Rust 1.78 (#11314)

Notable things I've had to fix due to 1.78:
- Better detection of unused items
- New clippy lint (`assigning_clones`) that points out places where assignment operations with clone rhs could be replaced with more performant `clone_into`
Release Notes:

- N/A

crates/language/src/buffer.rs

@@ -2072,7 +2072,7 @@ impl Buffer {
 
     /// Override current completion triggers with the user-provided completion triggers.
     pub fn set_completion_triggers(&mut self, triggers: Vec<String>, cx: &mut ModelContext<Self>) {
-        self.completion_triggers = triggers.clone();
+        self.completion_triggers.clone_from(&triggers);
         self.completion_triggers_timestamp = self.text.lamport_clock.tick();
         self.send_operation(
             Operation::UpdateCompletionTriggers {

crates/language/src/language.rs

@@ -1126,7 +1126,7 @@ impl Language {
                 for setting in query.property_settings(ix) {
                     match setting.key.as_ref() {
                         "language" => {
-                            config.language = setting.value.clone();
+                            config.language.clone_from(&setting.value);
                         }
                         "combined" => {
                             config.combined = true;

crates/language/src/outline.rs

@@ -82,7 +82,7 @@ impl<T> Outline<T> {
         let mut prev_item_ix = 0;
         for mut string_match in matches {
             let outline_match = &self.items[string_match.candidate_id];
-            string_match.string = outline_match.text.clone();
+            string_match.string.clone_from(&outline_match.text);
 
             if is_path_query {
                 let prefix_len = self.path_candidate_prefixes[string_match.candidate_id];