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

GenericRuntime.php

@@ -113,7 +113,7 @@ public function getResolver(callable $callable, \ReflectionFunction $reflector =
 
     public function getRunner(?object $application): RunnerInterface
     {
-        $application ??= static function () { return 0; };
+        $application ??= static fn () => 0;
 
         if ($application instanceof RunnerInterface) {
             return $application;

Tests/phpt/dotenv_overload.php

@@ -19,6 +19,4 @@
 
 require __DIR__.'/autoload.php';
 
-return function (Request $request, array $context) {
-    return new Response('OK Request '.$context['SOME_VAR']);
-};
+return fn (Request $request, array $context) => new Response('OK Request '.$context['SOME_VAR']);

Tests/phpt/dotenv_overload_command_debug_exists_0_to_1.php

@@ -20,8 +20,6 @@
 
 require __DIR__.'/autoload.php';
 
-return static function (Command $command, OutputInterface $output, array $context): Command {
-    return $command->setCode(static function () use ($output, $context): void {
-        $output->writeln($context['DEBUG_ENABLED']);
-    });
-};
+return static fn (Command $command, OutputInterface $output, array $context): Command => $command->setCode(static function () use ($output, $context): void {
+    $output->writeln($context['DEBUG_ENABLED']);
+});

Tests/phpt/dotenv_overload_command_debug_exists_1_to_0.php

@@ -20,8 +20,6 @@
 
 require __DIR__.'/autoload.php';
 
-return static function (Command $command, OutputInterface $output, array $context): Command {
-    return $command->setCode(static function () use ($output, $context): void {
-        $output->writeln($context['DEBUG_MODE']);
-    });
-};
+return static fn (Command $command, OutputInterface $output, array $context): Command => $command->setCode(static function () use ($output, $context): void {
+    $output->writeln($context['DEBUG_MODE']);
+});

Tests/phpt/dotenv_overload_command_env_exists.php

@@ -20,8 +20,6 @@
 
 require __DIR__.'/autoload.php';
 
-return static function (Command $command, OutputInterface $output, array $context): Command {
-    return $command->setCode(static function () use ($output, $context): void {
-        $output->writeln($context['ENV_MODE']);
-    });
-};
+return static fn (Command $command, OutputInterface $output, array $context): Command => $command->setCode(static function () use ($output, $context): void {
+    $output->writeln($context['ENV_MODE']);
+});

Tests/phpt/dotenv_overload_command_no_debug.php

@@ -19,8 +19,6 @@
 
 require __DIR__.'/autoload.php';
 
-return static function (Command $command, OutputInterface $output, array $context): Command {
-    return $command->setCode(static function () use ($output, $context): void {
-        $output->writeln($context['DEBUG_ENABLED']);
-    });
-};
+return static fn (Command $command, OutputInterface $output, array $context): Command => $command->setCode(static function () use ($output, $context): void {
+    $output->writeln($context['DEBUG_ENABLED']);
+});

Tests/phpt/kernel.php

@@ -30,6 +30,4 @@ public function handle(Request $request, $type = self::MAIN_REQUEST, $catch = tr
     }
 }
 
-return function (array $context) {
-    return new TestKernel($context['SOME_VAR']);
-};
+return fn (array $context) => new TestKernel($context['SOME_VAR']);

Tests/phpt/request.php

@@ -14,6 +14,4 @@
 
 require __DIR__.'/autoload.php';
 
-return function (Request $request, array $context) {
-    return new Response('OK Request '.$context['SOME_VAR']);
-};
+return fn (Request $request, array $context) => new Response('OK Request '.$context['SOME_VAR']);