gix_merge/tree/function.rs
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use crate::tree::utils::{
apply_change, perform_blob_merge, possibly_rewritten_location, rewrite_location_with_renamed_directory,
to_components, track, unique_path_in_tree, ChangeList, ChangeListRef, PossibleConflict, TrackedChange, TreeNodes,
};
use crate::tree::ConflictMapping::{Original, Swapped};
use crate::tree::{
Conflict, ConflictIndexEntry, ConflictIndexEntryPathHint, ConflictMapping, ContentMerge, Error, Options, Outcome,
Resolution, ResolutionFailure, ResolveWith,
};
use bstr::{BString, ByteSlice};
use gix_diff::tree::recorder::Location;
use gix_diff::tree_with_rewrites::Change;
use gix_hash::ObjectId;
use gix_object::tree::{EntryKind, EntryMode};
use gix_object::{tree, FindExt};
use std::borrow::Cow;
use std::convert::Infallible;
/// Perform a merge between `our_tree` and `their_tree`, using `base_tree` as merge-base.
/// Note that `base_tree` can be an empty tree to indicate 'no common ancestor between the two sides'.
///
/// * `labels` are relevant for text-merges and will be shown in conflicts.
/// * `objects` provides access to trees when diffing them.
/// * `write_blob_to_odb(content) -> Result<ObjectId, E>` writes newly merged content into the odb to obtain an id
/// that will be used in merged trees.
/// * `diff_state` is state used for diffing trees.
/// * `diff_resource_cache` is used for similarity checks.
/// * `blob_merge` is a pre-configured platform to merge any content.
/// - Note that it shouldn't be allowed to read from the worktree, given that this is a tree-merge.
/// * `options` are used to affect how the merge is performed.
///
/// ### Unbiased (Ours x Theirs == Theirs x Ours)
///
/// The algorithm is implemented so that the result is the same no matter how the sides are ordered.
///
/// ### Differences to Merge-ORT
///
/// Merge-ORT (Git) defines the desired outcomes where are merely mimicked here. The algorithms are different, and it's
/// clear that Merge-ORT is significantly more elaborate and general.
///
/// It also writes out trees once it's done with them in a form of reduction process, here an editor is used
/// to keep only the changes, to be written by the caller who receives it as part of the result.
/// This may use more memory in the worst case scenario, but in average *shouldn't* perform much worse due to the
/// natural sparsity of the editor.
///
/// Our rename-tracking also produces copy information, but we discard it and simply treat it like an addition.
///
/// Finally, our algorithm will consider reasonable solutions to merge-conflicts as conflicts that are resolved, leaving
/// only content with conflict markers as unresolved ones.
///
/// ### Performance
///
/// Note that `objects` *should* have an object cache to greatly accelerate tree-retrieval.
#[allow(clippy::too_many_arguments)]
pub fn tree<'objects, E>(
base_tree: &gix_hash::oid,
our_tree: &gix_hash::oid,
their_tree: &gix_hash::oid,
mut labels: crate::blob::builtin_driver::text::Labels<'_>,
objects: &'objects impl gix_object::FindObjectOrHeader,
mut write_blob_to_odb: impl FnMut(&[u8]) -> Result<ObjectId, E>,
diff_state: &mut gix_diff::tree::State,
diff_resource_cache: &mut gix_diff::blob::Platform,
blob_merge: &mut crate::blob::Platform,
options: Options,
) -> Result<Outcome<'objects>, Error>
where
E: Into<Box<dyn std::error::Error + Send + Sync + 'static>>,
{
let ours_needs_diff = base_tree != our_tree;
let theirs_needs_diff = base_tree != their_tree;
let _span = gix_trace::coarse!("gix_merge::tree", ?base_tree, ?our_tree, ?their_tree, ?labels);
let (mut base_buf, mut side_buf) = (Vec::new(), Vec::new());
let ancestor_tree = objects.find_tree(base_tree, &mut base_buf)?;
let mut editor = tree::Editor::new(ancestor_tree.to_owned(), objects, base_tree.kind());
let ancestor_tree = gix_object::TreeRefIter::from_bytes(&base_buf);
let tree_conflicts = options.tree_conflicts;
let mut our_changes = Vec::new();
if ours_needs_diff {
let our_tree = objects.find_tree_iter(our_tree, &mut side_buf)?;
gix_diff::tree_with_rewrites(
ancestor_tree,
our_tree,
diff_resource_cache,
diff_state,
objects,
|change| -> Result<_, Infallible> {
track(change, &mut our_changes);
Ok(gix_diff::tree_with_rewrites::Action::Continue)
},
gix_diff::tree_with_rewrites::Options {
location: Some(Location::Path),
rewrites: options.rewrites,
},
)?;
}
let mut our_tree = TreeNodes::new();
for (idx, change) in our_changes.iter().enumerate() {
our_tree.track_change(&change.inner, idx);
}
let mut their_changes = Vec::new();
if theirs_needs_diff {
let their_tree = objects.find_tree_iter(their_tree, &mut side_buf)?;
gix_diff::tree_with_rewrites(
ancestor_tree,
their_tree,
diff_resource_cache,
diff_state,
objects,
|change| -> Result<_, Infallible> {
track(change, &mut their_changes);
Ok(gix_diff::tree_with_rewrites::Action::Continue)
},
gix_diff::tree_with_rewrites::Options {
location: Some(Location::Path),
rewrites: options.rewrites,
},
)?;
}
let mut their_tree = TreeNodes::new();
for (idx, change) in their_changes.iter().enumerate() {
their_tree.track_change(&change.inner, idx);
}
let mut conflicts = Vec::new();
let mut failed_on_first_conflict = false;
let mut should_fail_on_conflict = |mut conflict: Conflict| -> bool {
if tree_conflicts.is_some() {
if let Err(failure) = conflict.resolution {
conflict.resolution = Ok(Resolution::Forced(failure));
}
}
if let Some(how) = options.fail_on_conflict {
if conflict.resolution.is_err() || conflict.is_unresolved(how) {
failed_on_first_conflict = true;
}
}
conflicts.push(conflict);
failed_on_first_conflict
};
let ((mut our_changes, mut our_tree), (mut their_changes, mut their_tree)) =
((&mut our_changes, &mut our_tree), (&mut their_changes, &mut their_tree));
let mut outer_side = Original;
if their_changes.is_empty() {
((our_changes, our_tree), (their_changes, their_tree)) = ((their_changes, their_tree), (our_changes, our_tree));
(labels.current, labels.other) = (labels.other, labels.current);
outer_side = outer_side.swapped();
}
#[derive(Debug)]
enum MatchKind {
/// A tree is supposed to be superseded by something else.
