jj new --insert

src/commands/mod.rs

@@ -438,6 +438,7 @@ struct EditArgs {
 /// For more information, see
 /// https://github.com/martinvonz/jj/blob/main/docs/working-copy.md.
 #[derive(clap::Args, Clone, Debug)]
+#[command(group(ArgGroup::new("order").args(&["rebase_children", "insert"])))]
 struct NewArgs {
     /// Parent(s) of the new change
     #[arg(default_value = "@")]
@@ -451,6 +452,9 @@ struct NewArgs {
     /// Rebase the children of the parents onto the new change
     #[arg(long, short = 'C')]
     rebase_children: bool,
+    /// Insert the commit before the given changes
+    #[arg(long, short = 'I')]
+    insert: bool,
 }
 
 /// Move changes from one revision into another
@@ -1978,38 +1982,74 @@ fn cmd_new(ui: &mut Ui, command: &CommandHelper, args: &NewArgs) -> Result<(), C
     let commits = resolve_base_revs(&workspace_command, &args.revisions)?;
     let parent_ids = commits.iter().map(|c| c.id().clone()).collect::<Vec<_>>();
     let mut tx = workspace_command.start_transaction("new empty commit");
-    let merged_tree = merge_commit_trees(tx.base_repo().as_repo_ref(), &commits);
-    let new_commit = tx
-        .mut_repo()
-        .new_commit(
-            command.settings(),
-            parent_ids.clone(),
-            merged_tree.id().clone(),
-        )
-        .set_description(&args.message)
-        .write()?;
     let mut num_rebased = 0;
-    if args.rebase_children {
-        // Replace parents in all children by the new commit
-        let old_parents = RevsetExpression::commits(parent_ids);
-        let children = tx
+    let new_commit;
+    if args.insert {
+        // Instead of having the new commit as a child of the
+        // changes given on the command line, add it between
+        // the changes parents and the changes.
+        let grandparents = tx
             .base_workspace_helper()
-            .evaluate_revset(&old_parents.children())?
+            .evaluate_revset(&RevsetExpression::commits(parent_ids.clone()).parents())?
             .iter()
             .commits(tx.base_repo().store())
             .collect::<Result<Vec<_>, _>>()?;
-        num_rebased = children.len();
-        for child in children {
-            let commit_parents = RevsetExpression::commits(child.parent_ids().to_owned());
-            let new_parents = commit_parents.minus(&old_parents);
-            let mut new_parents = tx
+        let merged_tree = merge_commit_trees(tx.base_repo().as_repo_ref(), &grandparents);
+        let grandparent_ids = grandparents.iter().map(|c| c.id().clone()).collect();
+        new_commit = tx
+            .mut_repo()
+            .new_commit(
+                command.settings(),
+                grandparent_ids,
+                merged_tree.id().clone(),
+            )
+            .set_description(&args.message)
+            .write()?;
+        num_rebased = parent_ids.len();
+        for parent_id in parent_ids {
+            let parent_commit = tx
                 .base_workspace_helper()
-                .evaluate_revset(&new_parents)?
+                .resolve_single_rev(&parent_id.hex())?;
+            rebase_commit(
+                command.settings(),
+                tx.mut_repo(),
+                &parent_commit,
+                &[new_commit.clone()],
+            )?;
+        }
+    } else {
+        let merged_tree = merge_commit_trees(tx.base_repo().as_repo_ref(), &commits);
+        new_commit = tx
+            .mut_repo()
+            .new_commit(
+                command.settings(),
+                parent_ids.clone(),
+                merged_tree.id().clone(),
+            )
+            .set_description(&args.message)
+            .write()?;
+        if args.rebase_children {
+            // Replace parents in all children by the new commit
+            let old_parents = RevsetExpression::commits(parent_ids);
+            let children = tx
+                .base_workspace_helper()
+                .evaluate_revset(&old_parents.children())?
                 .iter()
                 .commits(tx.base_repo().store())
                 .collect::<Result<Vec<_>, _>>()?;
-            new_parents.push(new_commit.clone());
-            rebase_commit(command.settings(), tx.mut_repo(), &child, &new_parents)?;
+            num_rebased = children.len();
+            for child in children {
+                let commit_parents = RevsetExpression::commits(child.parent_ids().to_owned());
+                let new_parents = commit_parents.minus(&old_parents);
+                let mut new_parents = tx
+                    .base_workspace_helper()
+                    .evaluate_revset(&new_parents)?
+                    .iter()
+                    .commits(tx.base_repo().store())
+                    .collect::<Result<Vec<_>, _>>()?;
+                new_parents.push(new_commit.clone());
+                rebase_commit(command.settings(), tx.mut_repo(), &child, &new_parents)?;
+            }
         }
     }
     if num_rebased > 0 {

tests/test_new_command.rs

@@ -151,6 +151,46 @@ fn test_new_rebase_children() {
     "###);
 }
 
+#[test]
+fn test_new_insert() {
+    let test_env = TestEnvironment::default();
+    test_env.jj_cmd_success(test_env.env_root(), &["init", "repo", "--git"]);
+    let repo_path = test_env.env_root().join("repo");
+    setup_before_insertion(&test_env, &repo_path);
+    insta::assert_snapshot!(get_short_log_output(&test_env, &repo_path), @r###"
+    @   F
+    |\  
+    o | E
+    | o D
+    |/  
+    | o C
+    | o B
+    | o A
+    |/  
+    o root
+    "###);
+
+    let stdout = test_env.jj_cmd_success(&repo_path, &["new", "--insert", "-m", "G", "C", "F"]);
+    insta::assert_snapshot!(stdout, @r###"
+    Rebased 2 descendant commits
+    Working copy now at: ff6bbbc7b8df G
+    "###);
+    insta::assert_snapshot!(get_short_log_output(&test_env, &repo_path), @r###"
+    o F
+    | o C
+    |/  
+    @-.   G
+    |\ \  
+    o | | E
+    | o | D
+    |/ /  
+    | o B
+    | o A
+    |/  
+    o root
+    "###);
+}
+
 fn setup_before_insertion(test_env: &TestEnvironment, repo_path: &Path) {
     test_env.jj_cmd_success(repo_path, &["branch", "create", "A"]);
     test_env.jj_cmd_success(repo_path, &["commit", "-m", "A"]);