Function derive_and_copy_attributes

crates/vm/src/exception_group.rs:444–482

(
        orig: &Py<PyBaseException>,
        excs: Vec<PyObjectRef>,
        vm: &VirtualMachine,
    )

    }

    fn derive_and_copy_attributes(
        orig: &Py<PyBaseException>,
        excs: Vec<PyObjectRef>,
        vm: &VirtualMachine,
    ) -> PyResult<PyObjectRef> {
        // Call derive method to create new group
        let excs_seq = vm.ctx.new_list(excs);
        let new_group = vm.call_method(orig.as_object(), "derive", (excs_seq,))?;

        // Verify derive returned a BaseExceptionGroup
        if !is_base_exception_group(&new_group, vm) {
            return Err(vm.new_type_error("derive must return an instance of BaseExceptionGroup"));
        }

        // Copy traceback
        if let Some(tb) = orig.__traceback__() {
            new_group.set_attr("__traceback__", tb, vm)?;
        }

        // Copy context
        if let Some(ctx) = orig.__context__() {
            new_group.set_attr("__context__", ctx, vm)?;
        }

        // Copy cause
        if let Some(cause) = orig.__cause__() {
            new_group.set_attr("__cause__", cause, vm)?;
        }

        // Copy notes (if present) - make a copy of the list
        if let Ok(notes) = orig.as_object().get_attr("__notes__", vm)
            && let Some(notes_list) = notes.downcast_ref::<PyList>()
        {
            let notes_copy = vm.ctx.new_list(notes_list.borrow_vec().to_vec());
            new_group.set_attr("__notes__", notes_copy, vm)?;
        }

        Ok(new_group)
    }
}