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

* First fetch from remote.
* Then check tx.{base_repo(),repo}.view().remote_bookmarks_matching(<branch>, <remote>).
  This has to happen after the fetch has been done so the tx.repo() is updated.
* Warn if a branch is not found in any of the remotes used in the fetch. Note that the remotes
  used in the fetch can be a subset of the remotes configured for the repo, so the language
  of the warning tries to point that out.

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 specified/configured 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

@@ -21,6 +21,7 @@ use jj_lib::settings::UserSettings;
 use jj_lib::str_util::StringPattern;
 
 use crate::cli_util::CommandHelper;
+use crate::cli_util::WorkspaceCommandTransaction;
 use crate::command_error::user_error;
 use crate::command_error::user_error_with_hint;
 use crate::command_error::CommandError;
@@ -100,6 +101,12 @@ pub fn cmd_git_fetch(
         })?;
         print_git_import_stats(ui, tx.repo(), &stats.import_stats, true)?;
     }
+    warn_if_branches_not_found(
+        ui,
+        &tx,
+        &args.branch,
+        &remotes.iter().map(StringPattern::exact).collect_vec(),
+    )?;
     tx.finish(
         ui,
         format!("fetch from git remote(s) {}", remotes.iter().join(",")),
@@ -140,3 +147,34 @@ fn get_all_remotes(git_repo: &git2::Repository) -> Result<Vec<String>, CommandEr
         .filter_map(|x| x.map(ToOwned::to_owned))
         .collect())
 }
+
+fn warn_if_branches_not_found(
+    ui: &mut Ui,
+    tx: &WorkspaceCommandTransaction,
+    branches: &[StringPattern],
+    remotes: &[StringPattern],
+) -> Result<(), CommandError> {
+    for branch in branches {
+        let matches = remotes.iter().any(|remote| {
+            tx.repo()
+                .view()
+                .remote_bookmarks_matching(branch, remote)
+                .next()
+                .is_some()
+                || tx
+                    .base_repo()
+                    .view()
+                    .remote_bookmarks_matching(branch, remote)
+                    .next()
+                    .is_some()
+        });
+        if !matches {
+            writeln!(
+                ui.warning_default(),
+                "No branch matching `{branch}` found on any specified/configured remote",
+            )?;
+        }
+    }
+
+    Ok(())
+}

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: No branch matching `noexist` found on any specified/configured 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: No branch matching `noexist1` found on any specified/configured remote
+    Warning: No branch matching `noexist2` found on any specified/configured 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: No branch matching `notexist` found on any specified/configured 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: No branch matching `master` found on any specified/configured remote
     "###);
     insta::assert_snapshot!(get_log_output(&test_env, &target_jj_repo_path), @r###"
     ○  c7d4bdcbc215 descr_for_b b