avm2: Throw proper error when setting name of timeline objects

core/src/avm2/error.rs

@@ -210,6 +210,17 @@ pub fn verify_error<'gc>(
     error_constructor(activation, class, message, code)
 }
 
+#[inline(never)]
+#[cold]
+pub fn illegal_operation_error<'gc>(
+    activation: &mut Activation<'_, 'gc>,
+    message: &str,
+    code: u32,
+) -> Result<Value<'gc>, Error<'gc>> {
+    let class = activation.avm2().classes().illegaloperationerror;
+    error_constructor(activation, class, message, code)
+}
+
 #[inline(never)]
 #[cold]
 pub fn io_error<'gc>(

core/src/avm2/globals/flash/display/display_object.rs

@@ -1,7 +1,7 @@
 //! `flash.display.DisplayObject` builtin/prototype
 
 use crate::avm2::activation::Activation;
-use crate::avm2::error::{argument_error, make_error_2008};
+use crate::avm2::error::{argument_error, illegal_operation_error, make_error_2008};
 use crate::avm2::filters::FilterAvm2Ext;
 use crate::avm2::object::{Object, TObject};
 use crate::avm2::parameters::ParametersExt;
@@ -490,10 +490,11 @@ pub fn set_name<'gc>(
         let new_name = args.get_string(activation, 0)?;
 
         if dobj.instantiated_by_timeline() {
-            return Err(format!(
-                "Display object {new_name} was placed by the timeline and cannot have it's name changed.",
-            )
-            .into());
+            return Err(Error::AvmError(illegal_operation_error(
+                activation,
+                "Error #2078: The name property of a Timeline-placed object cannot be modified.",
+                2078,
+            )?));
         }
 
         dobj.set_name(activation.context.gc_context, new_name);

tests/tests/swfs/avm1/movieclip_name_from_timeline/output.txt

@@ -0,0 +1,14 @@
+// circle.
+_level0.circle
+
+// circle._name
+circle
+
+// circle._name = "square"
+
+// circle
+undefined
+
+// square
+_level0.square
+

tests/tests/swfs/avm1/movieclip_name_from_timeline/test.toml

@@ -0,0 +1 @@
+num_frames = 1

tests/tests/swfs/avm2/displayobject_name_from_timeline/Test.as

@@ -0,0 +1,62 @@
+package  {
+	
+	import flash.display.MovieClip;
+	import flash.utils.describeType;
+	import flash.display.Sprite;
+	
+	
+	public class Test extends MovieClip {
+		
+		
+		public function Test() {
+			trace("// circle.");
+			trace(circle);
+			trace("");
+			
+			trace("// circle.name");
+			trace(circle.name);
+			trace("");
+			
+			trace("// circle.name = \"square\"");
+			try {
+				circle.name = "square";
+			} catch (e) {
+				trace(e);
+			}
+			trace("");
+			
+			trace("// circle");
+			trace(circle);
+			trace("");
+			
+			trace("// circle.name");
+			trace(circle.name);
+			trace("");
+			
+			trace("// removeChild(circle)");
+			removeChild(circle);
+			trace("");
+			
+			trace("// circle.name = \"square\"");
+			try {
+				circle.name = "square";
+			} catch (e) {
+				trace(e);
+			}
+			trace("");
+			
+			trace("// addChild(circle)");
+			addChild(circle);
+			trace("");
+			
+			trace("// circle.name = \"square\"");
+			try {
+				circle.name = "square";
+			} catch (e) {
+				trace(e);
+			}
+			trace("");
+		}
+	}
+	
+}

tests/tests/swfs/avm2/displayobject_name_from_timeline/output.txt

@@ -0,0 +1,25 @@
+// circle.
+[object MovieClip]
+
+// circle.name
+circle
+
+// circle.name = "square"
+Error: Error #2078: The name property of a Timeline-placed object cannot be modified.
+
+// circle
+[object MovieClip]
+
+// circle.name
+circle
+
+// removeChild(circle)
+
+// circle.name = "square"
+Error: Error #2078: The name property of a Timeline-placed object cannot be modified.
+
+// addChild(circle)
+
+// circle.name = "square"
+Error: Error #2078: The name property of a Timeline-placed object cannot be modified.
+

tests/tests/swfs/avm2/displayobject_name_from_timeline/test.toml

@@ -0,0 +1 @@
+num_frames = 1