cli: add a debug command for generic working copy info

We have two other kinds of working copies at Google and it's sometimes
useful to get the basic information about operation id and tree id for
them, for exampel for debugging stale workspaces. This patch adds a
command for that.

We could instead have made the old `jj debug working-copy` command
work for all kinds of working copies (like the new command) and only
have extra information for the standard local-disk implementation. I
don't feel strongly either way and could do it other other way instead
if people prefer that.

cli/src/commands/debug/local_working_copy.rs

@@ -23,6 +23,8 @@ use crate::command_error::CommandError;
 use crate::ui::Ui;
 
 /// Show information about the local working copy state
+///
+/// This command only works with a standard local-disk working copy.
 #[derive(clap::Args, Clone, Debug)]
 pub struct LocalWorkingCopyArgs {}
 

cli/src/commands/debug/mod.rs

@@ -22,6 +22,7 @@ pub mod snapshot;
 pub mod template;
 pub mod tree;
 pub mod watchman;
+pub mod working_copy;
 
 use std::any::Any;
 use std::fmt::Debug;
@@ -39,6 +40,7 @@ use self::snapshot::{cmd_debug_snapshot, SnapshotArgs};
 use self::template::{cmd_debug_template, TemplateArgs};
 use self::tree::{cmd_debug_tree, TreeArgs};
 use self::watchman::{cmd_debug_watchman, WatchmanCommand};
+use self::working_copy::{cmd_debug_working_copy, WorkingCopyArgs};
 use crate::cli_util::CommandHelper;
 use crate::command_error::{user_error, CommandError};
 use crate::ui::Ui;
@@ -59,6 +61,7 @@ pub enum DebugCommand {
     Tree(TreeArgs),
     #[command(subcommand)]
     Watchman(WatchmanCommand),
+    WorkingCopy(WorkingCopyArgs),
 }
 
 pub fn cmd_debug(
@@ -77,6 +80,7 @@ pub fn cmd_debug(
         DebugCommand::Template(args) => cmd_debug_template(ui, command, args),
         DebugCommand::Tree(args) => cmd_debug_tree(ui, command, args),
         DebugCommand::Watchman(args) => cmd_debug_watchman(ui, command, args),
+        DebugCommand::WorkingCopy(args) => cmd_debug_working_copy(ui, command, args),
     }
 }
 

cli/src/commands/debug/working_copy.rs

@@ -0,0 +1,37 @@
+// Copyright 2023 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 std::fmt::Debug;
+use std::io::Write as _;
+
+use crate::cli_util::CommandHelper;
+use crate::command_error::CommandError;
+use crate::ui::Ui;
+
+/// Show information about the working copy state
+#[derive(clap::Args, Clone, Debug)]
+pub struct WorkingCopyArgs {}
+
+pub fn cmd_debug_working_copy(
+    ui: &mut Ui,
+    command: &CommandHelper,
+    _args: &WorkingCopyArgs,
+) -> Result<(), CommandError> {
+    let workspace_command = command.workspace_helper_no_snapshot(ui)?;
+    let wc = workspace_command.working_copy();
+    writeln!(ui.stdout(), "Type: {:?}", wc.name())?;
+    writeln!(ui.stdout(), "Current operation: {:?}", wc.operation_id())?;
+    writeln!(ui.stdout(), "Current tree: {:?}", wc.tree_id()?)?;
+    Ok(())
+}