cli: Warn if specified remote branch not found for jj git fetch

* Add new field `unchanged_remote_refs` to GitImportStats.
* Check both `stats.changed_remote_refs` and `stats.unchanged_remote_refs`
  after running `git fetch` and warn if any specified branches is
  not found in either.

Fixes: #4293

CHANGELOG.md

@@ -66,6 +66,9 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixed bugs
 
+ * `jj git fetch -b <remote-git-branch-name>` will now warn if the branch(es)
+   can not be found in any of the remotes.
+
  * Fixed panic when parsing invalid conflict markers of a particular form.
    ([#2611](https://github.com/martinvonz/jj/pull/2611))
 

cli/src/commands/git/fetch.rs

@@ -12,13 +12,18 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use std::collections::HashSet;
+
 use itertools::Itertools;
 use jj_lib::git;
 use jj_lib::git::GitFetchError;
+use jj_lib::git::GitImportStats;
+use jj_lib::git::RefName;
 use jj_lib::repo::Repo;
 use jj_lib::settings::ConfigResultExt as _;
 use jj_lib::settings::UserSettings;
 use jj_lib::str_util::StringPattern;
+use jj_lib::view::View;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::user_error;
@@ -59,14 +64,17 @@ 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 repo = workspace_command.repo();
+    let view = repo.view().clone();
+    let git_repo = get_git_repo(repo.store())?;
     let remotes = if args.all_remotes {
         get_all_remotes(&git_repo)?
     } else if args.remotes.is_empty() {
         get_default_fetch_remotes(ui, command.settings(), &git_repo)?
     } else {
         args.remotes.clone()
     };
+    let mut found_branches: HashSet<&str> = HashSet::from([]);
     let mut tx = workspace_command.start_transaction();
     for remote in &remotes {
         let stats = with_remote_git_callbacks(ui, None, |cb| {
@@ -98,8 +106,24 @@ pub fn cmd_git_fetch(
             GitFetchError::InternalGitError(err) => map_git_error(err),
             _ => user_error(err),
         })?;
+        for pattern in &args.branch {
+            if branch_in_remote(&view, remote, pattern, &stats.import_stats) {
+                found_branches.insert(pattern.as_str());
+                continue;
+            }
+        }
         print_git_import_stats(ui, tx.repo(), &stats.import_stats, true)?;
     }
+    for branch in args
+        .branch
+        .iter()
+        .filter(|b| !found_branches.contains(b.as_str()))
+    {
+        writeln!(
+            ui.warning_default(),
+            "Branch `{branch}` not found on any remote",
+        )?;
+    }
     tx.finish(
         ui,
         format!("fetch from git remote(s) {}", remotes.iter().join(",")),
@@ -140,3 +164,35 @@ fn get_all_remotes(git_repo: &git2::Repository) -> Result<Vec<String>, CommandEr
         .filter_map(|x| x.map(ToOwned::to_owned))
         .collect())
 }
+
+fn matches_remote_branch(
+    pattern: &StringPattern,
+    in_remote: &str,
+    remote_branch: &RefName,
+) -> bool {
+    match remote_branch {
+        RefName::RemoteBranch { branch, remote } => pattern.matches(branch) && remote == in_remote,
+        RefName::LocalBranch(..) | RefName::Tag(..) => false,
+    }
+}
+
+fn branch_in_remote(
+    view: &View,
+    remote: &str,
+    pattern: &StringPattern,
+    stats: &GitImportStats,
+) -> bool {
+    for ref_name in stats.changed_remote_refs.keys() {
+        if matches_remote_branch(pattern, remote, ref_name) {
+            return true;
+        }
+    }
+
+    for (branch, _) in view.remote_bookmarks(remote) {
+        if pattern.matches(branch) {
+            return true;
+        }
+    }
+
+    false
+}

