[RFC] Deprecate closure binding issues (php#19510)

alexandre-daubois · web-flow · commit 273d9e290177 · 2025-08-24T00:10:18.000-07:00
https://wiki.php.net/rfc/deprecations_php_8_5
diff --git a/NEWS b/NEWS
@@ -24,6 +24,7 @@ PHP                                                                        NEWS
   . Enacted the follow-up phase of the "Path to Saner Increment/Decrement
     operators" RFC, meaning that incrementing non-numeric strings is now
     deprecated. (Girgias).
+  . Various closure binding issues are now deprecated. (alexandre-daubois)
 
 - Filter:
   . Added support for configuring the URI parser for FILTER_VALIDATE_URL
diff --git a/UPGRADING b/UPGRADING
@@ -360,6 +360,16 @@ PHP 8.5 UPGRADE NOTES
     operators" RFC, meaning that incrementing non-numeric strings is now
     deprecated. Instead the str_increment() function should be used.
     RFC: https://wiki.php.net/rfc/deprecations_php_8_5#enact_follow-up_phase_of_the_path_to_saner_incrementdecrement_operators_rfc
+  . The following closure binding issues, which already emit an E_WARNING, are
+    now deprecated:
+    - Binding an instance to a static closure
+    - Binding methods to objects that are not instances of the class
+      (or subclass) that the method is defined
+    - Unbinding $this from a method
+    - Unbinding $this from a closure that uses `$this`
+    - Binding a closure to the scope of an internal class
+    - Rebinding the scope of a closure created from a function or method
+    RFC: https://wiki.php.net/rfc/deprecations_php_8_5#deprecate_closure_binding_issues
 
 - Curl:
   . The curl_close() function has been deprecated, as CurlHandle objects are
diff --git a/Zend/tests/bug70681.phpt b/Zend/tests/bug70681.phpt
@@ -12,5 +12,5 @@ var_dump($c("foo"));
 
 ?>
 --EXPECTF--
-Warning: Cannot unbind $this of method in %s on line %d
+Warning: Cannot unbind $this of method, this will be an error in PHP 9 in %s on line %d
 int(3)
diff --git a/Zend/tests/closures/bug70630.phpt b/Zend/tests/closures/bug70630.phpt
@@ -7,4 +7,4 @@ $x = (new ReflectionFunction("substr"))->getClosure();
 $x->call(new a);
 ?>
 --EXPECTF--
-Warning: Cannot rebind scope of closure created from function in %s on line %d
+Warning: Cannot rebind scope of closure created from function, this will be an error in PHP 9 in %s on line %d
diff --git a/Zend/tests/closures/bug70685.phpt b/Zend/tests/closures/bug70685.phpt
@@ -15,8 +15,8 @@ var_dump($c);
 
 ?>
 --EXPECTF--
-Warning: Cannot bind method SplDoublyLinkedList::count() to object of class cls in %s on line %d
+Warning: Cannot bind method SplDoublyLinkedList::count() to object of class cls, this will be an error in PHP 9 in %s on line %d
 NULL
 
-Warning: Cannot rebind scope of closure created from method in %s on line %d
+Warning: Cannot rebind scope of closure created from method, this will be an error in PHP 9 in %s on line %d
 NULL
diff --git a/Zend/tests/closures/closure_040.phpt b/Zend/tests/closures/closure_040.phpt
@@ -36,4 +36,4 @@ $cas->bindTo($a, 'A');
 --EXPECTF--
 Closure::bindTo(): Argument #2 ($newScope) must be of type object|string|null, array given
 
-Warning: Cannot bind an instance to a static closure in %s on line %d
+Warning: Cannot bind an instance to a static closure, this will be an error in PHP 9 in %s on line %d
diff --git a/Zend/tests/closures/closure_041.phpt b/Zend/tests/closures/closure_041.phpt
@@ -80,16 +80,16 @@ bound: no
 scoped to A: bool(true)
 bound: no
 
-Warning: Cannot unbind $this of closure using $this in %s on line %d
+Warning: Cannot unbind $this of closure using $this, this will be an error in PHP 9 in %s on line %d
 NULL
 
