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conflicts: preserve order of adds in materialized conflict

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We write conflict to the working copy by materializing them as
conflict markers in a file. When the file has been modified (or just
the mtime has changed), we parse the markers to reconstruct the
conflict. For example, let's say we see this conflict marker:

```
<<<<<<<
+++++++
b
%%%%%%%
-a
+c
>>>>>>>
```

Then we will create a hunk with ["a"] as removed and ["b", "c"] as
added.

Now, since commit b84be06c08, when we materialize conflicts, we
minimize the diff part of the marker (the `%%%%%%%` part). The problem
is that that minimization may result in a different order of the
positive conflict terms. That's particularly bad because we do the
minimization per hunk, so we can end up reconstructing an input that
never existed.

This commit fixes the bug by only considering the next add and the one
after that, and emitting either only the first with `%%%%%%%`, or both
of them, with the first one in `++++++++` and the second one in
`%%%%%%%`.

Note that the recent fix to add context to modify/delete conflicts
means that when we parse modified such conflicts, we'll always
consider them resolved, since the expected adds/removes we pass will
not match what's actually in the file. That doesn't seem so bad, and
it's not obvious what the fix should be, so I'll leave that for later.
This commit is contained in:
Martin von Zweigbergk 2023-02-17 22:29:30 -08:00 committed by Martin von Zweigbergk
parent 975350f73b
commit f70e6987b5
4 changed files with 60 additions and 39 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

3
CHANGELOG.md
View file

@ -16,6 +16,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
* Modify/delete conflicts now include context lines
[#1244](https://github.com/martinvonz/jj/issues/1244).
* Fixed a bug that could get partially resolved conflicts to be interpreted
incorrectly.
## [0.7.0] - 2023-02-16
### Breaking changes

67
lib/src/conflicts.rs
View file

@ -192,38 +192,53 @@ pub fn materialize_merge_result(
MergeHunk::Resolved(content) => {
output.write_all(&content)?;
}
MergeHunk::Conflict(ConflictHunk {
mut removes,
mut adds,
}) => {
MergeHunk::Conflict(ConflictHunk { removes, adds }) => {
output.write_all(CONFLICT_START_LINE)?;
while !removes.is_empty() && !adds.is_empty() {
let left = &removes[0];
let mut diffs = vec![];
for right in &adds {
diffs.push(
Diff::for_tokenizer(&[left, right], &find_line_ranges)
.hunks()
.collect_vec(),
);
let mut add_index = 0;
for left in removes {
if add_index == adds.len() {
// If we have no more positive terms, emit the remaining negative
// terms as snapshots.
output.write_all(CONFLICT_MINUS_LINE)?;
output.write_all(&left)?;
continue;
}
let min_diff_index = diffs
.iter()
.position_min_by_key(|diff| diff_size(diff))
.unwrap();
let diff1 =
Diff::for_tokenizer(&[&left, &adds[add_index]], &find_line_ranges)
.hunks()
.collect_vec();
// Check if the diff against the next positive term is better. Since
// we want to preserve the order of the terms, we don't match against
// any later positive terms.
if add_index < adds.len() {
let diff2 = Diff::for_tokenizer(
&[&left, &adds[add_index + 1]],
&find_line_ranges,
)
.hunks()
.collect_vec();
if diff_size(&diff2) < diff_size(&diff1) {
// If the next positive term is a better match, emit
// the current positive term as a snapshot and the next
// positive term as a diff.
output.write_all(CONFLICT_PLUS_LINE)?;
output.write_all(&adds[add_index])?;
output.write_all(CONFLICT_DIFF_LINE)?;
write_diff_hunks(&diff2, output)?;
add_index += 2;
continue;
}
}
output.write_all(CONFLICT_DIFF_LINE)?;
write_diff_hunks(&diffs[min_diff_index], output)?;
removes.remove(0);
adds.remove(min_diff_index);
write_diff_hunks(&diff1, output)?;
add_index += 1;
}
for slice in removes {
output.write_all(CONFLICT_MINUS_LINE)?;
output.write_all(&slice)?;
}
for slice in adds {
// Emit the remaining positive terms as snapshots.
for slice in &adds[add_index..] {
output.write_all(CONFLICT_PLUS_LINE)?;
output.write_all(&slice)?;
output.write_all(slice)?;
}
output.write_all(CONFLICT_END_LINE)?;
}

25
lib/tests/test_conflicts.rs
View file

@ -67,6 +67,8 @@ line 5
",
);
// The left side should come first. The diff should be use the smaller (right)
// side, and the left side should be a snapshot.
let mut conflict = Conflict {
removes: vec![file_conflict_term(&base_id)],
adds: vec![file_conflict_term(&left_id), file_conflict_term(&right_id)],
@ -77,19 +79,20 @@ line 5
line 1
line 2
<<<<<<<
%%%%%%%
-line 3
+right 3.1
+++++++
left 3.1
left 3.2
left 3.3
%%%%%%%
-line 3
+right 3.1
>>>>>>>
line 4
line 5
"###
);
// Test with the larger diff first. We still want the small diff.
// Swap the positive terms in the conflict. The diff should still use the right
// side, but now the right side should come first.
conflict.adds.reverse();
insta::assert_snapshot!(
&materialize_conflict_string(store, &path, &conflict),
@ -158,13 +161,13 @@ line 5 right
String::from_utf8(result.clone()).unwrap(),
@r###"
<<<<<<<
+++++++
line 1 left
line 2 left
%%%%%%%
-line 1
+line 1 right
line 2
+++++++
line 1 left
line 2 left
>>>>>>>
line 3
<<<<<<<
@ -179,7 +182,7 @@ line 5 right
"###
);
// TODO: The first add should always be from the left side
// The first add should always be from the left side
insta::assert_debug_snapshot!(
parse_conflict(&result, conflict.removes.len(), conflict.adds.len()),
@r###"
@ -190,8 +193,8 @@ line 5 right
"line 1\nline 2\n",
],
adds: [
"line 1 right\nline 2\n",
"line 1 left\nline 2 left\n",
"line 1 right\nline 2\n",
],
},
Resolved(
@ -259,10 +262,10 @@ line 5
line 1
line 2
<<<<<<<
%%%%%%%
-line 3
+++++++
modified
%%%%%%%
-line 3
>>>>>>>
line 4
line 5

4
tests/test_resolve_command.rs
View file

@ -425,10 +425,10 @@ fn test_edit_delete_conflict_input_files() {
std::fs::read_to_string(repo_path.join("file")).unwrap()
, @r###"
<<<<<<<
%%%%%%%
-base
+++++++
a
%%%%%%%
-base
>>>>>>>
"###);