php · Girgias · Jun 17, 2021 · Nov 17, 2023 · staabm · Nov 20, 2023
diff --git a/UPGRADING b/UPGRADING
@@ -19,6 +19,16 @@ PHP 8.4 UPGRADE NOTES
 1. Backward Incompatible Changes
 ========================================
 
+- Core:
+  . isset() and empty() now check that the offset for string values is of the
+    correct type i.e. numeric, similarly to array and objects.
+    This means code similar to:
+    $a = 'string';
+    var_dump(isset($a['b']));
+    var_dump(empty($a['b']));
+    will now warn with: "Cannot access offset of type string on string"
+    when previously it silently returned false.
+
 - DOM:
   . New methods and constants were added to some DOM classes. If you inherit
     from these and you happen to have a method or property with the same name,

@@ -5115,7 +5115,8 @@ ZEND_API bool zend_may_throw_ex(const zend_op *opline, const zend_ssa_op *ssa_op
 				return 0;
 			}
 		case ZEND_FETCH_IS:
-			return (t2 & (MAY_BE_ARRAY|MAY_BE_OBJECT));
+			return (t2 & (MAY_BE_ARRAY|MAY_BE_OBJECT))
+				|| (t1 & MAY_BE_STRING && t2 & MAY_BE_STRING);
 		case ZEND_ISSET_ISEMPTY_DIM_OBJ:
 			return (t1 & MAY_BE_OBJECT) || (t2 & (MAY_BE_ARRAY|MAY_BE_OBJECT));
 		case ZEND_FETCH_DIM_IS:

diff --git a/Zend/tests/bug60362.phpt b/Zend/tests/bug60362.phpt
diff --git a/Zend/tests/bug62680.phpt b/Zend/tests/bug62680.phpt
diff --git a/Zend/tests/bug69889.phpt b/Zend/tests/bug69889.phpt
diff --git a/Zend/tests/empty_str_offset.phpt b/Zend/tests/empty_str_offset.phpt