git: get_git_repo -> get_git_backend_repo, distinguish it from curren…

…t worktree

Now that colocated workspaces exist, it is necessary to distinguish the
two kinds of git repository `jj` might open. There's the git backend
(which is either a bare repository or a colocated one) and the worktrees
for all the colocated workspaces. Both of these are a
`gix/git2::Repository`, the difference is just which path you opened. So
you have to distinguish them with names.

This rename mostly serves as an opportunity to review at least some of
the usages of explicit usage of the git backend repo.

cli/src/commands/git/clone.rs

@@ -35,7 +35,7 @@ use crate::commands::git::map_git_error;
 use crate::commands::git::maybe_add_gitignore;
 use crate::config::write_config_value_to_file;
 use crate::config::ConfigNamePathBuf;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::git_util::print_git_import_stats;
 use crate::git_util::with_remote_git_callbacks;
 use crate::ui::Ui;
@@ -204,7 +204,7 @@ fn do_git_clone(
  } else {
  Workspace::init_internal_git(command.settings(), wc_path)?
  };
- let git_repo = get_git_repo(repo.store())?;
+ let git_repo = get_git_backend_repo(repo.store())?;
  writeln!(
  ui.status(),
  r#"Fetching into new repo in "{}""#,

cli/src/commands/git/fetch.rs

@@ -27,7 +27,7 @@ use crate::command_error::user_error_with_hint;
 use crate::command_error::CommandError;
 use crate::commands::git::get_single_remote;
 use crate::commands::git::map_git_error;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::git_util::print_git_import_stats;
 use crate::git_util::with_remote_git_callbacks;
 use crate::ui::Ui;
@@ -60,7 +60,7 @@ pub fn cmd_git_fetch(
  args: &GitFetchArgs,
 ) -> Result<(), CommandError> {
  let mut workspace_command = command.workspace_helper(ui)?;
- let git_repo = get_git_repo(workspace_command.repo().store())?;
+ let git_repo = get_git_backend_repo(workspace_command.repo().store())?;
  let remotes = if args.all_remotes {
  get_all_remotes(&git_repo)?
  } else if args.remotes.is_empty() {

cli/src/commands/git/init.rs

@@ -36,7 +36,7 @@ use crate::command_error::CommandError;
 use crate::commands::git::maybe_add_gitignore;
 use crate::config::write_config_value_to_file;
 use crate::config::ConfigNamePathBuf;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::git_util::is_colocated_git_workspace;
 use crate::git_util::print_failed_git_export;
 use crate::git_util::print_git_import_stats;
@@ -242,7 +242,7 @@ pub fn maybe_set_repository_level_trunk_alias(
  ui: &Ui,
  workspace_command: &WorkspaceCommandHelper,
 ) -> Result<(), CommandError> {
- let git_repo = get_git_repo(workspace_command.repo().store())?;
+ let git_repo = get_git_backend_repo(workspace_command.repo().store())?;
  if let Ok(reference) = git_repo.find_reference("refs/remotes/origin/HEAD") {
  if let Some(reference_name) = reference.symbolic_target() {
  if let Some(RefName::RemoteBranch {

cli/src/commands/git/push.rs

@@ -48,7 +48,7 @@ use crate::command_error::CommandError;
 use crate::commands::git::get_single_remote;
 use crate::commands::git::map_git_error;
 use crate::formatter::Formatter;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::git_util::with_remote_git_callbacks;
 use crate::git_util::GitSidebandProgressMessageWriter;
 use crate::ui::Ui;
@@ -143,7 +143,7 @@ pub fn cmd_git_push(
  args: &GitPushArgs,
 ) -> Result<(), CommandError> {
  let mut workspace_command = command.workspace_helper(ui)?;
- let git_repo = get_git_repo(workspace_command.repo().store())?;
+ let git_repo = get_git_backend_repo(workspace_command.repo().store())?;
 
  let remote = if let Some(name) = &args.remote {
  name.clone()

cli/src/commands/git/remote/add.rs

@@ -17,7 +17,7 @@ use jj_lib::repo::Repo;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::CommandError;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::ui::Ui;
 
