Repeat dynamic property check after __isset for ??

Fixes GH-12695

Author: iluuu1994

Zend/tests/coalesce_is_create_property.phpt

@@ -0,0 +1,22 @@
+--TEST--
+Coalesce IS fetch should repeat dynamic property check after __isset
+--FILE--
+<?php
+#[AllowDynamicProperties]
+class A {
+    public function __isset($prop) {
+        echo __FUNCTION__, "\n";
+        $this->$prop = 123;
+        return true;
+    }
+    public function __get($prop) {
+        throw new Exception('Unreachable');
+    }
+}
+
+$a = new A;
+echo $a->foo ?? 234;
+?>
+--EXPECT--
+__isset
+123

Zend/zend_object_handlers.c

@@ -604,6 +604,36 @@ ZEND_API uint32_t *zend_get_recursion_guard(zend_object *zobj)
 	return &Z_GUARD_P(zv);
 }
 
+static zval *zend_std_read_dynamic_property(zend_object *zobj, zend_string *name, void **cache_slot, uintptr_t property_offset)
+{
+	if (EXPECTED(zobj->properties != NULL)) {
+		if (!IS_UNKNOWN_DYNAMIC_PROPERTY_OFFSET(property_offset)) {
+			uintptr_t idx = ZEND_DECODE_DYN_PROP_OFFSET(property_offset);
+
+			if (EXPECTED(idx < zobj->properties->nNumUsed * sizeof(Bucket))) {
+				Bucket *p = (Bucket*)((char*)zobj->properties->arData + idx);
+
+				if (EXPECTED(p->key == name) ||
+					(EXPECTED(p->h == ZSTR_H(name)) &&
+						EXPECTED(p->key != NULL) &&
+						EXPECTED(zend_string_equal_content(p->key, name)))) {
+					return &p->val;
+				}
+			}
+			CACHE_PTR_EX(cache_slot + 1, (void*)ZEND_DYNAMIC_PROPERTY_OFFSET);
+		}
+		zval *retval = zend_hash_find(zobj->properties, name);
+		if (EXPECTED(retval)) {
+			if (cache_slot) {
+				uintptr_t idx = (char*)retval - (char*)zobj->properties->arData;
+				CACHE_PTR_EX(cache_slot + 1, (void*)ZEND_ENCODE_DYN_PROP_OFFSET(idx));
+			}
+			return retval;
+		}
+	}
+	return NULL;
+}
+
 ZEND_API zval *zend_std_read_property(zend_object *zobj, zend_string *name, int type, void **cache_slot, zval *rv) /* {{{ */
 {
 	zval *retval;
@@ -655,31 +685,9 @@ ZEND_API zval *zend_std_read_property(zend_object *zobj, zend_string *name, int
 			goto uninit_error;
 		}
 	} else if (EXPECTED(IS_DYNAMIC_PROPERTY_OFFSET(property_offset))) {
-		if (EXPECTED(zobj->properties != NULL)) {
-			if (!IS_UNKNOWN_DYNAMIC_PROPERTY_OFFSET(property_offset)) {
-				uintptr_t idx = ZEND_DECODE_DYN_PROP_OFFSET(property_offset);
-
-				if (EXPECTED(idx < zobj->properties->nNumUsed * sizeof(Bucket))) {
-					Bucket *p = (Bucket*)((char*)zobj->properties->arData + idx);
-
-					if (EXPECTED(p->key == name) ||
-				        (EXPECTED(p->h == ZSTR_H(name)) &&
-				         EXPECTED(p->key != NULL) &&
-				         EXPECTED(zend_string_equal_content(p->key, name)))) {
-						retval = &p->val;
-						goto exit;
-					}
-				}
-				CACHE_PTR_EX(cache_slot + 1, (void*)ZEND_DYNAMIC_PROPERTY_OFFSET);
-			}
-			retval = zend_hash_find(zobj->properties, name);
-			if (EXPECTED(retval)) {
-				if (cache_slot) {
-					uintptr_t idx = (char*)retval - (char*)zobj->properties->arData;
-					CACHE_PTR_EX(cache_slot + 1, (void*)ZEND_ENCODE_DYN_PROP_OFFSET(idx));
-				}
-				goto exit;
-			}
+		retval = zend_std_read_dynamic_property(zobj, name, cache_slot, property_offset);
+		if (retval) {
+			goto exit;
 		}
 	} else if (UNEXPECTED(EG(exception))) {
 		retval = &EG(uninitialized_zval);
@@ -710,6 +718,13 @@ ZEND_API zval *zend_std_read_property(zend_object *zobj, zend_string *name, int
 			}
 
 			zval_ptr_dtor(&tmp_result);
+
+			retval = zend_std_read_dynamic_property(zobj, name, cache_slot, property_offset);
+			if (retval) {
+				OBJ_RELEASE(zobj);
+				goto exit;
+			}
+
 			if (zobj->ce->__get && !((*guard) & IN_GET)) {
 				goto call_getter;
 			}