conflicts: add labels to conflicts

CHANGELOG.md

@@ -74,6 +74,9 @@ to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   colocation state (`status`) and to convert a non-colocated git repo into
   a colocated repo (`enable`) and vice-versa `disable`.
 
+* Conflict labels can now contain more information about where the sides of
+  the conflict came from. Currently, only some commands add conflict labels.
+
 ### Fixed bugs
 
 * `jj metaedit --author-timestamp` twice with the same value no longer

cli/src/commands/diffedit.rs

@@ -149,7 +149,7 @@ don't make any changes, then the operation will be aborted.",
     let base_tree = merge_commit_trees(tx.repo(), base_commits.as_slice()).block_on()?;
     let tree = target_commit.tree()?;
     let tree_id = diff_editor.edit([&base_tree, &tree], &matcher, format_instructions)?;
-    if tree_id == *target_commit.tree_id() {
+    if !tree_id.has_changes(target_commit.tree_id()) {
         writeln!(ui.status(), "Nothing changed.")?;
     } else {
         tx.repo_mut()

cli/src/commands/file/show.rs

@@ -24,6 +24,7 @@ use jj_lib::conflicts::materialize_tree_value;
 use jj_lib::file_util::copy_async_to_sync;
 use jj_lib::fileset::FilePattern;
 use jj_lib::fileset::FilesetExpression;
+use jj_lib::merged_tree::MergedTree;
 use jj_lib::repo::Repo as _;
 use jj_lib::repo_path::RepoPath;
 use pollster::FutureExt as _;
@@ -117,7 +118,7 @@ pub(crate) fn cmd_file_show(
                 path: path.to_owned(),
                 value,
             };
-            write_tree_entries(ui, &workspace_command, &template, [Ok(entry)])?;
+            write_tree_entries(ui, &workspace_command, &template, &tree, [Ok(entry)])?;
             return Ok(());
         }
     }
@@ -128,6 +129,7 @@ pub(crate) fn cmd_file_show(
         ui,
         &workspace_command,
         &template,
+        &tree,
         tree.entries_matching(matcher.as_ref())
             .map(|(path, value)| Ok((path, value?)))
             .map_ok(|(path, value)| TreeEntry { path, value }),
@@ -152,14 +154,16 @@ fn write_tree_entries(
     ui: &Ui,
     workspace_command: &WorkspaceCommandHelper,
     template: &TemplateRenderer<TreeEntry>,
+    tree: &MergedTree,
     entries: impl IntoIterator<Item = BackendResult<TreeEntry>>,
 ) -> Result<(), CommandError> {
     let repo = workspace_command.repo();
     for entry in entries {
         let entry = entry?;
         template.format(&entry, ui.stdout_formatter().as_mut())?;
         let materialized =
-            materialize_tree_value(repo.store(), &entry.path, entry.value).block_on()?;
+            materialize_tree_value(repo.store(), &entry.path, entry.value, tree.labels())
+                .block_on()?;
         match materialized {
             MaterializedTreeValue::Absent => panic!("absent values should be excluded"),
             MaterializedTreeValue::AccessDenied(err) => {
@@ -178,7 +182,12 @@ fn write_tree_entries(
                     marker_len: None,
                     merge: repo.store().merge_options().clone(),
                 };
-                materialize_merge_result(&file.contents, &mut ui.stdout_formatter(), &options)?;
+                materialize_merge_result(
+                    &file.contents,
+                    &file.labels,
+                    &mut ui.stdout_formatter(),
+                    &options,
+                )?;
             }
             MaterializedTreeValue::OtherConflict { id } => {
                 ui.stdout_formatter().write_all(id.describe().as_bytes())?;

cli/src/commands/restore.rs

@@ -164,7 +164,7 @@ pub(crate) fn cmd_restore(
     };
     let new_tree_id =
         diff_selector.select([&to_tree, &from_tree], &matcher, format_instructions)?;
-    if &new_tree_id == to_commit.tree_id() {
+    if !new_tree_id.has_changes(to_commit.tree_id()) {
         writeln!(ui.status(), "Nothing changed.")?;
     } else {
         let mut tx = workspace_command.start_transaction();