EraseTree,
/// A leaf node is superseded by a tree
EraseLeaf,
}
'outer: while their_changes.iter().rev().any(|c| !c.was_written) {
let mut segment_start = 0;
let mut last_seen_len = their_changes.len();
while segment_start != last_seen_len {
for theirs_idx in segment_start..last_seen_len {
// `their` can be a tree, and it could be used to efficiently prune child-changes as these
// trees are always rewrites with parent ids (of course we validate), so child-changes could be handled
// quickly. However, for now the benefit of having these trees is to have them as part of the match-tree
// on *our* side so that it's clear that we passed a renamed directory (by identity).
let TrackedChange {
inner: theirs,
was_written,
needs_tree_insertion,
rewritten_location,
} = &their_changes[theirs_idx];
if theirs.entry_mode().is_tree() || *was_written {
continue;
}
if needs_tree_insertion.is_some() {
their_tree.insert(theirs, theirs_idx);
}
match our_tree
.check_conflict(
rewritten_location
.as_ref()
.map_or_else(|| theirs.source_location(), |t| t.0.as_bstr()),
)
.filter(|ours| {
ours.change_idx()
.zip(needs_tree_insertion.flatten())
.map_or(true, |(ours_idx, ignore_idx)| ours_idx != ignore_idx)
&& our_tree.is_not_same_change_in_possible_conflict(theirs, ours, our_changes)
}) {
None => {
if let Some((rewritten_location, ours_idx)) = rewritten_location {
// `no_entry` to the index because that's not a conflict at all,
// but somewhat advanced rename tracking.
if should_fail_on_conflict(Conflict::with_resolution(
Resolution::SourceLocationAffectedByRename {
final_location: rewritten_location.to_owned(),
},
(&our_changes[*ours_idx].inner, theirs, Original, outer_side),
[None, None, None],
)) {
break 'outer;
};
editor.remove(to_components(theirs.location()))?;
}
apply_change(&mut editor, theirs, rewritten_location.as_ref().map(|t| &t.0))?;
their_changes[theirs_idx].was_written = true;
}
Some(candidate) => {
use crate::tree::utils::to_components_bstring_ref as toc;
debug_assert!(
rewritten_location.is_none(),
"We should probably handle the case where a rewritten location is passed down here"
);
let (ours_idx, match_kind) = match candidate {
PossibleConflict::PassedRewrittenDirectory { change_idx } => {
let ours = &our_changes[change_idx];
let location_after_passed_rename =
rewrite_location_with_renamed_directory(theirs.location(), &ours.inner);
if let Some(new_location) = location_after_passed_rename {
their_tree.remove_existing_leaf(theirs.location());
push_deferred_with_rewrite(
(theirs.clone(), Some(change_idx)),
Some((new_location, change_idx)),
their_changes,
);
} else {
apply_change(&mut editor, theirs, None)?;
their_changes[theirs_idx].was_written = true;
}
their_changes[theirs_idx].was_written = true;
continue;
}
PossibleConflict::TreeToNonTree { change_idx: Some(idx) }
if matches!(
our_changes[idx].inner,
Change::Deletion { .. } | Change::Addition { .. } | Change::Rewrite { .. }
) =>
{
(Some(idx), Some(MatchKind::EraseTree))
}
PossibleConflict::NonTreeToTree { change_idx } => (change_idx, Some(MatchKind::EraseLeaf)),
PossibleConflict::Match { change_idx: ours_idx } => (Some(ours_idx), None),
_ => (None, None),
};
let Some(ours_idx) = ours_idx else {
let ours = match candidate {
PossibleConflict::TreeToNonTree { change_idx, .. }
| PossibleConflict::NonTreeToTree { change_idx, .. } => change_idx,
PossibleConflict::Match { change_idx }
| PossibleConflict::PassedRewrittenDirectory { change_idx } => Some(change_idx),
}
.map(|idx| &mut our_changes[idx]);
if let Some(ours) = ours {
gix_trace::debug!("Turning a case we could probably handle into a conflict for now. theirs: {theirs:#?} ours: {ours:#?} kind: {match_kind:?}");
let conflict = Conflict::unknown((&ours.inner, theirs, Original, outer_side));
if let Some(ResolveWith::Ours) = tree_conflicts {
apply_our_resolution(&ours.inner, theirs, outer_side, &mut editor)?;
*match outer_side {
Original => &mut ours.was_written,
Swapped => &mut their_changes[theirs_idx].was_written,
} = true;
}
if should_fail_on_conflict(conflict) {
break 'outer;
};
} else if matches!(candidate, PossibleConflict::TreeToNonTree { .. }) {
let (mode, id) = theirs.entry_mode_and_id();
let location = theirs.location();
let renamed_location = unique_path_in_tree(
location.as_bstr(),
&editor,
their_tree,
labels.other.unwrap_or_default(),
)?;
match tree_conflicts {
None => {
editor.upsert(toc(&renamed_location), mode.kind(), id.to_owned())?;
}
Some(ResolveWith::Ours) => {
if outer_side.is_swapped() {
editor.upsert(to_components(location), mode.kind(), id.to_owned())?;
}
}
Some(ResolveWith::Ancestor) => {
// we found no matching node of 'ours', so nothing to apply here.
