clippy: enable assigning_clones lint

Author: xtqqczze

Cargo.toml

@@ -134,6 +134,7 @@ jj-lib-proc-macros = { path = "lib/proc-macros", version = "0.36.0" }
 testutils = { path = "lib/testutils" }
 
 [workspace.lints.clippy]
+assigning_clones = "warn"
 borrow_as_ptr = "warn"
 cast_lossless = "warn"
 explicit_into_iter_loop = "warn"

cli/src/commands/metaedit.rs

@@ -210,8 +210,10 @@ pub(crate) fn cmd_metaedit(
                     new_author.name = name;
                     new_author.email = email;
                 } else if args.update_author {
-                    new_author.name = commit_builder.committer().name.clone();
-                    new_author.email = commit_builder.committer().email.clone();
+                    new_author.name.clone_from(&commit_builder.committer().name);
+                    new_author
+                        .email
+                        .clone_from(&commit_builder.committer().email);
                 }
                 if args.update_author_timestamp {
                     new_author.timestamp = commit_builder.committer().timestamp;

cli/src/merge_tools/mod.rs

@@ -225,7 +225,7 @@ pub fn get_external_tool_config(
         return Ok(None);
     };
     if tool.program.is_empty() {
-        tool.program = name.to_owned();
+        name.clone_into(&mut tool.program);
     };
     Ok(Some(tool))
 }

lib/src/commit_builder.rs

@@ -389,7 +389,7 @@ impl DetachedCommitBuilder {
     /// Writes new commit and makes it visible in the `mut_repo`.
     pub fn write(mut self, mut_repo: &mut MutableRepo) -> BackendResult<Commit> {
         if self.record_predecessors_in_commit {
-            self.commit.predecessors = self.predecessors.clone();
+            self.commit.predecessors.clone_from(&self.predecessors);
         }
         let commit = write_to_store(&self.store, self.commit, &self.sign_settings)?;
         // FIXME: Google's index.has_id() always returns true.
@@ -422,7 +422,7 @@ impl DetachedCommitBuilder {
     pub fn write_hidden(&self) -> BackendResult<Commit> {
         let mut commit = self.commit.clone();
         if self.record_predecessors_in_commit {
-            commit.predecessors = self.predecessors.clone();
+            commit.predecessors.clone_from(&self.predecessors);
         }
         write_to_store(&self.store, commit, &self.sign_settings)
     }

lib/src/default_index/changed_path.rs

@@ -464,7 +464,7 @@ impl CompositeChangedPathIndex {
         assert_eq!(self_start_pos + self.num_commits, other_start_pos);
         self.readonly_segments
             .extend_from_slice(&other.readonly_segments);
-        self.mutable_segment = other.mutable_segment.clone();
+        self.mutable_segment.clone_from(&other.mutable_segment);
         self.num_commits += other.num_commits;
     }