cli: status: when current change has conflicts, display instructions to resolve them

cli/src/cli_util.rs

@@ -1423,47 +1423,63 @@ See https://github.com/martinvonz/jj/blob/main/docs/working-copy.md#stale-workin
                     "There are still unresolved conflicts in rebased descendants.",
                 )?;
             }
-            let root_conflicts_revset = RevsetExpression::commits(
+
+            self.report_repo_conflicts(
+                fmt.as_mut(),
+                new_repo,
                 added_conflict_commits
                     .iter()
                     .map(|commit| commit.id().clone())
                     .collect(),
-            )
+            )?;
+        }
+
+        Ok(())
+    }
+
+    pub fn report_repo_conflicts(
+        &self,
+        fmt: &mut dyn Formatter,
+        repo: &ReadonlyRepo,
+        conflicted_commits: Vec<CommitId>,
+    ) -> Result<(), CommandError> {
+        let only_one_conflicted_commit = conflicted_commits.len() == 1;
+        let root_conflicts_revset = RevsetExpression::commits(conflicted_commits)
             .roots()
-            .evaluate_programmatic(new_repo)?;
+            .evaluate_programmatic(repo)?;
 
-            let root_conflict_commits: Vec<_> = root_conflicts_revset
-                .iter()
-                .commits(new_repo.store())
-                .try_collect()?;
-            if !root_conflict_commits.is_empty() {
-                fmt.push_label("hint")?;
-                if added_conflict_commits.len() == 1 {
-                    writeln!(fmt, "To resolve the conflicts, start by updating to it:",)?;
-                } else if root_conflict_commits.len() == 1 {
-                    writeln!(
-                        fmt,
-                        "To resolve the conflicts, start by updating to the first one:",
-                    )?;
-                } else {
-                    writeln!(
-                        fmt,
-                        "To resolve the conflicts, start by updating to one of the first ones:",
-                    )?;
-                }
-                for commit in root_conflict_commits {
-                    writeln!(fmt, "  jj new {}", short_change_hash(commit.change_id()))?;
-                }
+        let root_conflict_change_ids: Vec<_> = root_conflicts_revset
+            .iter()
+            .commits(repo.store())
+            .map(|maybe_commit| maybe_commit.map(|c| c.change_id().clone()))
+            .try_collect()?;
+
+        if !root_conflict_change_ids.is_empty() {
+            fmt.push_label("hint")?;
+            if only_one_conflicted_commit {
+                writeln!(fmt, "To resolve the conflicts, start by updating to it:",)?;
+            } else if root_conflict_change_ids.len() == 1 {
                 writeln!(
                     fmt,
-                    r#"Then use `jj resolve`, or edit the conflict markers in the file directly.
-Once the conflicts are resolved, you may want inspect the result with `jj diff`.
-Then run `jj squash` to move the resolution into the conflicted commit."#,
+                    "To resolve the conflicts, start by updating to the first one:",
+                )?;
+            } else {
+                writeln!(
+                    fmt,
+                    "To resolve the conflicts, start by updating to one of the first ones:",
                 )?;
-                fmt.pop_label()?;
             }
+            for change_id in root_conflict_change_ids {
+                writeln!(fmt, "  jj new {}", short_change_hash(&change_id))?;
+            }
+            writeln!(
+                fmt,
+                r#"Then use `jj resolve`, or edit the conflict markers in the file directly.
+Once the conflicts are resolved, you may want inspect the result with `jj diff`.
+Then run `jj squash` to move the resolution into the conflicted commit."#,
+            )?;
+            fmt.pop_label()?;
         }
-
         Ok(())
     }
 

cli/src/commands/status.rs

@@ -14,6 +14,7 @@
 
 use itertools::Itertools;
 use jj_lib::repo::Repo;
+use jj_lib::revset::{RevsetExpression, RevsetFilterPredicate};
 use jj_lib::rewrite::merge_commit_trees;
 use tracing::instrument;
 
