cli: git push: show hint when there are bookmarks pending deletion

This comes from a personal experience where the following sequence of
events happened:

1. `jj git push -c @-`
2. Oops, that was the wrong one, so I'll `jj bookmark delete` and `jj
   git push`
3. Hm... why didn't that do anything? Oh, right, `--deleted`

As described in the diff, this hint only fires when `jj git push` is
used with no arguments, as any user that passes `--all`, `--tracked`, or
`--revisions` (targeting a deleted bookmark) will already get an error
instructing them to use `--deleted`.

Author: winterqt

CHANGELOG.md

@@ -42,6 +42,9 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   template, to the commit description. Use cases include DCO Sign Off and
   Gerrit Change Id.
 
+* `jj git push` now shows a hint to use `--deleted` if there are bookmarks
+  pending deletion.
+
 ### Fixed bugs
 
 * Fixed crash on change-delete conflict resolution.

cli/src/commands/git/push.rs

@@ -393,6 +393,27 @@ pub fn cmd_git_push(
             ),
             remote = remote.as_symbol()
         );
+
+        // We only show this hint when pushing with no arguments because if the user is
+        // explicitly selecting a tracked bookmark with `--revisions`, then they'll get
+        // an error instructing them to use `--deleted`.
+        if use_default_revset {
+            let deleted_bookmarks = tx
+                .repo()
+                .view()
+                .local_remote_bookmarks(remote)
+                .filter(|(_, targets)| {
+                    targets.local_target.is_absent() && targets.remote_ref.is_tracked()
+                })
+                .count();
+
+            if deleted_bookmarks > 0 {
+                writeln!(
+                    ui.hint_default(),
+                    "You can push {deleted_bookmarks} deleted bookmark(s) with `--deleted`"
+                )?;
+            }
+        }
     }
     if bookmark_updates.is_empty() {
         writeln!(ui.status(), "Nothing changed.")?;

cli/tests/test_git_push.rs

@@ -1961,6 +1961,14 @@ fn test_git_push_deleted(subprocess: bool) {
     work_dir
         .run_jj(["bookmark", "delete", "bookmark1"])
         .success();
+    let output = work_dir.run_jj(["git", "push"]);
+    insta::assert_snapshot!(output, @r"
+    ------- stderr -------
+    Warning: No bookmarks found in the default push revset: remote_bookmarks(remote=origin)..@
+    Hint: You can push 1 deleted bookmark(s) with `--deleted`
+    Nothing changed.
+    [EOF]
+    ");
     let output = work_dir.run_jj(["git", "push", "--deleted"]);
     insta::allow_duplicates! {
     insta::assert_snapshot!(output, @r"