 After binding, with same-class instance for the bound ones
 
-Warning: Cannot bind an instance to a static closure in %s on line %d
+Warning: Cannot bind an instance to a static closure, this will be an error in PHP 9 in %s on line %d
 scoped to A: bool(false)
 bound: A (should be scoped to dummy class)
 
-Warning: Cannot bind an instance to a static closure in %s on line %d
+Warning: Cannot bind an instance to a static closure, this will be an error in PHP 9 in %s on line %d
 scoped to A: bool(true)
 bound: A
 After binding, with different instance for the bound ones
diff --git a/Zend/tests/closures/closure_043.phpt b/Zend/tests/closures/closure_043.phpt
@@ -56,9 +56,9 @@ bool(false)
 
 After binding, null scope, with instance
 
-Warning: Cannot bind an instance to a static closure in %s on line %d
+Warning: Cannot bind an instance to a static closure, this will be an error in PHP 9 in %s on line %d
 
-Warning: Cannot bind an instance to a static closure in %s on line %d
+Warning: Cannot bind an instance to a static closure, this will be an error in PHP 9 in %s on line %d
 After binding, with scope, no instance
 bool(true)
 bool(false)
@@ -68,7 +68,7 @@ bool(false)
 
 After binding, with scope, with instance
 
-Warning: Cannot bind an instance to a static closure in %s on line %d
+Warning: Cannot bind an instance to a static closure, this will be an error in PHP 9 in %s on line %d
 
-Warning: Cannot bind an instance to a static closure in %s on line %d
+Warning: Cannot bind an instance to a static closure, this will be an error in PHP 9 in %s on line %d
 Done.
diff --git a/Zend/tests/closures/closure_044.phpt b/Zend/tests/closures/closure_044.phpt
@@ -52,7 +52,7 @@ bool(false)
 bool(false)
 
 
-Warning: Cannot unbind $this of closure using $this in %s on line %d
+Warning: Cannot unbind $this of closure using $this, this will be an error in PHP 9 in %s on line %d
 NULL
 
 After binding, null scope, with instance
@@ -67,7 +67,7 @@ bool(true)
 bool(false)
 
 
-Warning: Cannot unbind $this of closure using $this in %s on line %d
+Warning: Cannot unbind $this of closure using $this, this will be an error in PHP 9 in %s on line %d
 NULL
 
 After binding, with scope, with instance
diff --git a/Zend/tests/closures/closure_046.phpt b/Zend/tests/closures/closure_046.phpt
@@ -50,7 +50,7 @@ bool(false)
 bool(false)
 
 
-Warning: Cannot unbind $this of closure using $this in %s on line %d
+Warning: Cannot unbind $this of closure using $this, this will be an error in PHP 9 in %s on line %d
 NULL
 
 After binding, with same-class instance for the bound one
diff --git a/Zend/tests/closures/closure_061.phpt b/Zend/tests/closures/closure_061.phpt
@@ -118,13 +118,13 @@ bindTo(new Cls, null):
 Success!
 
 bindTo(new Cls, Cls::class):
-Cannot rebind scope of closure created from function
+Cannot rebind scope of closure created from function, this will be an error in PHP 9
 
 bindTo(null, Cls::class):
-Cannot rebind scope of closure created from function
+Cannot rebind scope of closure created from function, this will be an error in PHP 9
 
 bindTo(null, stdClass::class):
-Cannot bind closure to scope of internal class stdClass
+Cannot bind closure to scope of internal class stdClass, this will be an error in PHP 9
 
 bindTo(new stdClass, null):
 Success!
@@ -139,13 +139,13 @@ bindTo(new Cls, null):
 Success!
 
