rewrite: add support for rebasing descendants of multiple rewritten commits

I plan to use this for rebasing descendants of rewritten remote
branches (on fetch).

Cargo.lock

@@ -531,6 +531,7 @@ dependencies = [
  "indoc",
  "itertools 0.10.1",
  "jujutsu-lib",
+ "maplit",
  "pest",
  "pest_derive",
  "protobuf",

Cargo.toml

@@ -32,6 +32,7 @@ hex = "0.4.2"
 indoc = "1.0.3"
 itertools = "0.10.1"
 jujutsu-lib = { version = "=0.2.0", path = "lib"}
+maplit = "1.0.2"
 pest = "2.1.3"
 pest_derive = "2.1.0"
 protobuf = { version = "2.22.1", features = ["with-bytes"] }

lib/src/rewrite.rs

@@ -15,7 +15,6 @@
 use std::collections::{HashMap, HashSet};
 
 use itertools::Itertools;
-use maplit::hashmap;
 
 use crate::backend::CommitId;
 use crate::commit::Commit;
@@ -120,10 +119,8 @@ impl<'settings, 'repo> DescendantRebaser<'settings, 'repo> {
     pub fn new(
         settings: &'settings UserSettings,
         mut_repo: &'repo mut MutableRepo,
-        old_parent_id: CommitId,
+        replacements: HashMap<CommitId, Vec<CommitId>>,
-        new_parent_ids: Vec<CommitId>,
     ) -> DescendantRebaser<'settings, 'repo> {
-        let replacements = hashmap! { old_parent_id => new_parent_ids};
         let old_commits_expression =
             RevsetExpression::commits(replacements.keys().cloned().collect());
         let new_commits_expression =

lib/tests/test_rewrite.rs

@@ -19,6 +19,7 @@ use jujutsu_lib::repo_path::RepoPath;
 use jujutsu_lib::rewrite::{DescendantRebaser, RebasedDescendant};
 use jujutsu_lib::testutils;
 use jujutsu_lib::testutils::CommitGraphBuilder;
+use maplit::hashmap;
 use test_case::test_case;
 
 fn assert_in_place(rebased: Option<RebasedDescendant>, expected_old_commit: &Commit) {
@@ -83,8 +84,9 @@ fn test_rebase_descendants_sideways(use_git: bool) {
     let mut rebaser = DescendantRebaser::new(
         &settings,
         tx.mut_repo(),
-        commit2.id().clone(),
+        hashmap! {
-        vec![commit6.id().clone()],
+            commit2.id().clone() => vec![commit6.id().clone()]
+        },
     );
     let new_commit3 = assert_rebased(rebaser.rebase_next(), &commit3, &[commit6.id().clone()]);
     assert_rebased(rebaser.rebase_next(), &commit4, &[new_commit3.id().clone()]);
@@ -126,8 +128,10 @@ fn test_rebase_descendants_forward(use_git: bool) {
     let mut rebaser = DescendantRebaser::new(
         &settings,
         tx.mut_repo(),
-        commit2.id().clone(),
+        hashmap! {
-        vec![commit6.id().clone()],
+            commit2.id().clone() =>
+            vec![commit6.id().clone()]
+        },
     );
     assert_rebased(rebaser.rebase_next(), &commit3, &[commit6.id().clone()]);
     assert_ancestor(rebaser.rebase_next(), &commit4);
@@ -162,8 +166,9 @@ fn test_rebase_descendants_backward(use_git: bool) {
     let mut rebaser = DescendantRebaser::new(
         &settings,
         tx.mut_repo(),
-        commit3.id().clone(),
+        hashmap! {
-        vec![commit2.id().clone()],
+            commit3.id().clone() => vec![commit2.id().clone()]
+        },
     );
     assert_rebased(rebaser.rebase_next(), &commit4, &[commit2.id().clone()]);
     assert!(rebaser.rebase_next().is_none());
@@ -200,8 +205,9 @@ fn test_rebase_descendants_internal_merge(use_git: bool) {
     let mut rebaser = DescendantRebaser::new(
         &settings,
         tx.mut_repo(),
-        commit2.id().clone(),
+        hashmap! {
-        vec![commit6.id().clone()],
+            commit2.id().clone() => vec![commit6.id().clone()]
+        },
     );
     let new_commit3 = assert_rebased(rebaser.rebase_next(), &commit3, &[commit6.id().clone()]);
     let new_commit4 = assert_rebased(rebaser.rebase_next(), &commit4, &[commit6.id().clone()]);
@@ -245,8 +251,9 @@ fn test_rebase_descendants_external_merge(use_git: bool) {
     let mut rebaser = DescendantRebaser::new(
         &settings,
         tx.mut_repo(),
-        commit3.id().clone(),
+        hashmap! {
-        vec![commit6.id().clone()],
+            commit3.id().clone() => vec![commit6.id().clone()]
+        },
     );
     assert_rebased(
         rebaser.rebase_next(),
@@ -283,8 +290,9 @@ fn test_rebase_descendants_degenerate_merge(use_git: bool) {
     let mut rebaser = DescendantRebaser::new(
         &settings,
         tx.mut_repo(),
-        commit2.id().clone(),
+        hashmap! {
-        vec![commit1.id().clone()],
+            commit2.id().clone() => vec![commit1.id().clone()]
+        },
     );
     assert_rebased(rebaser.rebase_next(), &commit4, &[commit3.id().clone()]);
     assert!(rebaser.rebase_next().is_none());
@@ -321,8 +329,9 @@ fn test_rebase_descendants_widen_merge(use_git: bool) {
     let mut rebaser = DescendantRebaser::new(
         &settings,
         tx.mut_repo(),
-        commit5.id().clone(),
+        hashmap! {
-        vec![commit2.id().clone(), commit3.id().clone()],
+            commit5.id().clone() => vec![commit2.id().clone(), commit3.id().clone()]
+        },
     );
     assert_rebased(
         rebaser.rebase_next(),
@@ -339,6 +348,132 @@ fn test_rebase_descendants_widen_merge(use_git: bool) {
     tx.discard();
 }
 