@@ -91,6 +92,16 @@ pub(crate) fn cmd_status(
             template.format(&parent, formatter)?;
             writeln!(formatter)?;
         }
+
+        let wc_revset = RevsetExpression::commit(wc_commit.id().clone());
+        // Ancestors with conflicts, excluding the current working copy commit.
+        let ancestors_conflicts = RevsetExpression::filter(RevsetFilterPredicate::HasConflict)
+            .intersection(&wc_revset.ancestors())
+            .minus(&wc_revset)
+            .evaluate_programmatic(repo.as_ref())?
+            .iter()
+            .collect();
+        workspace_command.report_repo_conflicts(formatter, repo, ancestors_conflicts)?;
     } else {
         writeln!(formatter, "No working copy")?;
     }

cli/tests/test_status_command.rs

@@ -81,3 +81,76 @@ fn test_status_filtered() {
     Parent commit: zzzzzzzz 00000000 (empty) (no description set)
     "###);
 }
+
+// See <https://github.com/martinvonz/jj/issues/3108>
+#[test]
+fn test_status_display_rebase_instructions() {
+    let test_env = TestEnvironment::default();
+    test_env.jj_cmd_ok(test_env.env_root(), &["git", "init", "repo"]);
+
+    let repo_path = test_env.env_root().join("repo");
+    let conflicted_path = repo_path.join("conflicted.txt");
+
+    // PARENT: Write the initial file
+    std::fs::write(&conflicted_path, "initial contents").unwrap();
+    test_env.jj_cmd_ok(&repo_path, &["describe", "--message", "Initial contents"]);
+
+    // CHILD1: New commit on top of <PARENT>
+    test_env.jj_cmd_ok(
+        &repo_path,
+        &["new", "--message", "First part of conflicting change"],
+    );
+    std::fs::write(&conflicted_path, "Child 1").unwrap();
+
+    // CHILD2: New commit also on top of <PARENT>
+    test_env.jj_cmd_ok(
+        &repo_path,
+        &[
+            "new",
+            "--message",
+            "Second part of conflicting change",
+            "@-",
+        ],
+    );
+    std::fs::write(&conflicted_path, "Child 2").unwrap();
+
+    // CONFLICT: New commit that is conflicted by merging <CHILD1> and <CHILD2>
+    test_env.jj_cmd_ok(&repo_path, &["new", "--message", "boom", "all:(@-)+"]);
+    // Adding more descendants to ensure we correctly find the root ancestors with
+    // conflicts, not just the parents.
+    test_env.jj_cmd_ok(&repo_path, &["new", "--message", "boom-cont"]);
+    test_env.jj_cmd_ok(&repo_path, &["new", "--message", "boom-cont-2"]);
+
+    let stdout = test_env.jj_cmd_success(&repo_path, &["log", "-r", "::@"]);
+
+    insta::assert_snapshot!(stdout, @r###"
+    @  yqosqzyt [email protected] 2001-02-03 08:05:13 93e9928b conflict
+    │  (empty) boom-cont-2
+    ◉  royxmykx [email protected] 2001-02-03 08:05:12 ac5398e8 conflict
+    │  (empty) boom-cont
+    ◉    mzvwutvl [email protected] 2001-02-03 08:05:11 be6032ca conflict
+    ├─╮  (empty) boom
+    │ ◉  kkmpptxz [email protected] 2001-02-03 08:05:10 55ce6709
+    │ │  First part of conflicting change
+    ◉ │  zsuskuln [email protected] 2001-02-03 08:05:11 ba5f8773
+    ├─╯  Second part of conflicting change
+    ◉  qpvuntsm [email protected] 2001-02-03 08:05:08 98e0dcf8
+    │  Initial contents
+    ◉  zzzzzzzz root() 00000000
+    "###);
+
+    let stdout = test_env.jj_cmd_success(&repo_path, &["status"]);
+
+    insta::assert_snapshot!(stdout, @r###"
+    The working copy is clean
+    There are unresolved conflicts at these paths:
+    conflicted.txt    2-sided conflict
+    Working copy : yqosqzyt 93e9928b (conflict) (empty) boom-cont-2
+    Parent commit: royxmykx ac5398e8 (conflict) (empty) boom-cont
+    To resolve the conflicts, start by updating to the first one:
+      jj new mzvwutvlkqwt
+    Then use `jj resolve`, or edit the conflict markers in the file directly.
+    Once the conflicts are resolved, you may want inspect the result with `jj diff`.
+    Then run `jj squash` to move the resolution into the conflicted commit.
+    "###);
+}