 bindTo(new Cls, Cls::class):
-Cannot rebind scope of closure created from function
+Cannot rebind scope of closure created from function, this will be an error in PHP 9
 
 bindTo(null, Cls::class):
-Cannot rebind scope of closure created from function
+Cannot rebind scope of closure created from function, this will be an error in PHP 9
 
 bindTo(null, stdClass::class):
-Cannot bind closure to scope of internal class stdClass
+Cannot bind closure to scope of internal class stdClass, this will be an error in PHP 9
 
 bindTo(new stdClass, null):
 Success!
@@ -157,25 +157,25 @@ bindTo(null, Cls::class):
 Success!
 
 bindTo(new Cls, null):
-Cannot bind an instance to a static closure
+Cannot bind an instance to a static closure, this will be an error in PHP 9
 
 bindTo(new Cls, Cls::class):
-Cannot bind an instance to a static closure
+Cannot bind an instance to a static closure, this will be an error in PHP 9
 
 bindTo(null, null):
-Cannot rebind scope of closure created from method
+Cannot rebind scope of closure created from method, this will be an error in PHP 9
 
 bindTo(null, ClsChild::class):
-Cannot rebind scope of closure created from method
+Cannot rebind scope of closure created from method, this will be an error in PHP 9
 
 bindTo(null, ClsUnrelated::class):
-Cannot rebind scope of closure created from method
+Cannot rebind scope of closure created from method, this will be an error in PHP 9
 
 (new Cls)->method()
 -------------------
 
 bindTo(null, Cls::class):
-Cannot unbind $this of method
+Cannot unbind $this of method, this will be an error in PHP 9
 
 bindTo(new Cls, Cls::class):
 Success!
@@ -184,16 +184,16 @@ bindTo(new ClsChild, Cls::class):
 Success!
 
 bindTo(new ClsUnrelated, Cls::class):
-Cannot bind method Cls::method() to object of class ClsUnrelated
+Cannot bind method Cls::method() to object of class ClsUnrelated, this will be an error in PHP 9
 
 bindTo(new Cls, null):
-Cannot rebind scope of closure created from method
+Cannot rebind scope of closure created from method, this will be an error in PHP 9
 
 bindTo(new Cls, ClsUnrelated::class):
-Cannot rebind scope of closure created from method
+Cannot rebind scope of closure created from method, this will be an error in PHP 9
 
 bindTo(new Cls, ClsChild::class):
-Cannot rebind scope of closure created from method
+Cannot rebind scope of closure created from method, this will be an error in PHP 9
 
 (new SplDoublyLinkedList)->count()
 ----------------------------------
@@ -205,19 +205,19 @@ bindTo(new SplStack, SplDoublyLinkedList::class):
 Success!
 
 bindTo(new ClsUnrelated, SplDoublyLinkedList::class):
-Cannot bind method SplDoublyLinkedList::count() to object of class ClsUnrelated
+Cannot bind method SplDoublyLinkedList::count() to object of class ClsUnrelated, this will be an error in PHP 9
 
 bindTo(null, null):
-Cannot unbind $this of method
+Cannot unbind $this of method, this will be an error in PHP 9
 
 bindTo(null, SplDoublyLinkedList::class):
-Cannot unbind $this of method
+Cannot unbind $this of method, this will be an error in PHP 9
 
 bindTo(new SplDoublyLinkedList, null):
-Cannot rebind scope of closure created from method
+Cannot rebind scope of closure created from method, this will be an error in PHP 9
 
 bindTo(new SplDoublyLinkedList, ClsUnrelated::class):
-Cannot rebind scope of closure created from method
+Cannot rebind scope of closure created from method, this will be an error in PHP 9
 
 (function() {})()
 -----------------
@@ -235,7 +235,7 @@ bindTo(null, Cls::class):
 Success!
 
 bindTo(null, stdClass::class):
-Cannot bind closure to scope of internal class stdClass
+Cannot bind closure to scope of internal class stdClass, this will be an error in PHP 9
 
 bindTo(new stdClass, null):
 Success!
diff --git a/Zend/tests/closures/closure_062.phpt b/Zend/tests/closures/closure_062.phpt
@@ -48,7 +48,7 @@ Test::staticMethod();
 --EXPECTF--
 instance scoped, non-static, $this used
 