}
}
let conflict = Conflict::without_resolution(
ResolutionFailure::OursDirectoryTheirsNonDirectoryTheirsRenamed {
renamed_unique_path_of_theirs: renamed_location,
},
(theirs, theirs, Original, outer_side),
[
None,
None,
index_entry_at_path(
&mode.kind().into(),
&id.to_owned(),
ConflictIndexEntryPathHint::RenamedOrTheirs,
),
],
);
their_changes[theirs_idx].was_written = true;
if should_fail_on_conflict(conflict) {
break 'outer;
};
} else if matches!(candidate, PossibleConflict::NonTreeToTree { .. }) {
// We are writing on top of what was a file, a conflict we probably already saw and dealt with.
let location = theirs.location();
let (mode, id) = theirs.entry_mode_and_id();
editor.upsert(to_components(location), mode.kind(), id.to_owned())?;
their_changes[theirs_idx].was_written = true;
} else {
gix_trace::debug!("Couldn't figure out how to handle {match_kind:?} theirs: {theirs:#?} candidate: {candidate:#?}");
}
continue;
};
let ours = &our_changes[ours_idx].inner;
match (ours, theirs) {
(
Change::Modification {
previous_id,
previous_entry_mode,
id: our_id,
location: our_location,
entry_mode: our_mode,
..
},
Change::Rewrite {
source_id: their_source_id,
id: their_id,
location: their_location,
entry_mode: their_mode,
source_location,
..
},
)
| (
Change::Rewrite {
source_id: their_source_id,
id: their_id,
location: their_location,
entry_mode: their_mode,
source_location,
..
},
Change::Modification {
previous_id,
previous_entry_mode,
id: our_id,
location: our_location,
entry_mode: our_mode,
..
},
) => {
let side = if matches!(ours, Change::Modification { .. }) {
Original
} else {
Swapped
};
if let Some(merged_mode) = merge_modes(*our_mode, *their_mode) {
debug_assert_eq!(
previous_id, their_source_id,
"both refer to the same base, so should always match"
);
let their_rewritten_location = possibly_rewritten_location(
pick_our_tree(side, our_tree, their_tree),
their_location.as_ref(),
pick_our_changes(side, our_changes, their_changes),
);
let renamed_without_change = their_source_id == their_id;
let (merged_blob_id, resolution) = if renamed_without_change {
(*our_id, None)
} else {
let (our_location, our_id, our_mode, their_location, their_id, their_mode) =
match side {
Original => (
our_location,
our_id,
our_mode,
their_location,
their_id,
their_mode,
),
Swapped => (
their_location,
their_id,
their_mode,
our_location,
our_id,
our_mode,
),
};
let (merged_blob_id, resolution) = perform_blob_merge(
labels,
objects,
blob_merge,
&mut diff_state.buf1,
&mut write_blob_to_odb,
(our_location, *our_id, *our_mode),
(their_location, *their_id, *their_mode),
(source_location, *previous_id, *previous_entry_mode),
(0, outer_side),
&options,
)?;
(merged_blob_id, Some(resolution))
};
editor.remove(toc(our_location))?;
pick_our_tree(side, our_tree, their_tree)
.remove_existing_leaf(our_location.as_bstr());
let final_location = their_rewritten_location.clone();
let new_change = Change::Addition {
location: their_rewritten_location.unwrap_or_else(|| their_location.to_owned()),
relation: None,
entry_mode: merged_mode,
id: merged_blob_id,
};
if should_fail_on_conflict(Conflict::with_resolution(
Resolution::OursModifiedTheirsRenamedAndChangedThenRename {
merged_mode: (merged_mode != *their_mode).then_some(merged_mode),
merged_blob: resolution.map(|resolution| ContentMerge {
resolution,
merged_blob_id,
}),
final_location,
},
(ours, theirs, side, outer_side),
[
index_entry(previous_entry_mode, previous_id),
index_entry(our_mode, our_id),
index_entry(their_mode, their_id),
],
)) {
break 'outer;
}
// The other side gets the addition, not our side.
