core: set zend_pass_function as default constructor

This is to make the semantics of when a class cannot be instiantiated obvious rather than needed to remember to call the get_constructor() handler.

For this we create a new NonInstantiableClass attribute that can be set to mark classes which shouldn't be instantiable with a message and set the constructor pointer to NULL

Author: Girgias

Zend/Optimizer/escape_analysis.c

@@ -167,7 +167,7 @@ static bool is_allocation_def(zend_op_array *op_array, zend_ssa *ssa, int def, i
 				 && !ce->create_object
 				 && ce->default_object_handlers->get_constructor == zend_std_get_constructor
 				 && ce->default_object_handlers->dtor_obj == zend_objects_destroy_object
-				 && !ce->constructor
+				 && (!ce->constructor || zend_is_pass_function(ce->constructor))
 				 && !ce->destructor
 				 && !ce->__get
 				 && !ce->__set
@@ -236,7 +236,7 @@ static bool is_local_def(zend_op_array *op_array, zend_ssa *ssa, int def, int va
 				 && !ce->create_object
 				 && ce->default_object_handlers->get_constructor == zend_std_get_constructor
 				 && ce->default_object_handlers->dtor_obj == zend_objects_destroy_object
-				 && !ce->constructor
+				 && (!ce->constructor || zend_is_pass_function(ce->constructor))
 				 && !ce->destructor
 				 && !ce->__get
 				 && !ce->__set

Zend/Optimizer/zend_inference.c

@@ -3393,7 +3393,7 @@ static zend_always_inline zend_result _zend_update_type_info(
 			}
 			/* New objects without constructors cannot escape. */
 			if (ce
-			 && !ce->constructor
+			 && (!ce->constructor || zend_is_pass_function(ce->constructor))
 			 && !ce->create_object
 			 && ce->default_object_handlers->get_constructor == zend_std_get_constructor) {
 				tmp &= ~MAY_BE_RCN;

Zend/tests/enum/no-new-through-reflection.phpt

@@ -7,10 +7,10 @@ enum Foo {}
 
 try {
     (new \ReflectionClass(Foo::class))->newInstanceWithoutConstructor();
-} catch (Error $e) {
-    echo $e->getMessage() . "\n";
+} catch (Throwable $e) {
+    echo $e::class, ': ', $e->getMessage() . "\n";
 }
 
 ?>
 --EXPECT--
-Cannot instantiate enum Foo
+ReflectionException: Class Foo cannot be instantiated manually

Zend/tests/traits/bug60173.phpt

@@ -9,7 +9,7 @@ $rc = new ReflectionClass('foo');
 $rc->newInstance();
 ?>
 --EXPECTF--
-Fatal error: Uncaught Error: Cannot instantiate trait foo in %s:%d
+Fatal error: Uncaught ReflectionException: Class foo cannot be instantiated manually in %s:%d
 Stack trace:
 #0 %s(%d): ReflectionClass->newInstance()
 #1 {main}

Zend/zend_API.c

@@ -3510,6 +3510,11 @@ static zend_class_entry *do_register_internal_class(const zend_class_entry *orig
 	if (class_entry->info.internal.builtin_functions) {
 		zend_register_functions(class_entry, class_entry->info.internal.builtin_functions, &class_entry->function_table, EG(current_module)->type);
 	}
+	
+	/* Assign the pass function as a default constructor */
+	if (class_entry->constructor == NULL) {
+		class_entry->constructor = (zend_function *) &zend_pass_function;
+	}
 
 	lowercase_name = zend_string_tolower_ex(orig_class_entry->name, EG(current_module)->type == MODULE_PERSISTENT);
 	lowercase_name = zend_new_interned_string(lowercase_name);

Zend/zend_attributes.c

@@ -32,6 +32,7 @@ ZEND_API zend_class_entry *zend_ce_override;
 ZEND_API zend_class_entry *zend_ce_deprecated;
 ZEND_API zend_class_entry *zend_ce_nodiscard;
 ZEND_API zend_class_entry *zend_ce_delayed_target_validation;
+ZEND_API zend_class_entry *zend_ce_non_instantiable_class;
 
 static zend_object_handlers attributes_object_handlers_sensitive_parameter_value;
 
@@ -264,6 +265,24 @@ ZEND_METHOD(NoDiscard, __construct)
 	}
 }
 
+ZEND_METHOD(NonInstantiableClass, __construct)
+{
+	zend_string *message = NULL;
+	zval value;
+
+	ZEND_PARSE_PARAMETERS_START(1, 1)
+		Z_PARAM_STR(message)
+	ZEND_PARSE_PARAMETERS_END();
+
+	ZVAL_STR(&value, message);
+	zend_update_property_ex(zend_ce_non_instantiable_class, Z_OBJ_P(ZEND_THIS), ZSTR_KNOWN(ZEND_STR_MESSAGE), &value);
+
+	/* The assignment might fail due to 'readonly'. */
+	if (UNEXPECTED(EG(exception))) {
+		RETURN_THROWS();
+	}
+}
+
 static zend_attribute *get_attribute(const HashTable *attributes, const zend_string *lcname, uint32_t offset)
 {
 	if (attributes) {
@@ -605,6 +624,9 @@ void zend_register_attribute_ce(void)
 
 	zend_ce_delayed_target_validation = register_class_DelayedTargetValidation();
 	attr = zend_mark_internal_attribute(zend_ce_delayed_target_validation);
+
+	zend_ce_non_instantiable_class = register_class_NonInstantiableClass();
+	attr = zend_mark_internal_attribute(zend_ce_delayed_target_validation);
 }
 
 void zend_attributes_shutdown(void)

Zend/zend_attributes.stub.php

@@ -103,3 +103,13 @@ public function __construct(?string $message = null) {}
  */
 #[Attribute(Attribute::TARGET_ALL)]
 final class DelayedTargetValidation {}
+
+/**
+ * @strict-properties
+ */
+#[Attribute(Attribute::TARGET_CLASS)]
+final class NonInstantiableClass {
+    public readonly string $message;
+
+    public function __construct(string $message) {}
+}

Zend/zend_attributes_arginfo.h

@@ -20,6 +20,7 @@
 #include "zend.h"
 #include "zend_API.h"
 #include "zend_closures.h"
+#include "zend_attributes.h"
 #include "zend_exceptions.h"
 #include "zend_interfaces.h"
 #include "zend_objects.h"
@@ -448,13 +449,6 @@ ZEND_METHOD(Closure, getCurrent)
 	RETURN_OBJ_COPY(obj);
 }
 
-static ZEND_COLD zend_function *zend_closure_get_constructor(zend_object *object) /* {{{ */
-{
-	zend_throw_error(NULL, "Instantiation of class Closure is not allowed");
-	return NULL;
-}
-/* }}} */
-
 /* int return due to Object Handler API */
 static int zend_closure_compare(zval *o1, zval *o2) /* {{{ */
 {
@@ -736,7 +730,6 @@ void zend_register_closure_ce(void) /* {{{ */
 
 	memcpy(&closure_handlers, &std_object_handlers, sizeof(zend_object_handlers));
 	closure_handlers.free_obj = zend_closure_free_storage;
-	closure_handlers.get_constructor = zend_closure_get_constructor;
 	closure_handlers.get_method = zend_closure_get_method;
 	closure_handlers.compare = zend_closure_compare;
 	closure_handlers.clone_obj = zend_closure_clone;

Zend/zend_closures.c

@@ -6,6 +6,7 @@
  * @strict-properties
  * @not-serializable
  */
+#[\NonInstantiableClass("Instantiation of class Closure is not allowed")]
 final class Closure
 {
     private function __construct() {}