copies: add a separate diff stream item type with copy info

The goal is to have the new item type know if it represent a copy, a
rename, a deleted rename source, or a regular copy-unrelated item.

cli/src/commit_templater.rs

@@ -18,17 +18,18 @@ use std::collections::HashMap;
 use std::io;
 use std::rc::Rc;
 
+use futures::stream::BoxStream;
 use itertools::Itertools as _;
 use jj_lib::backend::{BackendResult, ChangeId, CommitId};
 use jj_lib::commit::Commit;
-use jj_lib::copies::CopyRecords;
+use jj_lib::copies::{CopiesTreeDiffEntry, CopyRecords};
 use jj_lib::extensions_map::ExtensionsMap;
 use jj_lib::fileset::{self, FilesetExpression};
 use jj_lib::git;
 use jj_lib::hex_util::to_reverse_hex;
 use jj_lib::id_prefix::IdPrefixContext;
 use jj_lib::matchers::Matcher;
-use jj_lib::merged_tree::{MergedTree, TreeDiffStream};
+use jj_lib::merged_tree::MergedTree;
 use jj_lib::object_id::ObjectId as _;
 use jj_lib::op_store::{RefTarget, RemoteRef, WorkspaceId};
 use jj_lib::repo::Repo;
@@ -1296,14 +1297,14 @@ impl TreeDiff {
         })
     }
 
-    fn diff_stream(&self) -> TreeDiffStream<'_> {
+    fn diff_stream(&self) -> BoxStream<'_, CopiesTreeDiffEntry> {
         self.from_tree
             .diff_stream_with_copies(&self.to_tree, &*self.matcher, &self.copy_records)
     }
 
     fn into_formatted<F, E>(self, show: F) -> TreeDiffFormatted<F>
     where
-        F: Fn(&mut dyn Formatter, &Store, TreeDiffStream) -> Result<(), E>,
+        F: Fn(&mut dyn Formatter, &Store, BoxStream<CopiesTreeDiffEntry>) -> Result<(), E>,
         E: Into<TemplatePropertyError>,
     {
         TreeDiffFormatted { diff: self, show }
@@ -1318,7 +1319,7 @@ struct TreeDiffFormatted<F> {
 
 impl<F, E> Template for TreeDiffFormatted<F>
 where
-    F: Fn(&mut dyn Formatter, &Store, TreeDiffStream) -> Result<(), E>,
+    F: Fn(&mut dyn Formatter, &Store, BoxStream<CopiesTreeDiffEntry>) -> Result<(), E>,
     E: Into<TemplatePropertyError>,
 {
     fn format(&self, formatter: &mut TemplateFormatter) -> io::Result<()> {

cli/src/diff_util.rs

@@ -18,19 +18,20 @@ use std::ops::Range;
 use std::path::{Path, PathBuf};
 use std::{io, mem};
 
+use futures::stream::BoxStream;
 use futures::StreamExt;
 use itertools::Itertools;
 use jj_lib::backend::{BackendError, TreeValue};
 use jj_lib::commit::Commit;
 use jj_lib::conflicts::{
     materialized_diff_stream, MaterializedTreeDiffEntry, MaterializedTreeValue,
 };
-use jj_lib::copies::CopyRecords;
+use jj_lib::copies::{CopiesTreeDiffEntry, CopyRecords};
 use jj_lib::diff::{Diff, DiffHunk};
 use jj_lib::files::{DiffLine, DiffLineHunkSide, DiffLineIterator, DiffLineNumber};
 use jj_lib::matchers::Matcher;
 use jj_lib::merge::MergedTreeValue;
-use jj_lib::merged_tree::{MergedTree, TreeDiffEntry, TreeDiffStream};
+use jj_lib::merged_tree::MergedTree;
 use jj_lib::object_id::ObjectId;
 use jj_lib::repo::Repo;
 use jj_lib::repo_path::{RepoPath, RepoPathUiConverter};
@@ -652,7 +653,7 @@ fn basic_diff_file_type(value: &MaterializedTreeValue) -> &'static str {
 pub fn show_color_words_diff(
     formatter: &mut dyn Formatter,
     store: &Store,
-    tree_diff: TreeDiffStream,
+    tree_diff: BoxStream<CopiesTreeDiffEntry>,
     path_converter: &RepoPathUiConverter,
     num_context_lines: usize,
 ) -> Result<(), DiffRenderError> {
@@ -808,7 +809,7 @@ pub fn show_file_by_file_diff(
     ui: &Ui,
     formatter: &mut dyn Formatter,
     store: &Store,
-    tree_diff: TreeDiffStream,
+    tree_diff: BoxStream<CopiesTreeDiffEntry>,
     path_converter: &RepoPathUiConverter,
     matcher: &dyn Matcher,
     copy_records: &CopyRecords,
@@ -1279,7 +1280,7 @@ pub fn show_diff_summary(
     let copied_sources = collect_copied_sources(copy_records, matcher);
 
     async {
-        while let Some(TreeDiffEntry {
+        while let Some(CopiesTreeDiffEntry {
             source: before_path,
             target: after_path,
             value: diff,
@@ -1351,7 +1352,7 @@ fn get_diff_stat(
 pub fn show_diff_stat(
     formatter: &mut dyn Formatter,
     store: &Store,
-    tree_diff: TreeDiffStream,
+    tree_diff: BoxStream<CopiesTreeDiffEntry>,
     path_converter: &RepoPathUiConverter,
     display_width: usize,
 ) -> Result<(), DiffRenderError> {
@@ -1452,7 +1453,7 @@ pub fn show_types(
     let copied_sources = collect_copied_sources(copy_records, matcher);
 