push_deferred(
(new_change, None),
pick_our_changes_mut(side, their_changes, our_changes),
);
} else {
match tree_conflicts {
None => {
// keep both states - 'our_location' is the previous location as well.
editor.upsert(toc(our_location), our_mode.kind(), *our_id)?;
editor.upsert(toc(their_location), their_mode.kind(), *their_id)?;
}
Some(ResolveWith::Ours) => {
editor.remove(toc(source_location))?;
if side.to_global(outer_side).is_swapped() {
editor.upsert(toc(their_location), their_mode.kind(), *their_id)?;
} else {
editor.upsert(toc(our_location), our_mode.kind(), *our_id)?;
}
}
Some(ResolveWith::Ancestor) => {}
}
if should_fail_on_conflict(Conflict::without_resolution(
ResolutionFailure::OursModifiedTheirsRenamedTypeMismatch,
(ours, theirs, side, outer_side),
[
index_entry_at_path(
previous_entry_mode,
previous_id,
ConflictIndexEntryPathHint::RenamedOrTheirs,
),
None,
index_entry_at_path(
their_mode,
their_id,
ConflictIndexEntryPathHint::RenamedOrTheirs,
),
],
)) {
break 'outer;
}
}
}
(
Change::Modification {
location,
previous_id,
previous_entry_mode,
entry_mode: our_mode,
id: our_id,
..
},
Change::Modification {
entry_mode: their_mode,
id: their_id,
..
},
) if !involves_submodule(our_mode, their_mode)
&& merge_modes(*our_mode, *their_mode).is_some()
&& our_id != their_id =>
{
let (merged_blob_id, resolution) = perform_blob_merge(
labels,
objects,
blob_merge,
&mut diff_state.buf1,
&mut write_blob_to_odb,
(location, *our_id, *our_mode),
(location, *their_id, *their_mode),
(location, *previous_id, *previous_entry_mode),
(0, outer_side),
&options,
)?;
let merged_mode = merge_modes_prev(*our_mode, *their_mode, *previous_entry_mode)
.expect("BUG: merge_modes() reports a valid mode, this one should do too");
editor.upsert(toc(location), merged_mode.kind(), merged_blob_id)?;
if should_fail_on_conflict(Conflict::with_resolution(
Resolution::OursModifiedTheirsModifiedThenBlobContentMerge {
merged_blob: ContentMerge {
resolution,
merged_blob_id,
},
},
(ours, theirs, Original, outer_side),
[
index_entry(previous_entry_mode, previous_id),
index_entry(our_mode, our_id),
index_entry(their_mode, their_id),
],
)) {
break 'outer;
};
}
(
Change::Addition {
location,
entry_mode: our_mode,
id: our_id,
..
},
Change::Addition {
entry_mode: their_mode,
id: their_id,
..
},
) if !involves_submodule(our_mode, their_mode) && our_id != their_id => {
let conflict = if let Some(merged_mode) = merge_modes(*our_mode, *their_mode) {
let side = if our_mode == their_mode || matches!(our_mode.kind(), EntryKind::Blob) {
outer_side
} else {
outer_side.swapped()
};
let (merged_blob_id, resolution) = perform_blob_merge(
labels,
objects,
blob_merge,
&mut diff_state.buf1,
&mut write_blob_to_odb,
(location, *our_id, merged_mode),
(location, *their_id, merged_mode),
(location, their_id.kind().null(), merged_mode),
(0, side),
&options,
)?;
editor.upsert(toc(location), merged_mode.kind(), merged_blob_id)?;
Conflict::with_resolution(
Resolution::OursModifiedTheirsModifiedThenBlobContentMerge {
merged_blob: ContentMerge {
resolution,
merged_blob_id,
},
},
(ours, theirs, Original, outer_side),
[None, index_entry(our_mode, our_id), index_entry(their_mode, their_id)],
)
} else {
// Actually this has a preference, as symlinks are always left in place with the other side renamed.
let (
logical_side,
label_of_side_to_be_moved,
(our_mode, our_id, our_path_hint),
(their_mode, their_id, their_path_hint),
) = if matches!(our_mode.kind(), EntryKind::Link | EntryKind::Tree) {
(
Original,
labels.other.unwrap_or_default(),
(*our_mode, *our_id, ConflictIndexEntryPathHint::Current),
(*their_mode, *their_id, ConflictIndexEntryPathHint::RenamedOrTheirs),
)
} else {
(
Swapped,
labels.current.unwrap_or_default(),
(*their_mode, *their_id, ConflictIndexEntryPathHint::RenamedOrTheirs),
(*our_mode, *our_id, ConflictIndexEntryPathHint::Current),
)
};
let tree_with_rename = pick_our_tree(logical_side, their_tree, our_tree);
let renamed_location = unique_path_in_tree(
location.as_bstr(),
&editor,
tree_with_rename,
label_of_side_to_be_moved,
)?;
let mut conflict = Conflict::without_resolution(
ResolutionFailure::OursAddedTheirsAddedTypeMismatch {
their_unique_location: renamed_location.clone(),
},
(ours, theirs, logical_side, outer_side),
[
None,
index_entry_at_path(&our_mode, &our_id, our_path_hint),
index_entry_at_path(&their_mode, &their_id, their_path_hint),
],
);
match tree_conflicts {
None => {
let new_change = Change::Addition {
location: renamed_location,
entry_mode: their_mode,
id: their_id,
relation: None,
};
editor.upsert(toc(location), our_mode.kind(), our_id)?;
tree_with_rename.remove_existing_leaf(location.as_bstr());
push_deferred(
(new_change, None),
pick_our_changes_mut(logical_side, their_changes, our_changes),
);
}
Some(resolve) => {
conflict.entries = Default::default();
match resolve {
ResolveWith::Ours => match outer_side {
Original => {
editor.upsert(toc(location), our_mode.kind(), our_id)?;
}
Swapped => {
editor.upsert(toc(location), their_mode.kind(), their_id)?;
}
},
ResolveWith::Ancestor => {
// Do nothing - this discards both sides.