 /// Add a Git remote
@@ -36,7 +36,7 @@ pub fn cmd_git_remote_add(
 ) -> Result<(), CommandError> {
  let workspace_command = command.workspace_helper(ui)?;
  let repo = workspace_command.repo();
- let git_repo = get_git_repo(repo.store())?;
+ let git_repo = get_git_backend_repo(repo.store())?;
  git::add_remote(&git_repo, &args.remote, &args.url)?;
  Ok(())
 }

cli/src/commands/git/remote/list.rs

@@ -18,7 +18,7 @@ use jj_lib::repo::Repo;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::CommandError;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::ui::Ui;
 
 /// List Git remotes
@@ -32,7 +32,7 @@ pub fn cmd_git_remote_list(
 ) -> Result<(), CommandError> {
  let workspace_command = command.workspace_helper(ui)?;
  let repo = workspace_command.repo();
- let git_repo = get_git_repo(repo.store())?;
+ let git_repo = get_git_backend_repo(repo.store())?;
  for remote_name in git_repo.remotes()?.iter().flatten() {
  let remote = git_repo.find_remote(remote_name)?;
  writeln!(

cli/src/commands/git/remote/remove.rs

@@ -17,7 +17,7 @@ use jj_lib::repo::Repo;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::CommandError;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::ui::Ui;
 
 /// Remove a Git remote and forget its bookmarks
@@ -34,7 +34,7 @@ pub fn cmd_git_remote_remove(
 ) -> Result<(), CommandError> {
  let mut workspace_command = command.workspace_helper(ui)?;
  let repo = workspace_command.repo();
- let git_repo = get_git_repo(repo.store())?;
+ let git_repo = get_git_backend_repo(repo.store())?;
  let mut tx = workspace_command.start_transaction();
  git::remove_remote(tx.repo_mut(), &git_repo, &args.remote)?;
  if tx.repo().has_changes() {

cli/src/commands/git/remote/rename.rs

@@ -17,7 +17,7 @@ use jj_lib::repo::Repo;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::CommandError;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::ui::Ui;
 
 /// Rename a Git remote
@@ -36,7 +36,7 @@ pub fn cmd_git_remote_rename(
 ) -> Result<(), CommandError> {
  let mut workspace_command = command.workspace_helper(ui)?;
  let repo = workspace_command.repo();
- let git_repo = get_git_repo(repo.store())?;
+ let git_repo = get_git_backend_repo(repo.store())?;
  let mut tx = workspace_command.start_transaction();
  git::rename_remote(tx.repo_mut(), &git_repo, &args.old, &args.new)?;
  if tx.repo().has_changes() {

cli/src/commands/git/remote/set_url.rs

@@ -17,7 +17,7 @@ use jj_lib::repo::Repo;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::CommandError;
-use crate::git_util::get_git_repo;
+use crate::git_util::get_git_backend_repo;
 use crate::ui::Ui;
 
 /// Set the URL of a Git remote
@@ -36,7 +36,7 @@ pub fn cmd_git_remote_set_url(
 ) -> Result<(), CommandError> {
  let workspace_command = command.workspace_helper(ui)?;
  let repo = workspace_command.repo();
- let git_repo = get_git_repo(repo.store())?;
+ let git_repo = get_git_backend_repo(repo.store())?;
  git::set_remote_url(&git_repo, &args.remote, &args.url)?;
  Ok(())
 }

cli/src/git_util.rs

@@ -44,7 +44,16 @@ use crate::formatter::Formatter;
 use crate::progress::Progress;
 use crate::ui::Ui;
 
-pub fn get_git_repo(store: &Store) -> Result<git2::Repository, CommandError> {
+/// This opens a [git2::Repository] for the underlying [GitBackend], assuming
+/// this store is git-backed.
+///
+/// If the JJ repo is colocated with the git repo, then this will often not be
+/// what you want, because its HEAD will always be for the default workspace.
+/// Most JJ commands that access the HEAD need the one for the current
+/// workspace.
+///
+/// However, sometimes you don't care. For example, when you run `jj git fetch`.
+pub fn get_git_backend_repo(store: &Store) -> Result<git2::Repository, CommandError> {
  match store.backend_impl().downcast_ref::<GitBackend>() {
  None => Err(user_error("The repo is not backed by a git repo")),
  Some(git_backend) => Ok(git_backend.open_git_repo()?),