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
+fn test_rebase_descendants_multiple_sideways(use_git: bool) {
+    let settings = testutils::user_settings();
+    let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
+
+    // Commit 2 and commit 4 were both replaced by commit 6. Commit 3 and commit 5
+    // should get rebased onto it.
+    //
+    // 3 5
+    // 2 4 6
+    // | |/
+    // |/
+    // 1
+    let mut tx = repo.start_transaction("test");
+    let mut graph_builder = CommitGraphBuilder::new(&settings, tx.mut_repo());
+    let commit1 = graph_builder.initial_commit();
+    let commit2 = graph_builder.commit_with_parents(&[&commit1]);
+    let commit3 = graph_builder.commit_with_parents(&[&commit2]);
+    let commit4 = graph_builder.commit_with_parents(&[&commit1]);
+    let commit5 = graph_builder.commit_with_parents(&[&commit4]);
+    let commit6 = graph_builder.commit_with_parents(&[&commit1]);
+
+    let mut rebaser = DescendantRebaser::new(
+        &settings,
+        tx.mut_repo(),
+        hashmap! {
+            commit2.id().clone() => vec![commit6.id().clone()],
+            commit4.id().clone() => vec![commit6.id().clone()],
+        },
+    );
+    assert_rebased(rebaser.rebase_next(), &commit3, &[commit6.id().clone()]);
+    assert_rebased(rebaser.rebase_next(), &commit5, &[commit6.id().clone()]);
+    assert!(rebaser.rebase_next().is_none());
+    assert_eq!(rebaser.rebased().len(), 2);
+
+    tx.discard();
+}
+
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
+fn test_rebase_descendants_multiple_swap(use_git: bool) {
+    let settings = testutils::user_settings();
+    let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
+
+    // Commit 2 was replaced by commit 4 and commit 4 was replaced by commit 2.
+    // Commit 3 and commit 5 should swap places.
+    //
+    // 3 5
+    // 2 4
+    // |/
+    // 1
+    let mut tx = repo.start_transaction("test");
+    let mut graph_builder = CommitGraphBuilder::new(&settings, tx.mut_repo());
+    let commit1 = graph_builder.initial_commit();
+    let commit2 = graph_builder.commit_with_parents(&[&commit1]);
+    let commit3 = graph_builder.commit_with_parents(&[&commit2]);
+    let commit4 = graph_builder.commit_with_parents(&[&commit1]);
+    let commit5 = graph_builder.commit_with_parents(&[&commit4]);
+
+    let mut rebaser = DescendantRebaser::new(
+        &settings,
+        tx.mut_repo(),
+        hashmap! {
+            commit2.id().clone() => vec![commit4.id().clone()],
+            commit4.id().clone() => vec![commit2.id().clone()],
+        },
+    );
+    assert_rebased(rebaser.rebase_next(), &commit3, &[commit4.id().clone()]);
+    assert_rebased(rebaser.rebase_next(), &commit5, &[commit2.id().clone()]);
+    assert!(rebaser.rebase_next().is_none());
+    assert_eq!(rebaser.rebased().len(), 2);
+
+    tx.discard();
+}
+
+#[test_case(false ; "local backend")]
+#[test_case(true ; "git backend")]
+fn test_rebase_descendants_multiple_forward_and_backward(use_git: bool) {
+    let settings = testutils::user_settings();
+    let (_temp_dir, repo) = testutils::init_repo(&settings, use_git);
+
+    // Commit 2 was replaced by commit 4 and commit 6 was replaced by commit 3.
+    // Commit 7 should be rebased onto commit 3. Commit 8 should be rebased onto
+    // commit 4. Commits 3-4 should be left alone since they're ancestors of 4.
+    // Commit 5 should be left alone since its already in place (as a descendant of
+    // 4).
+    //
+    // 7
+    // 6
+    // 5
+    // 4
+    // 3 8
+    // |/
+    // 2
+    // 1
+    let mut tx = repo.start_transaction("test");
+    let mut graph_builder = CommitGraphBuilder::new(&settings, tx.mut_repo());
+    let commit1 = graph_builder.initial_commit();
+    let commit2 = graph_builder.commit_with_parents(&[&commit1]);
+    let commit3 = graph_builder.commit_with_parents(&[&commit2]);
+    let commit4 = graph_builder.commit_with_parents(&[&commit3]);
+    let commit5 = graph_builder.commit_with_parents(&[&commit4]);
+    let commit6 = graph_builder.commit_with_parents(&[&commit5]);
+    let commit7 = graph_builder.commit_with_parents(&[&commit6]);
+    let commit8 = graph_builder.commit_with_parents(&[&commit2]);
+
+    let mut rebaser = DescendantRebaser::new(
+        &settings,
+        tx.mut_repo(),
+        hashmap! {
+            commit2.id().clone() => vec![commit4.id().clone()],
+            commit6.id().clone() => vec![commit3.id().clone()],
+        },
+    );
+    assert_ancestor(rebaser.rebase_next(), &commit3);
+    assert_ancestor(rebaser.rebase_next(), &commit4);
+    assert_in_place(rebaser.rebase_next(), &commit5);
+    assert_rebased(rebaser.rebase_next(), &commit7, &[commit3.id().clone()]);
+    assert_rebased(rebaser.rebase_next(), &commit8, &[commit4.id().clone()]);
+    assert!(rebaser.rebase_next().is_none());
+    assert_eq!(rebaser.rebased().len(), 2);
+
+    tx.discard();
+}
+
 #[test_case(false ; "local backend")]
 #[test_case(true ; "git backend")]
 fn test_rebase_descendants_contents(use_git: bool) {
@@ -377,8 +512,9 @@ fn test_rebase_descendants_contents(use_git: bool) {
     let mut rebaser = DescendantRebaser::new(
         &settings,
         tx.mut_repo(),
-        commit2.id().clone(),
+        hashmap! {
-        vec![commit4.id().clone()],
+            commit2.id().clone() => vec![commit4.id().clone()]
+        },
     );
     rebaser.rebase_all();
     let rebased = rebaser.rebased();