// Note that one of these adds might be the result of a rename, which
// means we effectively loose the original and can't get it back as that information is degenerated.
}
}
}
}
conflict
};
if should_fail_on_conflict(conflict) {
break 'outer;
}
}
(
Change::Modification {
location,
entry_mode,
id,
previous_entry_mode,
previous_id,
},
Change::Deletion { .. },
)
| (
Change::Deletion { .. },
Change::Modification {
location,
entry_mode,
id,
previous_entry_mode,
previous_id,
},
) => {
let (label_of_side_to_be_moved, side) = if matches!(ours, Change::Modification { .. }) {
(labels.current.unwrap_or_default(), Original)
} else {
(labels.other.unwrap_or_default(), Swapped)
};
let deletion_prefaces_addition_of_directory = {
let change_on_right = match side {
Original => their_changes.get(theirs_idx + 1),
Swapped => our_changes.get(ours_idx + 1),
};
change_on_right
.map(|change| {
change.inner.entry_mode().is_tree()
&& change.inner.location() == location
&& matches!(change.inner, Change::Addition { .. })
})
.unwrap_or_default()
};
let should_break = if deletion_prefaces_addition_of_directory {
let entries = [
index_entry(previous_entry_mode, previous_id),
index_entry(entry_mode, id),
None,
];
match tree_conflicts {
None => {
let our_tree = pick_our_tree(side, our_tree, their_tree);
let renamed_path = unique_path_in_tree(
location.as_bstr(),
&editor,
our_tree,
label_of_side_to_be_moved,
)?;
editor.remove(toc(location))?;
our_tree.remove_existing_leaf(location.as_bstr());
let new_change = Change::Addition {
location: renamed_path.clone(),
relation: None,
entry_mode: *entry_mode,
id: *id,
};
let should_break = should_fail_on_conflict(Conflict::without_resolution(
ResolutionFailure::OursModifiedTheirsDirectoryThenOursRenamed {
renamed_unique_path_to_modified_blob: renamed_path,
},
(ours, theirs, side, outer_side),
entries,
));
// Since we move *our* side, our tree needs to be modified.
push_deferred(
(new_change, None),
pick_our_changes_mut(side, our_changes, their_changes),
);
should_break
}
Some(ResolveWith::Ours) => {
match side.to_global(outer_side) {
Original => {
// ours is modification
editor.upsert(toc(location), entry_mode.kind(), *id)?;
}
Swapped => {
// ours is deletion
editor.remove(toc(location))?;
}
}
should_fail_on_conflict(Conflict::without_resolution(
ResolutionFailure::OursModifiedTheirsDeleted,
(ours, theirs, side, outer_side),
entries,
))
}
Some(ResolveWith::Ancestor) => {
should_fail_on_conflict(Conflict::without_resolution(
ResolutionFailure::OursModifiedTheirsDeleted,
(ours, theirs, side, outer_side),
entries,
))
}
}
} else {
let entries = [
index_entry(previous_entry_mode, previous_id),
index_entry(entry_mode, id),
None,
];
match tree_conflicts {
None => {
editor.upsert(toc(location), entry_mode.kind(), *id)?;
}
Some(ResolveWith::Ours) => {
let ours = match outer_side {
Original => ours,
Swapped => theirs,
};
match ours {
Change::Modification { .. } => {
editor.upsert(toc(location), entry_mode.kind(), *id)?;
}
Change::Deletion { .. } => {
editor.remove(toc(location))?;
}
_ => unreachable!("parent-match assures this"),
};
}
Some(ResolveWith::Ancestor) => {}
};
should_fail_on_conflict(Conflict::without_resolution(
ResolutionFailure::OursModifiedTheirsDeleted,
(ours, theirs, side, outer_side),
entries,
))
};
if should_break {
break 'outer;
};
}
(
Change::Modification { .. },
Change::Addition {
location,
entry_mode,
id,
..
