// Copyright 2020 The Jujutsu Authors//// Licensed under the Apache License, Version 2.0 (the "License");// you may not use this file except in compliance with the License.// You may obtain a copy of the License at//// https://www.apache.org/licenses/LICENSE-2.0//// Unless required by applicable law or agreed to in writing, software// distributed under the License is distributed on an "AS IS" BASIS,// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.// See the License for the specific language governing permissions and// limitations under the License. use jj_lib::object_id::ObjectId;use tracing::instrument; use crate::cli_util::{CommandHelper, RevisionArg};use crate::command_error::CommandError;use crate::description_util::join_message_paragraphs;use crate::ui::Ui; /// Create a new, empty change and edit it in the working copy////// For more information, see/// https://github.com/martinvonz/jj/blob/main/docs/working-copy.md.#[derive(clap::Args, Clone, Debug)]pub(crate) struct CheckoutArgs {    /// The revision to update to    revision: RevisionArg,    /// Ignored (but lets you pass `-r` for consistency with other commands)    #[arg(short = 'r', hide = true)]    unused_revision: bool,    /// The change description to use    #[arg(long = "message", short, value_name = "MESSAGE")]    message_paragraphs: Vec<String>,} #[instrument(skip_all)]pub(crate) fn cmd_checkout(    ui: &mut Ui,    command: &CommandHelper,    args: &CheckoutArgs,) -> Result<(), CommandError> {    writeln!(        ui.warning(),        "warning: `jj checkout` is deprecated; use `jj new` instead, which is equivalent"    )?;    writeln!(        ui.warning(),        "warning: `jj checkout` will be removed in a future version, and this will be a hard error"    )?;    let mut workspace_command = command.workspace_helper(ui)?;    let target = workspace_command.resolve_single_rev(&args.revision)?;    let mut tx = workspace_command.start_transaction();    let commit_builder = tx        .mut_repo()        .new_commit(            command.settings(),            vec![target.id().clone()],            target.tree_id().clone(),        )        .set_description(join_message_paragraphs(&args.message_paragraphs));    let new_commit = commit_builder.write()?;    tx.edit(&new_commit).unwrap();    tx.finish(ui, format!("check out commit {}", target.id().hex()))?;    Ok(())}