src/commands.rs

@@ -59,6 +59,7 @@ use jujutsu_lib::transaction::Transaction;
 use jujutsu_lib::tree::{Diff, DiffSummary};
 use jujutsu_lib::working_copy::{CheckoutStats, WorkingCopy};
 use jujutsu_lib::{conflicts, files, git, revset};
+use maplit::hashmap;
 use pest::Parser;
 
 use self::chrono::{FixedOffset, TimeZone, Utc};
@@ -2656,8 +2657,9 @@ fn cmd_rebase(
         let mut rebaser = DescendantRebaser::new(
             ui.settings(),
             tx.mut_repo(),
-            old_commit.id().clone(),
+            hashmap! {
-            vec![new_commit.id().clone()],
+                old_commit.id().clone() => vec![new_commit.id().clone()]
+            },
         );
         rebaser.rebase_all();
         let num_rebased = rebaser.rebased().len() + 1;
@@ -2673,8 +2675,9 @@ fn cmd_rebase(
         let mut rebaser = DescendantRebaser::new(
             ui.settings(),
             tx.mut_repo(),
-            old_commit.id().clone(),
+            hashmap! {
-            old_commit.parent_ids(),
+                old_commit.id().clone() => old_commit.parent_ids()
+            },
         );
         rebaser.rebase_all();
         let num_rebased = rebaser.rebased().len();