Fix GH-11406: segfault with unpacking and magic method closure

The magic method trampoline closure may be variadic. However, the
arg_info for the variadic argument was not set, resulting in a crash
both in reflection and in the VM.

Fix it by creating an arg_info containing a single element in case of
the variadic case. The variadic argument is the last one (and in this
case only one) in the arg_info array.

We make sure the argument info is equivalent to the argument info of
`$closure` of the following code snippet:
```
function foo(...$arguments) {}
$closure = foo(...);
```

Closes GH-11417.

NEWS

@@ -5,6 +5,8 @@ PHP                                                                        NEWS
 - Core:
   . Fix GH-11388 (Allow "final" modifier when importing a method from a trait).
     (nielsdos)
+  . Fixed bug GH-11406 (segfault with unpacking and magic method closure).
+    (nielsdos)
 
 - DOM:
   . Fix #79700 (wrong use of libxml oldNs leads to performance problem).

Zend/tests/trampoline_closure_named_arguments.phpt

@@ -14,19 +14,32 @@ class Test {
 
 $test = new Test;
 
+$array = ["unpacked"];
+
 echo "-- Non-static cases --\n";
 $test->test(1, 2, a: 123);
 $test->test(...)(1, 2);
 $test->test(...)(1, 2, a: 123, b: $test);
 $test->test(...)(a: 123, b: $test);
 $test->test(...)();
+$test->test(...)(...$array);
 
 echo "-- Static cases --\n";
 Test::testStatic(1, 2, a: 123);
 Test::testStatic(...)(1, 2);
 Test::testStatic(...)(1, 2, a: 123, b: $test);
 Test::testStatic(...)(a: 123, b: $test);
 Test::testStatic(...)();
+Test::testStatic(...)(...$array);
+
+echo "-- Reflection tests --\n";
+$reflectionFunction = new ReflectionFunction(Test::fail(...));
+var_dump($reflectionFunction->getParameters());
+$argument = $reflectionFunction->getParameters()[0];
+var_dump($argument->isVariadic());
+$type = $argument->getType();
+var_dump($type);
+var_dump($type->getName());
 
 ?>
 --EXPECT--
@@ -70,6 +83,11 @@ array(2) {
 string(4) "test"
 array(0) {
 }
+string(4) "test"
+array(1) {
+  [0]=>
+  string(8) "unpacked"
+}
 -- Static cases --
 string(10) "testStatic"
 array(3) {
@@ -110,3 +128,20 @@ array(2) {
 string(10) "testStatic"
 array(0) {
 }
+string(10) "testStatic"
+array(1) {
+  [0]=>
+  string(8) "unpacked"
+}
+-- Reflection tests --
+array(1) {
+  [0]=>
+  object(ReflectionParameter)#4 (1) {
+    ["name"]=>
+    string(9) "arguments"
+  }
+}
+bool(true)
+object(ReflectionNamedType)#5 (0) {
+}
+string(5) "mixed"

Zend/zend_closures.c

@@ -833,6 +833,9 @@ ZEND_API void zend_create_fake_closure(zval *res, zend_function *func, zend_clas
 }
 /* }}} */
 
+/* __call and __callStatic name the arguments "$arguments" in the docs. */
+static zend_internal_arg_info trampoline_arg_info[] = {ZEND_ARG_VARIADIC_TYPE_INFO(false, arguments, IS_MIXED, false)};
+
 void zend_closure_from_frame(zval *return_value, zend_execute_data *call) { /* {{{ */
 	zval instance;
 	zend_internal_function trampoline;
@@ -856,6 +859,9 @@ void zend_closure_from_frame(zval *return_value, zend_execute_data *call) { /* {
 		trampoline.handler = zend_closure_call_magic;
 		trampoline.function_name = mptr->common.function_name;
 		trampoline.scope = mptr->common.scope;
+		if (trampoline.fn_flags & ZEND_ACC_VARIADIC) {
+			trampoline.arg_info = trampoline_arg_info;
+		}
 
 		zend_free_trampoline(mptr);
 		mptr = (zend_function *) &trampoline;