ];
+    }
+}

tests/Sniffs/Slevomat/Functions/_data/StaticClosure.php.fixed

@@ -0,0 +1,13 @@
+<?php declare(strict_types=1);
+
+namespace App;
+
+final class Foobar
+{
+    public function callback()
+    {
+        return static function () {
+            return 'Test';
+        };
+    }
+}

tests/Sniffs/Slevomat/Functions/_data/StaticClosure.php.inc

@@ -0,0 +1,13 @@
+<?php declare(strict_types=1);
+
+namespace App;
+
+final class Foobar
+{
+    public function callback()
+    {
+        return function () {
+            return 'Test';
+        };
+    }
+}

tests/Sniffs/Slevomat/_data/UnusedInheritedVariablePassedToClosure.php.fixed

@@ -6,7 +6,7 @@ final class Foobar
 {
     public function __invoke(): callable
     {
-        return function () {
+        return static function () {
         };
     }
 }

tests/Sniffs/Slevomat/_data/UnusedInheritedVariablePassedToClosure.php.inc

@@ -6,7 +6,7 @@ final class Foobar
 {
     public function __invoke(): callable
     {
-        return function () use ($name) {
+        return static function () use ($name) {
         };
     }
 }

tests/Sniffs/Unsolved/_data/ScopeIndent.php.fixed

@@ -1,6 +1,6 @@
 <?php declare(strict_types=1);
 
-$this->callback(function () {
+$this->callback(static function () {
     if (true) {
     }
 

tests/Sniffs/Unsolved/_data/ScopeIndent.php.inc

@@ -1,6 +1,6 @@
 <?php declare(strict_types=1);
 
-$this->callback(function () {
+$this->callback(static function () {
     if (true) {
     }