Implement GH-13609: Dump wrapped object in WeakReference class (#13621)

I chose "object" as that's also the argument name in WeakReference::create.

NEWS

@@ -15,6 +15,7 @@ PHP                                                                        NEWS
   . Fixed zend call stack size for macOs/arm64. (David Carlier)
   . Added support for Zend Max Execution Timers on FreeBSD. (Kévin Dunglas)
   . Ensure fiber stack is not backed by THP. (crrodriguez)
+  . Implement GH-13609 (Dump wrapped object in WeakReference class). (nielsdos)
 
 - Curl:
   . Deprecated the CURLOPT_BINARYTRANSFER constant. (divinity76)

UPGRADING

@@ -164,6 +164,8 @@ PHP 8.4 UPGRADE NOTES
   . Added request_parse_body() function that allows parsing RFC1867 (multipart)
     requests in non-POST HTTP requests.
     RFC: https://wiki.php.net/rfc/rfc1867-non-post
+  . Getting the debug info for WeakReference will now also output the object
+    it references, or null if the reference is no longer valid.
 
 - Curl:
   . curl_version() returns an additional feature_list value, which is an

Zend/tests/weakrefs/weakrefs_001.phpt

@@ -26,9 +26,15 @@ object(stdClass)#1 (0) refcount(2){
 }
 object(stdClass)#1 (0) refcount(2){
 }
-object(WeakReference)#2 (0) {
+object(WeakReference)#2 (1) {
+  ["object"]=>
+  object(stdClass)#1 (0) {
+  }
 }
-object(WeakReference)#2 (0) {
+object(WeakReference)#2 (1) {
+  ["object"]=>
+  object(stdClass)#1 (0) {
+  }
 }
 object(stdClass)#1 (0) refcount(2){
 }
@@ -36,4 +42,3 @@ object(stdClass)#1 (0) refcount(2){
 }
 NULL
 NULL
-

Zend/tests/weakrefs/weakrefs_debug_dump.phpt

@@ -0,0 +1,26 @@
+--TEST--
+Weakrefs debug dump
+--FILE--
+<?php
+
+$s = new stdClass;
+$s->hello = 'world';
+
+$weak = WeakReference::create($s);
+var_dump($weak);
+unset($s);
+var_dump($weak);
+
+?>
+--EXPECT--
+object(WeakReference)#2 (1) {
+  ["object"]=>
+  object(stdClass)#1 (1) {
+    ["hello"]=>
+    string(5) "world"
+  }
+}
+object(WeakReference)#2 (1) {
+  ["object"]=>
+  NULL
+}

Zend/zend_weakrefs.c

@@ -271,6 +271,25 @@ static void zend_weakref_free(zend_object *zo) {
 	zend_object_std_dtor(&wr->std);
 }
 
+static HashTable *zend_weakref_get_debug_info(zend_object *object, int *is_temp)
+{
+	*is_temp = 1;
+
+	HashTable *ht = zend_new_array(1);
+
+	zend_object *referent = zend_weakref_from(object)->referent;
+	zval value;
+	if (referent) {
+		ZVAL_OBJ_COPY(&value, referent);
+	} else {
+		ZVAL_NULL(&value);
+	}
+
+	zend_hash_update(ht, ZSTR_KNOWN(ZEND_STR_OBJECT), &value);
+
+	return ht;
+}
+
 ZEND_COLD ZEND_METHOD(WeakReference, __construct)
 {
 	zend_throw_error(NULL, "Direct instantiation of WeakReference is not allowed, use WeakReference::create instead");
@@ -749,6 +768,7 @@ void zend_register_weakref_ce(void) /* {{{ */
 	zend_weakref_handlers.offset = XtOffsetOf(zend_weakref, std);
 
 	zend_weakref_handlers.free_obj = zend_weakref_free;
+	zend_weakref_handlers.get_debug_info = zend_weakref_get_debug_info;
 	zend_weakref_handlers.clone_obj = NULL;
 
 	zend_ce_weakmap = register_class_WeakMap(zend_ce_arrayaccess, zend_ce_countable, zend_ce_aggregate);