cli/tests/test_git_fetch.rs

@@ -792,6 +792,92 @@ fn test_git_fetch_some_of_many_bookmarks() {
     "###);
 }
 
+#[test]
+fn test_git_fetch_bookmarks_some_missing() {
+    let test_env = TestEnvironment::default();
+    test_env.add_config("git.auto-local-branch = true");
+    test_env.jj_cmd_ok(test_env.env_root(), &["git", "init", "repo"]);
+    let repo_path = test_env.env_root().join("repo");
+    add_git_remote(&test_env, &repo_path, "origin");
+    add_git_remote(&test_env, &repo_path, "rem1");
+    add_git_remote(&test_env, &repo_path, "rem2");
+
+    // single missing bookmark, implicit remotes (@origin)
+    let (_stdout, stderr) =
+        test_env.jj_cmd_ok(&repo_path, &["git", "fetch", "--branch", "noexist"]);
+    insta::assert_snapshot!(stderr, @r###"
+    Warning: Branch `noexist` not found on any remote
+    Nothing changed.
+    "###);
+    insta::assert_snapshot!(get_bookmark_output(&test_env, &repo_path), @"");
+
+    // multiple missing bookmarks, implicit remotes (@origin)
+    let (_stdout, stderr) = test_env.jj_cmd_ok(
+        &repo_path,
+        &[
+            "git", "fetch", "--branch", "noexist1", "--branch", "noexist2",
+        ],
+    );
+    insta::assert_snapshot!(stderr, @r###"
+    Warning: Branch `noexist1` not found on any remote
+    Warning: Branch `noexist2` not found on any remote
+    Nothing changed.
+    "###);
+    insta::assert_snapshot!(get_bookmark_output(&test_env, &repo_path), @"");
+
+    // single existing bookmark, implicit remotes (@origin)
+    let (_stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["git", "fetch", "--branch", "origin"]);
+    insta::assert_snapshot!(stderr, @r###"
+    bookmark: origin@origin [new] tracked
+    "###);
+    insta::assert_snapshot!(get_bookmark_output(&test_env, &repo_path), @r###"
+    origin: oputwtnw ffecd2d6 message
+      @origin: oputwtnw ffecd2d6 message
+    "###);
+
+    // multiple existing bookmark, explicit remotes, each bookmark is only in one
+    // remote.
+    let (_stdout, stderr) = test_env.jj_cmd_ok(
+        &repo_path,
+        &[
+            "git", "fetch", "--branch", "rem1", "--branch", "rem2", "--remote", "rem1", "--remote",
+            "rem2",
+        ],
+    );
+    insta::assert_snapshot!(stderr, @r###"
+    bookmark: rem1@rem1 [new] tracked
+    bookmark: rem2@rem2 [new] tracked
+    "###);
+    insta::assert_snapshot!(get_bookmark_output(&test_env, &repo_path), @r###"
+    origin: oputwtnw ffecd2d6 message
+      @origin: oputwtnw ffecd2d6 message
+    rem1: qxosxrvv 6a211027 message
+      @rem1: qxosxrvv 6a211027 message
+    rem2: yszkquru 2497a8a0 message
+      @rem2: yszkquru 2497a8a0 message
+    "###);
+
+    // multiple bookmarks, one exists, one doesn't
+    let (_stdout, stderr) = test_env.jj_cmd_ok(
+        &repo_path,
+        &[
+            "git", "fetch", "--branch", "rem1", "--branch", "notexist", "--remote", "rem1",
+        ],
+    );
+    insta::assert_snapshot!(stderr, @r###"
+    Warning: Branch `notexist` not found on any remote
+    Nothing changed.
+    "###);
+    insta::assert_snapshot!(get_bookmark_output(&test_env, &repo_path), @r###"
+    origin: oputwtnw ffecd2d6 message
+      @origin: oputwtnw ffecd2d6 message
+    rem1: qxosxrvv 6a211027 message
+      @rem1: qxosxrvv 6a211027 message
+    rem2: yszkquru 2497a8a0 message
+      @rem2: yszkquru 2497a8a0 message
+    "###);
+}
+
 // See `test_undo_restore_commands.rs` for fetch-undo-push and fetch-undo-fetch
 // of the same bookmarks for various kinds of undo.
 #[test]
@@ -1209,6 +1295,7 @@ fn test_git_fetch_removed_parent_bookmark() {
     bookmark: a1@origin     [deleted] untracked
     bookmark: trunk1@origin [deleted] untracked
     Abandoned 1 commits that are no longer reachable.
+    Warning: Branch `master` not found on any remote
     "###);
     insta::assert_snapshot!(get_log_output(&test_env, &target_jj_repo_path), @r###"
     ○  c7d4bdcbc215 descr_for_b b