git: give a deleted file's PATCH_FILE record no new path

crates/git/src/diffs.rs

@@ -1171,6 +1171,15 @@ fn record_old_path(change: &Change) -> Vec<u8> {
     if old.is_empty() { new } else { old }
 }
 
+/// The new path a `PATCH_FILE` record reports: none when there is no new
+/// side, as for a deletion.
+fn record_new_path(change: &Change) -> Vec<u8> {
+    if change.new.is_none() {
+        return Vec::new();
+    }
+    change_new_path(change)
+}
+
 /// Split a rename's NUL-joined path back into (old, new).
 fn rename_paths(change: &Change) -> (Vec<u8>, Vec<u8>) {
     if change.st == b'R'
@@ -1751,7 +1760,7 @@ impl RepoHandle {
                         similarity: change.similarity,
                         flags: file_flags,
                         old_path: &crate::escape_bstr(&record_old_path(change)),
-                        new_path: &crate::escape_bstr(&change_new_path(change)),
+                        new_path: &crate::escape_bstr(&record_new_path(change)),
                     },
                 );
                 if !binary {

crates/server/src/yas_git.rs

@@ -2182,6 +2182,49 @@ mod tests {
         }
     }
 
+    #[test]
+    fn structured_patch_of_a_deletion_encodes() {
+        let directory = tempfile::tempdir().unwrap();
+        git(directory.path(), &["init", "-q"]);
+        std::fs::write(directory.path().join("gone.txt"), b"gone\n").unwrap();
+        git(directory.path(), &["add", "gone.txt"]);
+        std::fs::remove_file(directory.path().join("gone.txt")).unwrap();
+        let (repository, _) = yas_git::native::open_path(directory.path()).unwrap();
+        let page = run_query(
+            Some(&repository),
+            yas_wire::schema::git::OBJECT_SHA1 as u8,
+            &query(wire::QueryBody::Patch {
+                left: wire::QueryEndpoint::Index,
+                right: wire::QueryEndpoint::Worktree,
+                path: None,
+                context_lines: 3,
+                rename_threshold: 0,
+                max_bytes: 1024 * 1024,
+                flags: 0,
+            }),
+            None,
+            &yas_git::Cancel::default(),
+        )
+        .unwrap();
+        let [QueryItem::Record(file), QueryItem::Record(row)] = page.records.as_slice() else {
+            panic!("unexpected deletion patch page: {:?}", page.records);
+        };
+        assert_eq!(
+            file,
+            &wire::QueryRecord::PatchFile(wire::PatchFileRecord {
+                status: yas_wire::schema::git::DIFF_DELETED as u8,
+                similarity_percent: 0,
+                flags: 0,
+                old_path: Some(fs_wire::Path {
+                    components: vec![b"gone.txt".to_vec()],
+                }),
+                new_path: None,
+            })
+        );
+        file.encode_typed().unwrap();
+        row.encode_typed().unwrap();
+    }
+
     #[test]
     fn typed_queries_cover_repository_reads_without_exposing_legacy_packets() {
         let directory = tempfile::tempdir().unwrap();