Properly check visibility/staticness and allow abstract private

Author: nikic

Zend/tests/traits/abstract_method_1.phpt

@@ -4,13 +4,13 @@ Abstract method from trait enforced in class
 <?php
 
 trait T {
-    abstract function neededByTheTrait(int $a, string $b);
+    abstract public function neededByTheTrait(int $a, string $b);
 }
 
 class C {
     use T;
 
-    function neededByTheTrait(array $a, object $b) {}
+    public function neededByTheTrait(array $a, object $b) {}
 }
 
 ?>

Zend/tests/traits/abstract_method_2.phpt

@@ -13,7 +13,7 @@ trait T2 {
 class C {
     use T1, T2;
 
-    function test(): int {}
+    public function test(): int {}
 }
 
 ?>

Zend/tests/traits/abstract_method_3.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Private abstract method from trait enforced in class
+--FILE--
+<?php
+
+trait T {
+    abstract private function neededByTheTrait(int $a, string $b);
+}
+
+class C {
+    use T;
+
+    private function neededByTheTrait(array $a, object $b) {}
+}
+
+?>
+--EXPECTF--
+Fatal error: Declaration of C::neededByTheTrait(array $a, object $b) must be compatible with T::neededByTheTrait(int $a, string $b) in %s on line %d

Zend/tests/traits/abstract_method_4.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Visibility enforcement on abstract trait methods
+--FILE--
+<?php
+
+trait T {
+    abstract public function method(int $a, string $b);
+}
+
+class C {
+    use T;
+
+    private function method(int $a, string $b) {}
+}
+
+?>
+--EXPECTF--
+Fatal error: Access level to C::method() must be public (as in class T) in %s on line %d

Zend/tests/traits/abstract_method_5.phpt

@@ -0,0 +1,18 @@
+--TEST--
+Staticness enforcement on abstract trait methods
+--FILE--
+<?php
+
+trait T {
+    abstract static public function method(int $a, string $b);
+}
+
+class C {
+    use T;
+
+    public function method(int $a, string $b) {}
+}
+
+?>
+--EXPECTF--
+Fatal error: Cannot make static method T::method() non static in class C in %s on line %d

Zend/zend_compile.c

@@ -6023,7 +6023,7 @@ void zend_begin_method_decl(zend_op_array *op_array, zend_string *name, zend_boo
 	}
 
 	if (op_array->fn_flags & ZEND_ACC_ABSTRACT) {
-		if (op_array->fn_flags & ZEND_ACC_PRIVATE) {
+		if ((op_array->fn_flags & ZEND_ACC_PRIVATE) && !(ce->ce_flags & ZEND_ACC_TRAIT)) {
 			zend_error_noreturn(E_COMPILE_ERROR, "%s function %s::%s() cannot be declared private",
 				in_interface ? "Interface" : "Abstract", ZSTR_VAL(ce->name), ZSTR_VAL(name));
 		}

Zend/zend_inheritance.c

@@ -508,8 +508,10 @@ static inheritance_status zend_do_perform_implementation_check(
 		&& ((proto->common.scope->ce_flags & ZEND_ACC_INTERFACE) == 0
 			&& (proto->common.fn_flags & ZEND_ACC_ABSTRACT) == 0)));
 
-	/* If the prototype method is private do not enforce a signature */
-	ZEND_ASSERT(!(proto->common.fn_flags & ZEND_ACC_PRIVATE));
+	/* If the prototype method is private and not abstract, we do not enforce a signature.
+	 * private abstract methods can only occur in traits. */
+	ZEND_ASSERT(!(proto->common.fn_flags & ZEND_ACC_PRIVATE)
+			|| (proto->common.fn_flags & ZEND_ACC_ABSTRACT));
 
 	/* The number of required arguments cannot increase. */
 	if (proto->common.required_num_args < fe->common.required_num_args) {
@@ -824,7 +826,7 @@ static zend_always_inline inheritance_status do_inheritance_check_on_method_ex(z
 		child->common.fn_flags |= ZEND_ACC_CHANGED;
 	}
 
-	if (parent_flags & ZEND_ACC_PRIVATE) {
+	if ((parent_flags & ZEND_ACC_PRIVATE) && !(parent_flags & ZEND_ACC_ABSTRACT)) {
 		return INHERITANCE_SUCCESS;
 	}
 
@@ -1562,7 +1564,8 @@ static void zend_add_trait_method(zend_class_entry *ce, const char *name, zend_s
 
 		/* Abstract method signatures from the trait must be satisfied. */
 		if (fn->common.fn_flags & ZEND_ACC_ABSTRACT) {
-			perform_delayable_implementation_check(ce, existing_fn, fn);
+			do_inheritance_check_on_method(existing_fn, fn, ce, NULL);
+			fn->common.prototype = NULL;
 			return;
 		}