minor #48793 Leverage arrow function syntax for closure (tigitz)

This PR was merged into the 6.3 branch.

Discussion
----------

Leverage arrow function syntax for closure

| Q             | A
| ------------- | ---
| Branch?       | 6.3
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | Fix #47658 <!-- prefix each issue number with "Fix #", no need to create an issue if none exists, explain below instead -->
| License       | MIT
| Doc PR        | <!-- required for new features -->

Rationale in the RFC [here](https://wiki.php.net/rfc/arrow_functions_v2#introduction)

It's also notable that using arrow function syntax rather than the classic one has been enforced in the past by symfony core member: symfony/symfony#48069 (comment)

So this PR would be consistent.

Commits
-------

f5802d3a2a Leverage arrow function syntax for closure

Author: nicolas-grekas

ExpressionFunction.php

@@ -82,13 +82,9 @@ public static function fromPhp(string $phpFunctionName, string $expressionFuncti
             throw new \InvalidArgumentException(sprintf('An expression function name must be defined when PHP function "%s" is namespaced.', $phpFunctionName));
         }
 
-        $compiler = function (...$args) use ($phpFunctionName) {
-            return sprintf('\%s(%s)', $phpFunctionName, implode(', ', $args));
-        };
+        $compiler = fn (...$args) => sprintf('\%s(%s)', $phpFunctionName, implode(', ', $args));
 
-        $evaluator = function ($p, ...$args) use ($phpFunctionName) {
-            return $phpFunctionName(...$args);
-        };
+        $evaluator = fn ($p, ...$args) => $phpFunctionName(...$args);
 
         return new self($expressionFunctionName ?: end($parts), $compiler, $evaluator);
     }

Tests/Fixtures/TestProvider.php

@@ -19,11 +19,7 @@ class TestProvider implements ExpressionFunctionProviderInterface
     public function getFunctions(): array
     {
         return [
-            new ExpressionFunction('identity', function ($input) {
-                return $input;
-            }, function (array $values, $input) {
-                return $input;
-            }),
+            new ExpressionFunction('identity', fn ($input) => $input, fn (array $values, $input) => $input),
 
             ExpressionFunction::fromPhp('strtoupper'),
 

Tests/Node/FunctionNodeTest.php

@@ -41,12 +41,8 @@ public function getDumpData()
     protected function getCallables()
     {
         return [
-            'compiler' => function ($arg) {
-                return sprintf('foo(%s)', $arg);
-            },
-            'evaluator' => function ($variables, $arg) {
-                return $arg;
-            },
+            'compiler' => fn ($arg) => sprintf('foo(%s)', $arg),
+            'evaluator' => fn ($variables, $arg) => $arg,
         ];
     }
 }