},
) if ours.location() != theirs.location() => {
match tree_conflicts {
None => {
unreachable!("modification/deletion pair should prevent modification/addition from happening")
}
Some(ResolveWith::Ancestor) => {}
Some(ResolveWith::Ours) => {
if outer_side.is_swapped() {
editor.upsert(toc(location), entry_mode.kind(), *id)?;
}
// we have already taken care of the 'root' of this -
// everything that follows can safely be ignored
}
}
}
(
Change::Rewrite {
source_location,
source_entry_mode,
source_id,
entry_mode: our_mode,
id: our_id,
location: our_location,
..
},
Change::Rewrite {
entry_mode: their_mode,
id: their_id,
location: their_location,
..
},
// NOTE: renames are only tracked among these kinds of types anyway, but we make sure.
) if our_mode.is_blob_or_symlink() && their_mode.is_blob_or_symlink() => {
let (merged_blob_id, mut resolution) = if our_id == their_id {
(*our_id, None)
} else {
let (id, resolution) = perform_blob_merge(
labels,
objects,
blob_merge,
&mut diff_state.buf1,
&mut write_blob_to_odb,
(our_location, *our_id, *our_mode),
(their_location, *their_id, *their_mode),
(source_location, *source_id, *source_entry_mode),
(1, outer_side),
&options,
)?;
(id, Some(resolution))
};
let merged_mode =
merge_modes(*our_mode, *their_mode).expect("this case was assured earlier");
if matches!(tree_conflicts, None | Some(ResolveWith::Ours)) {
editor.remove(toc(source_location))?;
our_tree.remove_existing_leaf(source_location.as_bstr());
their_tree.remove_existing_leaf(source_location.as_bstr());
}
let their_location =
possibly_rewritten_location(our_tree, their_location.as_bstr(), our_changes)
.map_or(Cow::Borrowed(their_location.as_bstr()), Cow::Owned);
let our_location =
possibly_rewritten_location(their_tree, our_location.as_bstr(), their_changes)
.map_or(Cow::Borrowed(our_location.as_bstr()), Cow::Owned);
let (our_addition, their_addition) = if our_location == their_location {
(
None,
Some(Change::Addition {
location: our_location.into_owned(),
relation: None,
entry_mode: merged_mode,
id: merged_blob_id,
}),
)
} else {
if should_fail_on_conflict(Conflict::without_resolution(
ResolutionFailure::OursRenamedTheirsRenamedDifferently {
merged_blob: resolution.take().map(|resolution| ContentMerge {
resolution,
merged_blob_id,
}),
},
(ours, theirs, Original, outer_side),
[
index_entry_at_path(
source_entry_mode,
source_id,
ConflictIndexEntryPathHint::Source,
),
index_entry_at_path(
our_mode,
&merged_blob_id,
ConflictIndexEntryPathHint::Current,
),
index_entry_at_path(
their_mode,
&merged_blob_id,
ConflictIndexEntryPathHint::RenamedOrTheirs,
),
],
)) {
break 'outer;
};
match tree_conflicts {
None => {
let our_addition = Change::Addition {
location: our_location.into_owned(),
relation: None,
entry_mode: merged_mode,
id: merged_blob_id,
};
let their_addition = Change::Addition {
location: their_location.into_owned(),
relation: None,
entry_mode: merged_mode,
id: merged_blob_id,
};
(Some(our_addition), Some(their_addition))
}
Some(ResolveWith::Ancestor) => (None, None),
Some(ResolveWith::Ours) => {
let our_addition = Change::Addition {
location: match outer_side {
Original => our_location,
Swapped => their_location,
}
.into_owned(),
relation: None,
entry_mode: merged_mode,
id: merged_blob_id,
};
(Some(our_addition), None)
}
}
};
if let Some(resolution) = resolution {
if should_fail_on_conflict(Conflict::with_resolution(
Resolution::OursModifiedTheirsModifiedThenBlobContentMerge {
merged_blob: ContentMerge {
resolution,
merged_blob_id,
},
},
(ours, theirs, Original, outer_side),
[
index_entry_at_path(
source_entry_mode,
source_id,
ConflictIndexEntryPathHint::Source,
),
index_entry_at_path(
our_mode,
&merged_blob_id,
ConflictIndexEntryPathHint::Current,
),
index_entry_at_path(
their_mode,
&merged_blob_id,
ConflictIndexEntryPathHint::RenamedOrTheirs,
),
],
)) {
break 'outer;
};
}
if let Some(addition) = our_addition {
push_deferred((addition, Some(ours_idx)), our_changes);
}
if let Some(addition) = their_addition {
push_deferred((addition, Some(theirs_idx)), their_changes);
}
}
(
Change::Deletion { .. },
Change::Rewrite {
source_location,
entry_mode: rewritten_mode,
id: rewritten_id,
location,
..
},
)
| (
Change::Rewrite {
source_location,
entry_mode: rewritten_mode,
id: rewritten_id,
location,
..
