ext/gmp: Make GMP class final

NEWS

@@ -21,6 +21,9 @@ PHP                                                                        NEWS
   . /dev/poll events.mechanism for Solaris/Illumos setting had been retired.
     (David Carlier)
 
+- GMP:
+  . The GMP class is now final and cannot be extended anymore.
+
 - Intl:
   . Added SpoofChecker::setAllowedChars to set unicode chars ranges.
     (David Carlier)

UPGRADING

@@ -48,6 +48,10 @@ PHP 8.4 UPGRADE NOTES
     object. This is no longer possible, and cloning a DOMXPath object now throws
     an error.
 
+- GMP:
+  . The GMP class is now final and cannot be extended anymore.
+    RFC: https://wiki.php.net/rfc/gmp-final
+
 - Intl:
   . resourcebundle_get(), ResourceBundle::get(), and accessing offsets on a
     ResourceBundle object now throw:

ext/gmp/gmp.stub.php

@@ -57,7 +57,7 @@
  */
 const GMP_NATIVE_ENDIAN = UNKNOWN;
 
-class GMP
+final class GMP
 {
     public function __construct(int|string $num = 0, int $base = 0) {}
 

ext/gmp/tests/final.phpt

@@ -0,0 +1,12 @@
+--TEST--
+Cannot extend GMP class
+--EXTENSIONS--
+gmp
+--FILE--
+<?php
+
+class T extends GMP {}
+
+?>
+--EXPECTF--
+Fatal error: Class T cannot extend final class GMP in %s on line %d