avm1: Fix calling Function() as a function - fixes #1074

core/src/avm1/globals.rs

@@ -438,8 +438,9 @@ pub fn create_globals<'gc>(
         Some(function_proto),
         error_proto,
     );
-    let function = FunctionObject::constructor(
+    let function = FunctionObject::function_and_constructor(
         gc_context,
+        Executable::Native(function::function),
         Executable::Native(function::constructor),
         Some(function_proto),
         function_proto,

core/src/avm1/globals/function.rs

@@ -7,7 +7,7 @@ use crate::avm1::{Object, ScriptObject, TObject, Value};
 use enumset::EnumSet;
 use gc_arena::MutationContext;
 
-/// Implements `Function`
+/// Implements `new Function()`
 pub fn constructor<'gc>(
     _activation: &mut Activation<'_, 'gc, '_>,
     _this: Object<'gc>,
@@ -16,6 +16,20 @@ pub fn constructor<'gc>(
     Ok(Value::Undefined)
 }
 
+/// Implements `Function()`
+pub fn function<'gc>(
+    activation: &mut Activation<'_, 'gc, '_>,
+    _this: Object<'gc>,
+    args: &[Value<'gc>],
+) -> Result<Value<'gc>, Error<'gc>> {
+    if let Some(arg) = args.get(0) {
+        Ok(arg.to_owned())
+    } else {
+        // Calling `Function()` seems to give a prototypeless bare object.
+        Ok(ScriptObject::object(activation.context.gc_context, None).into())
+    }
+}
+
 /// Implements `Function.prototype.call`
 pub fn call<'gc>(
     activation: &mut Activation<'_, 'gc, '_>,