     async {
-        while let Some(TreeDiffEntry {
+        while let Some(CopiesTreeDiffEntry {
             source,
             target,
             value: diff,
@@ -1490,11 +1491,11 @@ fn diff_summary_char(value: &MergedTreeValue) -> char {
 
 pub fn show_names(
     formatter: &mut dyn Formatter,
-    mut tree_diff: TreeDiffStream,
+    mut tree_diff: BoxStream<CopiesTreeDiffEntry>,
     path_converter: &RepoPathUiConverter,
 ) -> io::Result<()> {
     async {
-        while let Some(TreeDiffEntry {
+        while let Some(CopiesTreeDiffEntry {
             target: repo_path, ..
         }) = tree_diff.next().await
         {

lib/src/conflicts.rs

@@ -17,16 +17,17 @@
 use std::io::{Read, Write};
 use std::iter::zip;
 
+use futures::stream::BoxStream;
 use futures::{try_join, Stream, StreamExt, TryStreamExt};
 use itertools::Itertools;
 use regex::bytes::{Regex, RegexBuilder};
 
 use crate::backend::{BackendError, BackendResult, CommitId, FileId, SymlinkId, TreeId, TreeValue};
+use crate::copies::CopiesTreeDiffEntry;
 use crate::diff::{Diff, DiffHunk};
 use crate::files;
 use crate::files::{ContentHunk, MergeResult};
 use crate::merge::{Merge, MergeBuilder, MergedTreeValue};
-use crate::merged_tree::{TreeDiffEntry, TreeDiffStream};
 use crate::repo_path::{RepoPath, RepoPathBuf};
 use crate::store::Store;
 
@@ -333,11 +334,11 @@ pub struct MaterializedTreeDiffEntry {
 
 pub fn materialized_diff_stream<'a>(
     store: &'a Store,
-    tree_diff: TreeDiffStream<'a>,
+    tree_diff: BoxStream<'a, CopiesTreeDiffEntry>,
 ) -> impl Stream<Item = MaterializedTreeDiffEntry> + 'a {
     tree_diff
         .map(
-            |TreeDiffEntry {
+            |CopiesTreeDiffEntry {
                  source,
                  target,
                  value,

lib/src/copies.rs

@@ -23,7 +23,8 @@ use futures::stream::BoxStream;
 use futures::Stream;
 
 use crate::backend::{BackendResult, CopyRecord};
-use crate::merged_tree::{MergedTree, TreeDiffEntry, TreeDiffStream};
+use crate::merge::MergedTreeValue;
+use crate::merged_tree::{MergedTree, TreeDiffStream};
 use crate::repo_path::{RepoPath, RepoPathBuf};
 
 /// A collection of CopyRecords.
@@ -91,19 +92,33 @@ impl<'a> CopiesTreeDiffStream<'a> {
     }
 }
 
+/// A `TreeDiffEntry` with copy information.
+pub struct CopiesTreeDiffEntry {
+    /// The source path.
+    pub source: RepoPathBuf,
+    /// The target path.
+    pub target: RepoPathBuf,
+    /// The resolved tree values if available.
+    pub value: BackendResult<(MergedTreeValue, MergedTreeValue)>,
+}
+
 impl Stream for CopiesTreeDiffStream<'_> {
-    type Item = TreeDiffEntry;
+    type Item = CopiesTreeDiffEntry;
 
     fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
         self.inner.as_mut().poll_next(cx).map(|option| {
             option.map(|diff_entry| {
                 let Some(CopyRecord { source, .. }) =
                     self.copy_records.for_target(&diff_entry.target)
                 else {
-                    return diff_entry;
+                    return CopiesTreeDiffEntry {
+                        source: diff_entry.source,
+                        target: diff_entry.target,
+                        value: diff_entry.value,
+                    };
                 };
 
-                TreeDiffEntry {
+                CopiesTreeDiffEntry {
                     source: source.clone(),
                     target: diff_entry.target,
                     value: diff_entry.value.and_then(|(_, target_value)| {

lib/src/merged_tree.rs

@@ -31,7 +31,7 @@ use itertools::{EitherOrBoth, Itertools};
 
 use crate::backend;
 use crate::backend::{BackendResult, MergedTreeId, TreeId, TreeValue};
-use crate::copies::{CopiesTreeDiffStream, CopyRecords};
+use crate::copies::{CopiesTreeDiffEntry, CopiesTreeDiffStream, CopyRecords};
 use crate::matchers::{EverythingMatcher, Matcher};
 use crate::merge::{Merge, MergeBuilder, MergedTreeVal, MergedTreeValue};
 use crate::repo_path::{RepoPath, RepoPathBuf, RepoPathComponent};
@@ -289,7 +289,7 @@ impl MergedTree {
         other: &MergedTree,
         matcher: &'a dyn Matcher,
         copy_records: &'a CopyRecords,
-    ) -> TreeDiffStream<'a> {
+    ) -> BoxStream<'a, CopiesTreeDiffEntry> {
         let stream = self.diff_stream(other, matcher);
         Box::pin(CopiesTreeDiffStream::new(
             stream,