Fix GH-11310: __debugInfo() does nothing on classes extending DateTime

* Implemented `__debugInfo` for `DateTime` and `DateTimeImmutable`.
* Modified the `get_properties_for` handlers of `DateTime` and
  `DateTimeImmutable` to invoke `__debugInfo`.

Author: paulfedorow

ext/date/php_date.c

@@ -1959,6 +1959,13 @@ static HashTable *date_object_get_properties_for(zend_object *object, zend_prop_
 
 	switch (purpose) {
 		case ZEND_PROP_PURPOSE_DEBUG:
+			assert(object->ce->__debugInfo != NULL);
+			int is_temp = 0;
+			HashTable *ht = zend_std_get_debug_info(object, &is_temp);
+			if (ht && !is_temp) {
+				GC_TRY_ADDREF(ht);
+			}
+			return ht;
 		case ZEND_PROP_PURPOSE_SERIALIZE:
 		case ZEND_PROP_PURPOSE_VAR_EXPORT:
 		case ZEND_PROP_PURPOSE_JSON:
@@ -2845,6 +2852,44 @@ PHP_METHOD(DateTimeImmutable, __serialize)
 }
 /* }}} */
 
+/* {{{ */
+PHP_METHOD(DateTime, __debugInfo)
+{
+	zval             *object = ZEND_THIS;
+	php_date_obj     *dateobj;
+	HashTable        *myht;
+
+	ZEND_PARSE_PARAMETERS_NONE();
+
+	dateobj = Z_PHPDATE_P(object);
+	DATE_CHECK_INITIALIZED(dateobj->time, Z_OBJCE_P(object));
+
+	array_init(return_value);
+	myht = Z_ARRVAL_P(return_value);
+	add_common_properties(myht, &dateobj->std);
+	date_object_to_hash(dateobj, myht);
+}
+/* }}} */
+
+/* {{{ */
+PHP_METHOD(DateTimeImmutable, __debugInfo)
+{
+	zval             *object = ZEND_THIS;
+	php_date_obj     *dateobj;
+	HashTable        *myht;
+
+	ZEND_PARSE_PARAMETERS_NONE();
+
+	dateobj = Z_PHPDATE_P(object);
+	DATE_CHECK_INITIALIZED(dateobj->time, Z_OBJCE_P(object));
+
+	array_init(return_value);
+	myht = Z_ARRVAL_P(return_value);
+	add_common_properties(myht, &dateobj->std);
+	date_object_to_hash(dateobj, myht);
+}
+/* }}} */
+
 static bool date_time_is_internal_property(zend_string *name)
 {
 	if (

ext/date/php_date.stub.php

@@ -344,6 +344,9 @@ public function __serialize(): array {}
 
     public function __unserialize(array $data): void {}
 
+    /** @tentative-return-type */
+    public function __debugInfo(): array {}
+
     /** @tentative-return-type */
     public function __wakeup(): void {}
 
@@ -454,6 +457,9 @@ public function __serialize(): array {}
 
     public function __unserialize(array $data): void {}
 
+    /** @tentative-return-type */
+    public function __debugInfo(): array {}
+
     /** @tentative-return-type */
     public function __wakeup(): void {}
 

ext/date/php_date_arginfo.h

@@ -0,0 +1,59 @@
+--TEST--
+Bug GH-11310: __debugInfo() does nothing on classes extending DateTime
+--INI--
+date.timezone=UTC
+--FILE--
+<?php
+
+class MyDateTime extends DateTime {
+    public function __debugInfo(): array {
+        return ['child' => '42', 'parent' => count(parent::__debugInfo())];
+    }
+}
+
+class MyDateTimeImmutable extends DateTimeImmutable {
+    public function __debugInfo(): array {
+        return ['child' => '42', 'parent' => count(parent::__debugInfo())];
+    }
+}
+
+class MyDateTimeZone extends DateTimeZone {
+    public function __debugInfo(): array {
+        return ['child' => '42', 'parent' => count(parent::__debugInfo())];
+    }
+}
+
+var_dump(new DateTime('2023-10-26 21:23:05'));
+var_dump(new DateTimeImmutable('2023-10-26 21:23:05'));
+var_dump(new MyDateTime('2023-10-26 21:23:05'));
+var_dump(new MyDateTimeImmutable('2023-10-26 21:23:05'));
+?>
+--EXPECT--
+object(DateTime)#1 (3) {
+  ["date"]=>
+  string(26) "2023-10-26 21:23:05.000000"
+  ["timezone_type"]=>
+  int(3)
+  ["timezone"]=>
+  string(3) "UTC"
+}
+object(DateTimeImmutable)#1 (3) {
+  ["date"]=>
+  string(26) "2023-10-26 21:23:05.000000"
+  ["timezone_type"]=>
+  int(3)
+  ["timezone"]=>
+  string(3) "UTC"
+}
+object(MyDateTime)#1 (2) {
+  ["child"]=>
+  string(2) "42"
+  ["parent"]=>
+  int(3)
+}
+object(MyDateTimeImmutable)#1 (2) {
+  ["child"]=>
+  string(2) "42"
+  ["parent"]=>
+  int(3)
+}