},
Change::Deletion { .. },
) if !rewritten_mode.is_commit() => {
let side = if matches!(ours, Change::Deletion { .. }) {
Original
} else {
Swapped
};
match tree_conflicts {
None | Some(ResolveWith::Ours) => {
editor.remove(toc(source_location))?;
pick_our_tree(side, our_tree, their_tree)
.remove_existing_leaf(source_location.as_bstr());
}
Some(ResolveWith::Ancestor) => {}
}
let their_rewritten_location = possibly_rewritten_location(
pick_our_tree(side, our_tree, their_tree),
location.as_ref(),
pick_our_changes(side, our_changes, their_changes),
)
.unwrap_or_else(|| location.to_owned());
let our_addition = Change::Addition {
location: their_rewritten_location,
relation: None,
entry_mode: *rewritten_mode,
id: *rewritten_id,
};
if should_fail_on_conflict(Conflict::without_resolution(
ResolutionFailure::OursDeletedTheirsRenamed,
(ours, theirs, side, outer_side),
[
None,
None,
index_entry_at_path(
rewritten_mode,
rewritten_id,
ConflictIndexEntryPathHint::RenamedOrTheirs,
),
],
)) {
break 'outer;
};
let ours_is_rewrite = side.is_swapped();
if tree_conflicts.is_none()
|| (matches!(tree_conflicts, Some(ResolveWith::Ours)) && ours_is_rewrite)
{
push_deferred(
(our_addition, None),
pick_our_changes_mut(side, their_changes, our_changes),
);
}
}
(
Change::Rewrite {
source_location,
source_entry_mode,
source_id,
entry_mode: our_mode,
id: our_id,
location,
..
},
Change::Addition {
id: their_id,
entry_mode: their_mode,
location: add_location,
..
},
)
| (
Change::Addition {
id: their_id,
entry_mode: their_mode,
location: add_location,
..
},
Change::Rewrite {
source_location,
source_entry_mode,
source_id,
entry_mode: our_mode,
id: our_id,
location,
..
},
) if !involves_submodule(our_mode, their_mode) => {
let side = if matches!(ours, Change::Rewrite { .. }) {
Original
} else {
Swapped
};
if let Some(merged_mode) = merge_modes(*our_mode, *their_mode) {
let (merged_blob_id, resolution) = if our_id == their_id {
(*our_id, None)
} else {
let (id, resolution) = perform_blob_merge(
labels,
objects,
blob_merge,
&mut diff_state.buf1,
&mut write_blob_to_odb,
(location, *our_id, *our_mode),
(location, *their_id, *their_mode),
(source_location, source_id.kind().null(), *source_entry_mode),
(0, outer_side),
&options,
)?;
(id, Some(resolution))
};
editor.remove(toc(source_location))?;
pick_our_tree(side, our_tree, their_tree).remove_leaf(source_location.as_bstr());
if let Some(resolution) = resolution {
if should_fail_on_conflict(Conflict::with_resolution(
Resolution::OursModifiedTheirsModifiedThenBlobContentMerge {
merged_blob: ContentMerge {
resolution,
merged_blob_id,
},
},
(ours, theirs, Original, outer_side),
[None, index_entry(our_mode, our_id), index_entry(their_mode, their_id)],
)) {
break 'outer;
};
}
// Because this constellation can only be found by the lookup tree, there is
// no need to put it as addition, we know it's not going to intersect on the other side.
editor.upsert(toc(location), merged_mode.kind(), merged_blob_id)?;
} else {
// We always remove the source from the tree - it might be re-added later.
let ours_is_rename =
tree_conflicts == Some(ResolveWith::Ours) && side == outer_side;
let remove_rename_source =
tree_conflicts.is_none() || ours_is_rename || add_location != source_location;
if remove_rename_source {
editor.remove(toc(source_location))?;
pick_our_tree(side, our_tree, their_tree)
.remove_leaf(source_location.as_bstr());
}
let (
logical_side,
label_of_side_to_be_moved,
(our_mode, our_id, our_path_hint),
(their_mode, their_id, their_path_hint),
) = if matches!(our_mode.kind(), EntryKind::Link | EntryKind::Tree) {
(
Original,
labels.other.unwrap_or_default(),
(*our_mode, *our_id, ConflictIndexEntryPathHint::Current),
(*their_mode, *their_id, ConflictIndexEntryPathHint::RenamedOrTheirs),
)
} else {
(
Swapped,
labels.current.unwrap_or_default(),
(*their_mode, *their_id, ConflictIndexEntryPathHint::RenamedOrTheirs),
(*our_mode, *our_id, ConflictIndexEntryPathHint::Current),
)
};
let tree_with_rename = pick_our_tree(logical_side, their_tree, our_tree);
let renamed_location = unique_path_in_tree(
location.as_bstr(),
&editor,
tree_with_rename,
label_of_side_to_be_moved,
)?;
let upsert_rename_destination = tree_conflicts.is_none() || ours_is_rename;
if upsert_rename_destination {
editor.upsert(toc(location), our_mode.kind(), our_id)?;
tree_with_rename.remove_existing_leaf(location.as_bstr());
}
let conflict = Conflict::without_resolution(
ResolutionFailure::OursAddedTheirsAddedTypeMismatch {
their_unique_location: renamed_location.clone(),
},
(ours, theirs, side, outer_side),
[
None,
index_entry_at_path(&our_mode, &our_id, our_path_hint),
index_entry_at_path(&their_mode, &their_id, their_path_hint),
],
);
if tree_conflicts.is_none() {
let new_change_with_rename = Change::Addition {
location: renamed_location,
entry_mode: their_mode,
id: their_id,
relation: None,
};
push_deferred(
(
new_change_with_rename,
Some(pick_idx(logical_side, theirs_idx, ours_idx)),
),
pick_our_changes_mut(logical_side, their_changes, our_changes),
);
}
if should_fail_on_conflict(conflict) {
break 'outer;
}
}
}
_unknown => {
debug_assert!(
match_kind.is_none()
|| (ours.location() == theirs.location()
|| ours.source_location() == theirs.source_location()),
"BUG: right now it's not known to be possible to match changes from different paths: {match_kind:?} {candidate:?}"
);
if let Some(ResolveWith::Ours) = tree_conflicts {
apply_our_resolution(ours, theirs, outer_side, &mut editor)?;
}
if should_fail_on_conflict(Conflict::unknown((ours, theirs, Original, outer_side))) {
break 'outer;
};
}
}
their_changes[theirs_idx].was_written = true;
our_changes[ours_idx].was_written = true;
}
}
}
segment_start = last_seen_len;
last_seen_len = their_changes.len();
}
((our_changes, our_tree), (their_changes, their_tree)) = ((their_changes, their_tree), (our_changes, our_tree));
(labels.current, labels.other) = (labels.other, labels.current);
outer_side = outer_side.swapped();
}
Ok(Outcome {
tree: editor,
conflicts,
failed_on_first_unresolved_conflict: failed_on_first_conflict,
})
}
fn apply_our_resolution(
local_ours: &Change,
local_theirs: &Change,
outer_side: ConflictMapping,
editor: &mut gix_object::tree::Editor<'_>,
) -> Result<(), Error> {
let ours = match outer_side {
Original => local_ours,
Swapped => local_theirs,
};
Ok(apply_change(editor, ours, None)?)