cli/src/commands/revert.rs

@@ -143,7 +143,9 @@ pub(crate) fn cmd_revert(
     {
         let old_base_tree = commit_to_revert.parent_tree(tx.repo())?;
         let old_tree = commit_to_revert.tree()?;
-        let new_tree = new_base_tree.merge(old_tree, old_base_tree).block_on()?;
+        let new_tree = new_base_tree
+            .merge_unlabeled(old_tree, old_base_tree)
+            .block_on()?;
         let new_parent_ids = parent_ids.clone();
         let new_commit = tx
             .repo_mut()

cli/src/commands/split.rs

@@ -264,7 +264,7 @@ pub(crate) fn cmd_split(
             // containing the user selected changes as the base for the merge.
             // This results in a tree with the changes the user didn't select.
             target_tree
-                .merge(target.selected_tree.clone(), target.parent_tree.clone())
+                .merge_unlabeled(target.selected_tree.clone(), target.parent_tree.clone())
                 .block_on()?
         } else {
             target_tree

cli/src/commit_templater.rs

@@ -2144,7 +2144,12 @@ impl TreeDiff {
 
     fn into_formatted<F, E>(self, show: F) -> TreeDiffFormatted<F>
     where
-        F: Fn(&mut dyn Formatter, &Store, BoxStream<CopiesTreeDiffEntry>) -> Result<(), E>,
+        F: Fn(
+            &mut dyn Formatter,
+            &Store,
+            Diff<&MergedTree>,
+            BoxStream<CopiesTreeDiffEntry>,
+        ) -> Result<(), E>,
         E: Into<TemplatePropertyError>,
     {
         TreeDiffFormatted { diff: self, show }
@@ -2159,14 +2164,21 @@ struct TreeDiffFormatted<F> {
 
 impl<F, E> Template for TreeDiffFormatted<F>
 where
-    F: Fn(&mut dyn Formatter, &Store, BoxStream<CopiesTreeDiffEntry>) -> Result<(), E>,
+    F: Fn(
+        &mut dyn Formatter,
+        &Store,
+        Diff<&MergedTree>,
+        BoxStream<CopiesTreeDiffEntry>,
+    ) -> Result<(), E>,
     E: Into<TemplatePropertyError>,
 {
     fn format(&self, formatter: &mut TemplateFormatter) -> io::Result<()> {
         let show = &self.show;
         let store = self.diff.from_tree.store();
+        let trees = Diff::new(&self.diff.from_tree, &self.diff.to_tree);
         let tree_diff = self.diff.diff_stream();
-        show(formatter.as_mut(), store, tree_diff).or_else(|err| formatter.handle_error(err.into()))
+        show(formatter.as_mut(), store, trees, tree_diff)
+            .or_else(|err| formatter.handle_error(err.into()))
     }
 }
 
@@ -2212,10 +2224,11 @@ fn builtin_tree_diff_methods<'repo>() -> CommitTemplateBuildMethodFnMap<'repo, T
                     if let Some(context) = context {
                         options.context = context;
                     }
-                    diff.into_formatted(move |formatter, store, tree_diff| {
+                    diff.into_formatted(move |formatter, store, trees, tree_diff| {
                         diff_util::show_color_words_diff(
                             formatter,
                             store,
+                            trees,
                             tree_diff,
                             path_converter,
                             &options,
@@ -2254,10 +2267,11 @@ fn builtin_tree_diff_methods<'repo>() -> CommitTemplateBuildMethodFnMap<'repo, T
                     if let Some(context) = context {
                         options.context = context;
                     }
-                    diff.into_formatted(move |formatter, store, tree_diff| {
+                    diff.into_formatted(move |formatter, store, trees, tree_diff| {
                         diff_util::show_git_diff(
                             formatter,
                             store,
+                            trees,
                             tree_diff,
                             &options,
                             conflict_marker_style,
@@ -2310,7 +2324,7 @@ fn builtin_tree_diff_methods<'repo>() -> CommitTemplateBuildMethodFnMap<'repo, T
             let path_converter = language.path_converter;
             let template = self_property
                 .map(move |diff| {
-                    diff.into_formatted(move |formatter, _store, tree_diff| {
+                    diff.into_formatted(move |formatter, _store, _trees, tree_diff| {
                         diff_util::show_diff_summary(formatter, tree_diff, path_converter)
                             .block_on()
                     })