From 6434b5c5b638544420897c8aac3d7129339314ef Mon Sep 17 00:00:00 2001
From: Daniel Scherzer <daniel.e.scherzer@gmail.com>
Date: Mon, 24 Feb 2025 10:36:01 -0800
Subject: [PATCH] Fix GH-17916: Final abstract properties should error

---
 NEWS                                              |  2 ++
 .../tests/property_hooks/abstract_prop_final.phpt | 14 ++++++++++++++
 Zend/zend_compile.c                               | 15 +++++++++++----
 3 files changed, 27 insertions(+), 4 deletions(-)
 create mode 100644 Zend/tests/property_hooks/abstract_prop_final.phpt

diff --git a/NEWS b/NEWS
index 69c6e954b66b5..74a03c5c3a53f 100644
--- a/NEWS
+++ b/NEWS
@@ -17,6 +17,8 @@ PHP                                                                        NEWS
     `__callStatic` is allowed). (timwolla)
   . Fixed bug GH-17713 (ReflectionProperty::getRawValue() and related methods
     may call hooks of overridden properties). (Arnaud)
+  . Fixed bug GH-17916 (Final abstract properties should error).
+    (DanielEScherzer)
 
 - DOM:
   . Fixed bug GH-17609 (Typo in error message: Dom\NO_DEFAULT_NS instead of
diff --git a/Zend/tests/property_hooks/abstract_prop_final.phpt b/Zend/tests/property_hooks/abstract_prop_final.phpt
new file mode 100644
index 0000000000000..17f2282507f1f
--- /dev/null
+++ b/Zend/tests/property_hooks/abstract_prop_final.phpt
@@ -0,0 +1,14 @@
+--TEST--
+GH-17916: Abstract property cannot be marked as final
+--FILE--
+<?php
+
+abstract class Foo {
+    final abstract public string $bar {
+        get;
+    }
+}
+
+?>
+--EXPECTF--
+Fatal error: Cannot use the final modifier on an abstract property in %s on line %d
diff --git a/Zend/zend_compile.c b/Zend/zend_compile.c
index 667257f730658..ef75b45ad0528 100644
--- a/Zend/zend_compile.c
+++ b/Zend/zend_compile.c
@@ -1036,10 +1036,17 @@ uint32_t zend_add_member_modifier(uint32_t flags, uint32_t new_flag, zend_modifi
 			"Multiple readonly modifiers are not allowed", 0);
 		return 0;
 	}
-	if (target == ZEND_MODIFIER_TARGET_METHOD && (new_flags & ZEND_ACC_ABSTRACT) && (new_flags & ZEND_ACC_FINAL)) {
-		zend_throw_exception(zend_ce_compile_error,
-			"Cannot use the final modifier on an abstract method", 0);
-		return 0;
+	if ((new_flags & ZEND_ACC_ABSTRACT) && (new_flags & ZEND_ACC_FINAL)) {
+		if (target == ZEND_MODIFIER_TARGET_METHOD) {
+			zend_throw_exception(zend_ce_compile_error,
+				"Cannot use the final modifier on an abstract method", 0);
+			return 0;
+		}
+		if (target == ZEND_MODIFIER_TARGET_PROPERTY) {
+			zend_throw_exception(zend_ce_compile_error,
+				"Cannot use the final modifier on an abstract property", 0);
+			return 0;
+		}
 	}
 	if (target == ZEND_MODIFIER_TARGET_PROPERTY || target == ZEND_MODIFIER_TARGET_CPP) {
 		if ((flags & ZEND_ACC_PPP_SET_MASK) && (new_flag & ZEND_ACC_PPP_SET_MASK)) {