[PHP 8.0] Add preg_last_error_msg function

Author: Nicolas Oelgart

Php80.php

@@ -13,6 +13,7 @@
 
 /**
  * @author Ion Bazan <[email protected]>
+ * @author Nico Oelgart <[email protected]>
  *
  * @internal
  */
@@ -26,6 +27,28 @@ public static function fdiv($dividend, $divisor)
         return (float) @($dividend / $divisor);
     }
 
+    public static function pregLastErrorMsg()
+    {
+        switch (preg_last_error()) {
+            case PREG_INTERNAL_ERROR:
+                return 'Internal error';
+            case PREG_BAD_UTF8_ERROR:
+                return 'Malformed UTF-8 characters, possibly incorrectly encoded';
+            case PREG_BAD_UTF8_OFFSET_ERROR:
+                return 'The offset did not correspond to the beginning of a valid UTF-8 code point';
+            case PREG_BACKTRACK_LIMIT_ERROR:
+                return 'Backtrack limit exhausted';
+            case PREG_RECURSION_LIMIT_ERROR:
+                return 'Recursion limit exhausted';
+            case PREG_JIT_STACKLIMIT_ERROR:
+                return 'JIT stack limit exhausted';
+            case PREG_NO_ERROR:
+                return 'No error';
+            default:
+                return 'Unknown error';
+        }
+    }
+
     private static function floatArg($value, $caller, $pos)
     {
         if (\is_float($value)) {

README.md

@@ -6,6 +6,7 @@ This component provides functions added to PHP 8.0 core:
 - [`fdiv`](https://php.net/fdiv) (only for PHP 7.0+)
 - `ValueError` class
 - `FILTER_VALIDATE_BOOL` constant
+- [`preg_last_error_msg`](https://php.net/preg_last_error_msg)
 
 More information can be found in the
 [main Polyfill README](https://github.com/symfony/polyfill/blob/master/README.md).

bootstrap.php

@@ -16,6 +16,10 @@
         function fdiv($dividend, $divisor) { return p\Php80::fdiv($dividend, $divisor); }
     }
 
+    if (!function_exists('preg_last_error_msg')) {
+        function preg_last_error_msg() { return p\Php80::pregLastErrorMsg(); }
+    }
+
     if (!defined('FILTER_VALIDATE_BOOL') && defined('FILTER_VALIDATE_BOOLEAN')) {
         define('FILTER_VALIDATE_BOOL', FILTER_VALIDATE_BOOLEAN);
     }