cli: print a message about new and resolved conflicts

cli/src/cli_util.rs

@@ -28,7 +28,7 @@ use std::{iter, str};
 
 use clap::builder::{NonEmptyStringValueParser, TypedValueParser, ValueParserFactory};
 use clap::{Arg, ArgAction, ArgMatches, Command, FromArgMatches};
-use indexmap::IndexSet;
+use indexmap::{IndexMap, IndexSet};
 use itertools::Itertools;
 use jj_lib::backend::{BackendError, ChangeId, CommitId, MergedTreeId, ObjectId};
 use jj_lib::commit::Commit;
@@ -52,8 +52,8 @@ use jj_lib::repo::{
 use jj_lib::repo_path::{FsPathParseError, RepoPath};
 use jj_lib::revset::{
     DefaultSymbolResolver, Revset, RevsetAliasesMap, RevsetCommitRef, RevsetEvaluationError,
-    RevsetExpression, RevsetIteratorExt, RevsetParseContext, RevsetParseError,
-    RevsetParseErrorKind, RevsetResolutionError, RevsetWorkspaceContext,
+    RevsetExpression, RevsetFilterPredicate, RevsetIteratorExt, RevsetParseContext,
+    RevsetParseError, RevsetParseErrorKind, RevsetResolutionError, RevsetWorkspaceContext,
 };
 use jj_lib::rewrite::restore_tree;
 use jj_lib::settings::{ConfigResultExt as _, UserSettings};
@@ -1440,8 +1440,9 @@ See https://github.com/martinvonz/jj/blob/main/docs/working-copy.md#stale-workin
             writeln!(ui.stderr(), "Rebased {num_rebased} descendant commits")?;
         }
 
-        let maybe_old_wc_commit = tx
-            .base_repo()
+        let old_repo = tx.base_repo().clone();
+
+        let maybe_old_wc_commit = old_repo
             .view()
             .get_wc_commit_id(self.workspace_id())
             .map(|commit_id| tx.base_repo().store().get_commit(commit_id))
@@ -1461,6 +1462,7 @@ See https://github.com/martinvonz/jj/blob/main/docs/working-copy.md#stale-workin
             print_failed_git_export(ui, &failed_branches)?;
         }
         self.user_repo = ReadonlyUserRepo::new(tx.commit());
+        self.report_repo_changes(ui, &old_repo)?;
         if self.may_update_working_copy {
             if let Some(new_commit) = &maybe_new_wc_commit {
                 self.update_working_copy(ui, maybe_old_wc_commit.as_ref(), new_commit)?;
@@ -1480,6 +1482,70 @@ See https://github.com/martinvonz/jj/blob/main/docs/working-copy.md#stale-workin
         }
         Ok(())
     }
+
+    fn report_repo_changes(
+        &self,
+        ui: &mut Ui,
+        old_repo: &Arc<ReadonlyRepo>,
+    ) -> Result<(), CommandError> {
+        let old_view = old_repo.view();
+        let repo = self.repo().as_ref();
+        let new_view = self.repo().view();
+        let added_heads = RevsetExpression::commits(
+            new_view
+                .heads()
+                .iter()
+                .filter(|id| !old_view.heads().contains(id))
+                .cloned()
+                .collect(),
+        );
+        let removed_heads = RevsetExpression::commits(
+            old_view
+                .heads()
+                .iter()
+                .filter(|id| !new_view.heads().contains(id))
+                .cloned()
+                .collect(),
+        );
+        let conflicts = RevsetExpression::filter(RevsetFilterPredicate::HasConflict);
+        let added_conflicts_expr = removed_heads.range(&added_heads).intersection(&conflicts);
+        let removed_conflicts_expr = added_heads.range(&removed_heads).intersection(&conflicts);
+        let added_conflicts_revset = added_conflicts_expr.resolve(repo)?.evaluate(repo)?;
+        let removed_conflicts_revset = removed_conflicts_expr.resolve(repo)?.evaluate(repo)?;
+        let added_conflicts_commits: Vec<Commit> = added_conflicts_revset
+            .iter()
+            .commits(repo.store())
+            .try_collect()?;
+        let removed_conflicts_commits: Vec<Commit> = removed_conflicts_revset
+            .iter()
+            .commits(repo.store())
+            .try_collect()?;
+        let mut added_conflict_by_change_id: IndexMap<&ChangeId, &Commit> = added_conflicts_commits
+            .iter()
+            .map(|commit| (commit.change_id(), commit))
+            .collect();
+        let removed_conflict_by_change_id: IndexMap<&ChangeId, &Commit> = removed_conflicts_commits
+            .iter()
+            .map(|commit| (commit.change_id(), commit))
+            .collect();
+        // TODO: Also report new divergence and maybe resolved divergence
+        let mut fmt = ui.stderr_formatter();
+        for (change_id, old_commit) in removed_conflict_by_change_id {
+            if added_conflict_by_change_id.remove(change_id).is_some() {
+                write!(fmt, "Resolved conflicts in: ")?;
+                self.write_commit_summary(fmt.as_mut(), old_commit)?;
+                writeln!(fmt, "")?;
+            }
+        }
+        // TODO: Hint about doing `jj new <first commit with conflicts>`.
+        for (_, new_commit) in added_conflict_by_change_id {
+            write!(fmt, "New conflicts in: ")?;
+            self.write_commit_summary(fmt.as_mut(), new_commit)?;
+            writeln!(fmt, "")?;
+        }
+
+        Ok(())
+    }
 }
 
