Fix GH-25108: Skip uninitialized hooked properties in json_encode()

NEWS

@@ -115,6 +115,8 @@ PHP                                                                        NEWS
     INT_MIN. (Marc Bennewitz)
 
 - JSON:
+  . Fixed bug GH-25108 (json_encode() serializes uninitialized properties
+    with setter hooks as null). (JoaoMarcos44)
   . Fixed json_encode() leaving the recursion guard set on objects with hooked
     properties after running out of memory while escaping a property name.
     (adapik)

ext/json/json_encoder.c

@@ -295,6 +295,10 @@ static zend_result php_json_encode_array(smart_str *buf, zval *val, int options,
 							zval_ptr_dtor(&tmp);
 							return FAILURE;
 						}
+						if (UNEXPECTED(data == &EG(uninitialized_zval))) {
+							zval_ptr_dtor(&tmp);
+							continue;
+						}
 					}
 
 					if (need_comma) {

ext/json/tests/gh25108.phpt

@@ -0,0 +1,66 @@
+--TEST--
+GH-25108 (json_encode() skips uninitialized hooked properties)
+--FILE--
+<?php
+
+class UninitializedProperties
+{
+    public int $plain;
+    public int $hooked {
+        set => $value;
+    }
+    public ?int $hookedNullable {
+        set => $value;
+    }
+}
+
+class MixedProperties
+{
+    public int $firstMissing {
+        set => $value;
+    }
+    public string $first = 'first';
+    public ?string $middleMissing {
+        set => $value;
+    }
+    public ?string $getterNull {
+        get => null;
+    }
+    public ?string $backedNull = null {
+        set => $value;
+    }
+    public int $backedValue = 42 {
+        set => $value;
+    }
+    public string $last = 'last';
+    public int $lastMissing {
+        set => $value;
+    }
+    public ?string $virtualSetOnly {
+        set {}
+    }
+}
+
+$empty = new UninitializedProperties();
+echo json_encode($empty), "\n";
+
+$empty->hooked = 7;
+$empty->hookedNullable = null;
+echo json_encode($empty), "\n";
+
+$mixed = new MixedProperties();
+echo json_encode($mixed), "\n";
+echo json_encode($mixed, JSON_PRETTY_PRINT), "\n";
+
+?>
+--EXPECT--
+{}
+{"hooked":7,"hookedNullable":null}
+{"first":"first","getterNull":null,"backedNull":null,"backedValue":42,"last":"last"}
+{
+    "first": "first",
+    "getterNull": null,
+    "backedNull": null,
+    "backedValue": 42,
+    "last": "last"
+}