unapply_ownership uses gitoxide merging.

Note that this at best is done for getting better merge results, it's not significant
for performance.

Author: Byron

crates/gitbutler-branch-actions/src/integration.rs

@@ -53,9 +53,7 @@ pub(crate) fn get_workspace_head(ctx: &CommandContext) -> Result<git2::Oid> {
         workspace_tree = repo.find_commit(merge_base)?.tree()?;
     } else {
         let gix_repo = ctx.gix_repository_for_merging()?;
-        let mut merge_options_fail_fast = gix_repo.tree_merge_options()?;
-        let conflict_kind = gix::merge::tree::UnresolvedConflict::Renames;
-        merge_options_fail_fast.fail_on_conflict = Some(conflict_kind);
+        let (merge_options_fail_fast, conflict_kind) = gix_repo.merge_options_fail_fast()?;
         let merge_tree_id = git2_to_gix_object_id(repo.find_commit(target.sha)?.tree_id());
         for branch in virtual_branches.iter_mut() {
             let branch_head = repo.find_commit(branch.head())?;

crates/gitbutler-branch-actions/src/virtual.rs

@@ -25,7 +25,7 @@ use gitbutler_project::access::WorktreeWritePermission;
 use gitbutler_reference::{normalize_branch_name, Refname, RemoteRefname};
 use gitbutler_repo::{
     rebase::{cherry_rebase, cherry_rebase_group},
-    LogUntil, RepositoryExt,
+    GixRepositoryExt, LogUntil, RepositoryExt,
 };
 use gitbutler_repo_actions::RepoActionsExt;
 use gitbutler_stack::{
@@ -180,25 +180,37 @@ pub fn unapply_ownership(
         .find_commit(workspace_commit_id)
         .context("failed to find target commit")?;
 
-    let base_tree = target_commit.tree().context("failed to get target tree")?;
-    let final_tree = applied_statuses.into_iter().fold(
-        target_commit.tree().context("failed to get target tree"),
-        |final_tree, status| {
-            let final_tree = final_tree?;
+    let base_tree_id = git2_to_gix_object_id(target_commit.tree_id());
+    let gix_repo = ctx.gix_repository_for_merging()?;
+    let (merge_options_fail_fast, conflict_kind) = gix_repo.merge_options_fail_fast()?;
+    let final_tree_id = applied_statuses.into_iter().try_fold(
+        git2_to_gix_object_id(target_commit.tree_id()),
+        |final_tree_id, status| -> Result<_> {
             let files = status
                 .1
                 .into_iter()
                 .map(|file| (file.path, file.hunks))
                 .collect::<Vec<(PathBuf, Vec<VirtualBranchHunk>)>>();
-            let tree_oid = gitbutler_diff::write::hunks_onto_oid(ctx, workspace_commit_id, files)?;
-            let branch_tree = repo.find_tree(tree_oid)?;
-            let mut result = repo.merge_trees(&base_tree, &final_tree, &branch_tree, None)?;
-            let final_tree_oid = result.write_tree_to(ctx.repository())?;
-            repo.find_tree(final_tree_oid)
-                .context("failed to find tree")
+            let branch_tree_id =
+                gitbutler_diff::write::hunks_onto_oid(ctx, workspace_commit_id, files)?;
+            let mut merge = gix_repo.merge_trees(
+                base_tree_id,
+                final_tree_id,
+                git2_to_gix_object_id(branch_tree_id),
+                gix_repo.default_merge_labels(),
+                merge_options_fail_fast.clone(),
+            )?;
+            if merge.has_unresolved_conflicts(conflict_kind) {
+                bail!("Tree has conflicts after merge")
+            }
+            merge
+                .tree
+                .write(|tree| gix_repo.write(tree))
+                .map_err(|err| anyhow!("Could not write merged tree: {err}"))
         },
     )?;
 
+    let final_tree = repo.find_tree(gix_to_git2_oid(final_tree_id))?;
     let final_tree_oid = gitbutler_diff::write::hunks_onto_tree(ctx, &final_tree, diff, true)?;
     let final_tree = repo
         .find_tree(final_tree_oid)
@@ -1035,9 +1047,7 @@ impl IsCommitIntegrated<'_, '_, '_> {
         }
 
         // try to merge our tree into the upstream tree
-        let mut merge_options = self.gix_repo.tree_merge_options()?;
-        let conflict_kind = gix::merge::tree::UnresolvedConflict::Renames;
-        merge_options.fail_on_conflict = Some(conflict_kind);
+        let (merge_options, conflict_kind) = self.gix_repo.merge_options_fail_fast()?;
         let mut merge_output = self
             .gix_repo
             .merge_trees(

crates/gitbutler-repo/src/repository_ext.rs

@@ -17,6 +17,7 @@ use gitbutler_oxidize::{
 };
 use gitbutler_reference::{Refname, RemoteRefname};
 use gix::fs::is_executable;
+use gix::merge::tree::{Options, UnresolvedConflict};
 use gix::objs::WriteTo;
 use tracing::instrument;
 
@@ -731,6 +732,15 @@ pub trait GixRepositoryExt: Sized {
             other: Some("theirs".into()),
         }
     }
+
+    /// Return options suitable for merging so that the merge stops immediately after the first conflict.
+    /// It also returns the conflict kind to use when checking for unresolved conflicts.
+    fn merge_options_fail_fast(
+        &self,
+    ) -> Result<(
+        gix::merge::tree::Options,
+        gix::merge::tree::UnresolvedConflict,
+    )>;
 }
 
 impl GixRepositoryExt for gix::Repository {
@@ -759,9 +769,7 @@ impl GixRepositoryExt for gix::Repository {
         our_tree: gix::ObjectId,
         their_tree: gix::ObjectId,
     ) -> Result<bool> {
-        let mut options = self.tree_merge_options()?;
-        let conflict_kind = gix::merge::tree::UnresolvedConflict::Renames;
-        options.fail_on_conflict = Some(conflict_kind);
+        let (options, conflict_kind) = self.merge_options_fail_fast()?;
         let merge_outcome = self
             .merge_trees(
                 ancestor_tree,
@@ -773,6 +781,13 @@ impl GixRepositoryExt for gix::Repository {
             .context("failed to merge trees")?;
         Ok(!merge_outcome.has_unresolved_conflicts(conflict_kind))
     }
+
+    fn merge_options_fail_fast(&self) -> Result<(Options, UnresolvedConflict)> {
+        let mut options = self.tree_merge_options()?;
+        let conflict_kind = gix::merge::tree::UnresolvedConflict::Renames;
+        options.fail_on_conflict = Some(conflict_kind);
+        Ok((options, conflict_kind))
+    }
 }
 
 type OidFilter = dyn Fn(&git2::Commit) -> Result<bool>;