avm2: Implement `rest` parameters in function calls.

core/src/avm2/activation.rs

@@ -184,11 +184,8 @@ impl<'a, 'gc, 'gc_context> Activation<'a, 'gc, 'gc_context> {
             .body()
             .ok_or_else(|| "Cannot execute non-native method without body".into());
         let num_locals = body?.num_locals;
-        let arg_register = if method.method().needs_arguments_object {
-            1
-        } else {
-            0
-        };
+        let has_rest_or_args = method.method().needs_arguments_object || method.method().needs_rest;
+        let arg_register = if has_rest_or_args { 1 } else { 0 };
         let num_declared_arguments = method.method().params.len() as u32;
         let local_registers = GcCell::allocate(
             context.gc_context,
@@ -219,8 +216,19 @@ impl<'a, 'gc, 'gc_context> Activation<'a, 'gc, 'gc_context> {
             context,
         };
 
-        if method.method().needs_arguments_object {
-            let args_array = ArrayStorage::from_args(arguments);
+        if has_rest_or_args {
+            let args_array = if method.method().needs_arguments_object {
+                ArrayStorage::from_args(arguments)
+            } else if method.method().needs_rest {
+                if let Some(rest_args) = arguments.get(num_declared_arguments as usize..) {
+                    ArrayStorage::from_args(rest_args)
+                } else {
+                    ArrayStorage::new(0)
+                }
+            } else {
+                unreachable!();
+            };
+
             let mut args_object = ArrayObject::from_array(
                 args_array,
                 activation
@@ -233,12 +241,14 @@ impl<'a, 'gc, 'gc_context> Activation<'a, 'gc, 'gc_context> {
                 activation.context.gc_context,
             );
 
+            if method.method().needs_arguments_object {
                 args_object.set_property(
                     args_object,
                     &QName::new(Namespace::public_namespace(), "callee"),
                     callee.into(),
                     &mut activation,
                 )?;
+            }
 
             *local_registers
                 .write(activation.context.gc_context)

core/tests/regression_tests.rs

@@ -455,6 +455,7 @@ swf_tests! {
     (as3_event_isdefaultprevented, "avm2/event_isdefaultprevented", 1),
     (as3_function_call_via_apply, "avm2/function_call_via_apply", 1),
     (as3_function_call_arguments, "avm2/function_call_arguments", 1),
+    (as3_function_call_rest, "avm2/function_call_rest", 1),
 }
 
 // TODO: These tests have some inaccuracies currently, so we use approx_eq to test that numeric values are close enough.

core/tests/swfs/avm2/function_call_rest/Test.as

@@ -0,0 +1,34 @@
+package {
+	public class Test {}
+}
+
+function testrest(arg0, arg1, ...rest) {
+	trace(arg0);
+	trace(arg1);
+	
+	trace("///(contents of rest...)");
+	trace(rest.length);
+	
+	for (var i = 0; i < rest.length; i += 1) {
+		trace(rest[i]);
+	}
+}
+
+function restprops(...rest) {
+	trace("///Array.prototype.test = \"test\";");
+	Array.prototype.test = "test";
+	
+	trace("///rest.test");
+	trace(rest.test);
+}
+
+trace("///testrest(\"arg1\");");
+testrest("arg1");
+
+trace("///testrest(\"arg1\", \"arg2\", \"arg3\");");
+testrest("arg1", "arg2", "arg3");
+
+trace("///testrest(\"arg1\", \"arg2\", \"arg3\", \"arg4\", \"arg5\");");
+testrest("arg1", "arg2", "arg3", "arg4", "arg5");
+
+restprops();

core/tests/swfs/avm2/function_call_rest/output.txt

@@ -0,0 +1,22 @@
+///testrest("arg1");
+arg1
+undefined
+///(contents of rest...)
+0
+///testrest("arg1", "arg2", "arg3");
+arg1
+arg2
+///(contents of rest...)
+1
+arg3
+///testrest("arg1", "arg2", "arg3", "arg4", "arg5");
+arg1
+arg2
+///(contents of rest...)
+3
+arg3
+arg4
+arg5
+///Array.prototype.test = "test";
+///rest.test
+test