}
fn involves_submodule(a: &EntryMode, b: &EntryMode) -> bool {
a.is_commit() || b.is_commit()
}
/// Allows equal modes or prefers executables bits in case of blobs
///
/// Note that this is often not correct as the previous mode of each side should be taken into account so that:
///
/// on | on = on
/// off | off = off
/// on | off || off | on = conflict
fn merge_modes(a: EntryMode, b: EntryMode) -> Option<EntryMode> {
match (a.kind(), b.kind()) {
(_, _) if a == b => Some(a),
(EntryKind::BlobExecutable, EntryKind::BlobExecutable | EntryKind::Blob)
| (EntryKind::Blob, EntryKind::BlobExecutable) => Some(EntryKind::BlobExecutable.into()),
_ => None,
}
}
/// Use this version if there is a single common `prev` value for both `a` and `b` to detect
/// if the mode was turned on or off.
fn merge_modes_prev(a: EntryMode, b: EntryMode, prev: EntryMode) -> Option<EntryMode> {
match (a.kind(), b.kind()) {
(_, _) if a == b => Some(a),
(a @ EntryKind::BlobExecutable, b @ (EntryKind::BlobExecutable | EntryKind::Blob))
| (a @ EntryKind::Blob, b @ EntryKind::BlobExecutable) => {
let prev = prev.kind();
let changed = if a == prev { b } else { a };
Some(
match (prev, changed) {
(EntryKind::Blob, EntryKind::BlobExecutable) => EntryKind::BlobExecutable,
(EntryKind::BlobExecutable, EntryKind::Blob) => EntryKind::Blob,
_ => unreachable!("upper match already assured we only deal with blobs"),
}
.into(),
)
}
_ => None,
}
}
fn push_deferred(change_and_idx: (Change, Option<usize>), changes: &mut ChangeList) {
push_deferred_with_rewrite(change_and_idx, None, changes);
}
fn push_deferred_with_rewrite(
(change, ours_idx): (Change, Option<usize>),
new_location: Option<(BString, usize)>,
changes: &mut ChangeList,
) {
changes.push(TrackedChange {
inner: change,
was_written: false,
needs_tree_insertion: Some(ours_idx),
rewritten_location: new_location,
});
}
fn pick_our_tree<'a>(side: ConflictMapping, ours: &'a mut TreeNodes, theirs: &'a mut TreeNodes) -> &'a mut TreeNodes {
match side {
Original => ours,
Swapped => theirs,
}
}
fn pick_our_changes<'a>(
side: ConflictMapping,
ours: &'a ChangeListRef,
theirs: &'a ChangeListRef,
) -> &'a ChangeListRef {
match side {
Original => ours,
Swapped => theirs,
}
}
fn pick_idx(side: ConflictMapping, ours: usize, theirs: usize) -> usize {
match side {
Original => ours,
Swapped => theirs,
}
}
fn pick_our_changes_mut<'a>(
side: ConflictMapping,
ours: &'a mut ChangeList,
theirs: &'a mut ChangeList,
) -> &'a mut ChangeList {
match side {
Original => ours,
Swapped => theirs,
}
}
fn index_entry(mode: &gix_object::tree::EntryMode, id: &gix_hash::ObjectId) -> Option<ConflictIndexEntry> {
Some(ConflictIndexEntry {
mode: *mode,
id: *id,
path_hint: None,
})
}
fn index_entry_at_path(
mode: &gix_object::tree::EntryMode,
id: &gix_hash::ObjectId,
hint: ConflictIndexEntryPathHint,
) -> Option<ConflictIndexEntry> {
Some(ConflictIndexEntry {
mode: *mode,
id: *id,
path_hint: Some(hint),
})
}