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

AbstractUnicodeString.php

@@ -360,9 +360,7 @@ public function title(bool $allWords = false): static
 
         $limit = $allWords ? -1 : 1;
 
-        $str->string = preg_replace_callback('/\b./u', static function (array $m): string {
-            return mb_convert_case($m[0], \MB_CASE_TITLE, 'UTF-8');
-        }, $str->string, $limit);
+        $str->string = preg_replace_callback('/\b./u', static fn (array $m): string => mb_convert_case($m[0], \MB_CASE_TITLE, 'UTF-8'), $str->string, $limit);
 
         return $str;
     }

Resources/WcswidthDataGenerator.php

@@ -104,9 +104,7 @@ private function format(array $rawData): array
             return [hexdec($start), hexdec($end)];
         }, $rawData);
 
-        usort($data, static function (array $a, array $b): int {
-            return $a[0] - $b[0];
-        });
+        usort($data, static fn (array $a, array $b): int => $a[0] - $b[0]);
 
         return $data;
     }

Slugger/AsciiSlugger.php

@@ -121,9 +121,7 @@ public function slug(string $string, string $separator = '-', string $locale = n
             // If the symbols map is passed as a closure, there is no need to fallback to the parent locale
             // as the closure can just provide substitutions for all locales of interest.
             $symbolsMap = $this->symbolsMap;
-            array_unshift($transliterator, static function ($s) use ($symbolsMap, $locale) {
-                return $symbolsMap($s, $locale);
-            });
+            array_unshift($transliterator, static fn ($s) => $symbolsMap($s, $locale));
         }
 
         $unicodeString = (new UnicodeString($string))->ascii($transliterator);

Tests/AbstractAsciiTestCase.php

@@ -993,9 +993,7 @@ public static function provideReplaceMatches()
             ['April,15,2003', 'April 15, 2003', '/(\w+) (\d+), (\d+)/i', '${1},$2,$3'],
             ['5/27/1999', '1999-5-27', '/(19|20)(\d{2})-(\d{1,2})-(\d{1,2})/', '\3/\4/\1\2'],
             ['Copyright 2000', 'Copyright 1999', '([0-9]+)', '2000'],
-            ['hello world! this is a test', 'HELLO WORLD! THIS is a test', '/\b([A-Z]+)\b/', function ($word) {
-                return strtolower($word[1]);
-            }],
+            ['hello world! this is a test', 'HELLO WORLD! THIS is a test', '/\b([A-Z]+)\b/', fn ($word) => strtolower($word[1])],
             ['COPYRIGHT 1999', 'Copyright 1999', '/[a-z]/', function ($matches) {
                 foreach ($matches as $match) {
                     return strtoupper($match);

Tests/AbstractUnicodeTestCase.php

@@ -44,9 +44,7 @@ public function testAscii()
 
     public function testAsciiClosureRule()
     {
-        $rule = function ($c) {
-            return str_replace('ö', 'OE', $c);
-        };
+        $rule = fn ($c) => str_replace('ö', 'OE', $c);
 
         $s = static::createFromString('Dieser Wert sollte größer oder gleich');
         $this->assertSame('Dieser Wert sollte grOEsser oder gleich', (string) $s->ascii([$rule]));

Tests/LazyStringTest.php

@@ -29,6 +29,21 @@ public function testLazyString()
         $this->assertSame(1, $count);
     }
 
+    /**
+     * @runInSeparateProcess
+     */
+    public function testReturnTypeError()
+    {
+        ErrorHandler::register();
+
+        $s = LazyString::fromCallable(fn () => []);
+
+        $this->expectException(\TypeError::class);
+        $this->expectExceptionMessage('Return value of '.__NAMESPACE__.'\{closure}() passed to '.LazyString::class.'::fromCallable() must be of the type string, array returned.');
+
+        (string) $s;
+    }
+
     public function testLazyCallable()
     {
         $count = 0;
@@ -55,21 +70,6 @@ public function __invoke()
         $this->assertSame(1, $count);
     }
 
-    /**
-     * @runInSeparateProcess
-     */
-    public function testReturnTypeError()
-    {
-        ErrorHandler::register();
-
-        $s = LazyString::fromCallable(function () { return []; });
-
-        $this->expectException(\TypeError::class);
-        $this->expectExceptionMessage('Return value of '.__NAMESPACE__.'\{closure}() passed to '.LazyString::class.'::fromCallable() must be of the type string, array returned.');
-
-        (string) $s;
-    }
-
     public function testFromStringable()
     {
         $this->assertInstanceOf(LazyString::class, LazyString::fromStringable('abc'));