-Warning: Cannot unbind $this of closure using $this in %s on line %d
+Warning: Cannot unbind $this of closure using $this, this will be an error in PHP 9 in %s on line %d
 instance scoped, static, $this used
 instance scoped, non-static, $this not used
 static scoped, non-static, $this used
diff --git a/Zend/tests/closures/closure_call.phpt b/Zend/tests/closures/closure_call.phpt
@@ -61,7 +61,7 @@ int(0)
 int(0)
 int(3)
 
-Warning: Cannot bind closure to scope of internal class stdClass in %s line %d
+Warning: Cannot bind closure to scope of internal class stdClass, this will be an error in PHP 9 in %s line %d
 NULL
 int(21)
 int(3)
diff --git a/Zend/tests/closures/closure_from_callable_rebinding.phpt b/Zend/tests/closures/closure_from_callable_rebinding.phpt
@@ -17,4 +17,4 @@ $fn->call(new B);
 
 ?>
 --EXPECTF--
-Warning: Cannot bind method A::method() to object of class B in %s on line %d
+Warning: Cannot bind method A::method() to object of class B, this will be an error in PHP 9 in %s on line %d
diff --git a/Zend/zend_closures.c b/Zend/zend_closures.c
@@ -81,41 +81,41 @@ static bool zend_valid_closure_binding(
 	bool is_fake_closure = (func->common.fn_flags & ZEND_ACC_FAKE_CLOSURE) != 0;
 	if (newthis) {
 		if (func->common.fn_flags & ZEND_ACC_STATIC) {
-			zend_error(E_WARNING, "Cannot bind an instance to a static closure");
+			zend_error(E_WARNING, "Cannot bind an instance to a static closure, this will be an error in PHP 9");
 			return 0;
 		}
 
 		if (is_fake_closure && func->common.scope &&
 				!instanceof_function(Z_OBJCE_P(newthis), func->common.scope)) {
 			/* Binding incompatible $this to an internal method is not supported. */
-			zend_error(E_WARNING, "Cannot bind method %s::%s() to object of class %s",
+			zend_error(E_WARNING, "Cannot bind method %s::%s() to object of class %s, this will be an error in PHP 9",
 					ZSTR_VAL(func->common.scope->name),
 					ZSTR_VAL(func->common.function_name),
 					ZSTR_VAL(Z_OBJCE_P(newthis)->name));
 			return 0;
 		}
 	} else if (is_fake_closure && func->common.scope
 			&& !(func->common.fn_flags & ZEND_ACC_STATIC)) {
-		zend_error(E_WARNING, "Cannot unbind $this of method");
+		zend_error(E_WARNING, "Cannot unbind $this of method, this will be an error in PHP 9");
 		return 0;
 	} else if (!is_fake_closure && !Z_ISUNDEF(closure->this_ptr)
 			&& (func->common.fn_flags & ZEND_ACC_USES_THIS)) {
-		zend_error(E_WARNING, "Cannot unbind $this of closure using $this");
+		zend_error(E_WARNING, "Cannot unbind $this of closure using $this, this will be an error in PHP 9");
 		return 0;
 	}
 
 	if (scope && scope != func->common.scope && scope->type == ZEND_INTERNAL_CLASS) {
 		/* rebinding to internal class is not allowed */
-		zend_error(E_WARNING, "Cannot bind closure to scope of internal class %s",
+		zend_error(E_WARNING, "Cannot bind closure to scope of internal class %s, this will be an error in PHP 9",
 				ZSTR_VAL(scope->name));
 		return 0;
 	}
 
 	if (is_fake_closure && scope != func->common.scope) {
 		if (func->common.scope == NULL) {
-			zend_error(E_WARNING, "Cannot rebind scope of closure created from function");
+			zend_error(E_WARNING, "Cannot rebind scope of closure created from function, this will be an error in PHP 9");
 		} else {
-			zend_error(E_WARNING, "Cannot rebind scope of closure created from method");
+			zend_error(E_WARNING, "Cannot rebind scope of closure created from method, this will be an error in PHP 9");
 		}
 		return 0;
 	}
