Add test

Author: arnaud-lb

Zend/tests/gh18756.phpt

@@ -0,0 +1,11 @@
+--TEST--
+Bug GH-18756: Zend MM may delete the main chunk
+--FILE--
+<?php
+
+zend_test_gh18756();
+
+?>
+==DONE==
+--EXPECT--
+==DONE==

ext/zend_test/test.c

@@ -1516,3 +1516,11 @@ static PHP_FUNCTION(zend_test_create_throwing_resource)
 	zend_resource *res = zend_register_resource(NULL, le_throwing_resource);
 	ZVAL_RES(return_value, res);
 }
+
+PHP_FUNCTION(zend_test_gh18756)
+{
+	zend_mm_heap *heap = zend_mm_startup();
+	zend_mm_gc(heap);
+	zend_mm_gc(heap);
+	zend_mm_shutdown(heap, true, false);
+}

ext/zend_test/test.stub.php

@@ -262,6 +262,8 @@ function zend_test_cast_fread($stream): void {}
     function zend_test_is_zend_ptr(int $addr): bool {}
 
     function zend_test_log_err_debug(string $str): void {}
+
+    function zend_test_gh18756(): void {}
 }
 
 namespace ZendTestNS {