 #[must_use]

cli/tests/test_chmod_command.rs

@@ -225,6 +225,7 @@ fn test_chmod_file_dir_deletion_conflicts() {
         test_env.jj_cmd_ok(&repo_path, &["chmod", "x", "file", "-r=file_deletion"]);
     insta::assert_snapshot!(stdout, @"");
     insta::assert_snapshot!(stderr, @r###"
+    Resolved conflicts in: kmkuslsw hidden b53cf28c (conflict) (empty) file_deletion
     Working copy now at: kmkuslsw 4cc432b5 file_deletion | (conflict) file_deletion
     Parent commit      : zsuskuln c51c9c55 file | file
     Parent commit      : royxmykx 6b18b3c1 deletion | deletion

cli/tests/test_diffedit_command.rs

@@ -342,6 +342,8 @@ fn test_diffedit_merge() {
     insta::assert_snapshot!(stderr, @r###"
     Created royxmykx 2b5202ae (conflict) merge
     Rebased 1 descendant commits
+    Resolved conflicts in: yqosqzyt hidden 859c77cb (conflict) (empty) (no description set)
+    Resolved conflicts in: royxmykx hidden 77b14a4a (conflict) merge
     Working copy now at: yqosqzyt 23b1fe1b (conflict) (empty) (no description set)
     Parent commit      : royxmykx 2b5202ae (conflict) merge
     Added 0 files, modified 0 files, removed 1 files

cli/tests/test_resolve_command.rs

@@ -184,6 +184,7 @@ conflict
     );
     insta::assert_snapshot!(stdout, @"");
     insta::assert_snapshot!(stderr, @r###"
+    Resolved conflicts in: vruxwmqv hidden 0196125d (conflict) (empty) conflict
     Working copy now at: vruxwmqv ff4e8c6b conflict | (conflict) conflict
     Parent commit      : zsuskuln aa493daf a | a
     Parent commit      : royxmykx db6a4daf b | b
@@ -635,6 +636,7 @@ fn test_multiple_conflicts() {
     let (stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["resolve", "another_file"]);
     insta::assert_snapshot!(stdout, @"");
     insta::assert_snapshot!(stderr, @r###"
+    Resolved conflicts in: vruxwmqv hidden 76f01728 (conflict) (empty) conflict
     Working copy now at: vruxwmqv c3c25bce conflict | (conflict) conflict
     Parent commit      : zsuskuln de7553ef a | a
     Parent commit      : royxmykx f68bc2f0 b | b
@@ -664,6 +666,7 @@ fn test_multiple_conflicts() {
     let (stdout, stderr) = test_env.jj_cmd_ok(&repo_path, &["resolve", "--quiet", "another_file"]);
     insta::assert_snapshot!(stdout, @"");
     insta::assert_snapshot!(stderr, @r###"
+    Resolved conflicts in: vruxwmqv hidden 76f01728 (conflict) (empty) conflict
     Working copy now at: vruxwmqv fd3874cd conflict | (conflict) conflict
     Parent commit      : zsuskuln de7553ef a | a
     Parent commit      : royxmykx f68bc2f0 b | b

cli/tests/test_restore_command.rs

@@ -63,6 +63,7 @@ fn test_restore() {
     insta::assert_snapshot!(stderr, @r###"
     Created rlvkpnrz e25100af (empty) (no description set)
     Rebased 1 descendant commits
+    New conflicts in: kkmpptxz e301deb3 (conflict) (no description set)
     Working copy now at: kkmpptxz e301deb3 (conflict) (no description set)
     Parent commit      : rlvkpnrz e25100af (empty) (no description set)
     Added 0 files, modified 1 files, removed 0 files
@@ -193,6 +194,7 @@ fn test_restore_conflicted_merge() {
     insta::assert_snapshot!(stdout, @"");
     insta::assert_snapshot!(stderr, @r###"
     Created vruxwmqv b2c9c888 conflict | (conflict) (empty) conflict
+    New conflicts in: vruxwmqv b2c9c888 conflict | (conflict) (empty) conflict
     Working copy now at: vruxwmqv b2c9c888 conflict | (conflict) (empty) conflict
     Parent commit      : zsuskuln aa493daf a | a
     Parent commit      : royxmykx db6a4daf b | b
@@ -232,6 +234,7 @@ fn test_restore_conflicted_merge() {
     insta::assert_snapshot!(stdout, @"");
     insta::assert_snapshot!(stderr, @r###"
     Created vruxwmqv 4fc10820 conflict | (conflict) (empty) conflict
+    New conflicts in: vruxwmqv 4fc10820 conflict | (conflict) (empty) conflict
     Working copy now at: vruxwmqv 4fc10820 conflict | (conflict) (empty) conflict
     Parent commit      : zsuskuln aa493daf a | a
     Parent commit      : royxmykx db6a4daf b | b