feature: support multibyte strings in substrReplace

refs: #57838

Author: artengin

src/Illuminate/Support/Str.php

@@ -1747,11 +1747,19 @@ public static function substrCount($haystack, $needle, $offset = 0, $length = nu
      */
     public static function substrReplace($string, $replace, $offset = 0, $length = null)
     {
-        if ($length === null) {
-            $length = mb_strlen($string);
+        $encoding = 'UTF-8';
+        $strlen = mb_strlen($string, $encoding);
+
+        if ($offset < 0) {
+            $offset = $offset < -$strlen ? 0 : $strlen + $offset;
         }
 
-        return substr_replace($string, $replace, $offset, $length);
+        $length = is_null($length) ? $strlen - $offset : max($length, 0);
+
+        $start = mb_substr($string, 0, $offset, $encoding);
+        $end = mb_substr($string, $offset + $length, $strlen - ($offset + $length), $encoding);
+
+        return $start . $replace . $end;
     }
 
     /**

tests/Support/SupportStrTest.php

@@ -1262,6 +1262,8 @@ public function testSubstrReplace()
         $this->assertSame('12:00', Str::substrReplace('1200', ':', 2, 0));
         $this->assertSame('The Laravel Framework', Str::substrReplace('The Framework', 'Laravel ', 4, 0));
         $this->assertSame('Laravel – The PHP Framework for Web Artisans', Str::substrReplace('Laravel Framework', '– The PHP Framework for Web Artisans', 8));
+        $this->assertSame('Laravel – PHP 框架的网络专家', Str::substrReplace('Laravel 的网络专家', '– PHP 框架', 8, 0));
+        $this->assertSame('Laravel – PHP Фреймворк для веб-мастеров', Str::substrReplace('Laravel для веб-мастеров', ' – PHP Фреймворк', 7, 0));
     }
 
     public function testTake()