Change .join("") to .concat() (#58200)

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable


Release Notes:

- N/A

crates/agent_ui/src/threads_archive_view.rs

@@ -1340,7 +1340,7 @@ impl PickerDelegate for ProjectPickerDelegate {
                     .ordered_paths()
                     .map(|path| path.compact().to_string_lossy().into_owned())
                     .collect::<Vec<_>>()
-                    .join("");
+                    .concat();
                 StringMatchCandidate::new(id, &combined_string)
             })
             .collect();
@@ -1376,7 +1376,7 @@ impl PickerDelegate for ProjectPickerDelegate {
                     .ordered_paths()
                     .map(|path| path.compact().to_string_lossy().into_owned())
                     .collect::<Vec<_>>()
-                    .join("");
+                    .concat();
                 StringMatchCandidate::new(id, &combined_string)
             })
             .collect();

crates/edit_prediction_cli/src/predict.rs

@@ -529,7 +529,7 @@ async fn predict_openai(
                             _ => None,
                         })
                         .collect::<Vec<_>>()
-                        .join(""),
+                        .concat(),
                 }),
                 _ => None,
             })

crates/edit_prediction_cli/src/qa.rs

@@ -221,7 +221,7 @@ pub async fn run_qa(
                     _ => None,
                 })
                 .collect::<Vec<_>>()
-                .join("")
+                .concat()
         }
         BatchProvider::Openai => {
             let client = if args.no_batch {
@@ -255,13 +255,13 @@ pub async fn run_qa(
                                     _ => None,
                                 })
                                 .collect::<Vec<_>>()
-                                .join(""),
+                                .concat(),
                         })
                     }
                     _ => None,
                 })
                 .collect::<Vec<_>>()
-                .join("")
+                .concat()
         }
     };
 

crates/edit_prediction_cli/src/reorder_patch.rs

@@ -338,7 +338,7 @@ impl ToString for Hunk {
             .iter()
             .map(|line| line.to_string() + "\n")
             .collect::<Vec<String>>()
-            .join("");
+            .concat();
         format!("{header}\n{lines}")
     }
 }

crates/edit_prediction_cli/src/repair.rs

@@ -367,7 +367,7 @@ pub async fn run_repair(
                     _ => None,
                 })
                 .collect::<Vec<_>>()
-                .join("")
+                .concat()
         }
         BatchProvider::Openai => {
             let client = if args.no_batch {
@@ -414,13 +414,13 @@ pub async fn run_repair(
                                     _ => None,
                                 })
                                 .collect::<Vec<_>>()
-                                .join(""),
+                                .concat(),
                         })
                     }
                     _ => None,
                 })
                 .collect::<Vec<_>>()
-                .join("")
+                .concat()
         }
     };
 

crates/editor/src/inlays/inlay_hints.rs

@@ -2324,8 +2324,8 @@ pub mod tests {
         fs.insert_tree(
                 path!("/a"),
                 json!({
-                    "main.rs": format!("fn main() {{\n{}\n}}", (0..501).map(|i| format!("let i = {i};\n")).collect::<Vec<_>>().join("")),
-                    "other.rs": format!("fn main() {{\n{}\n}}", (0..501).map(|j| format!("let j = {j};\n")).collect::<Vec<_>>().join("")),
+                    "main.rs": format!("fn main() {{\n{}\n}}", (0..501).map(|i| format!("let i = {i};\n")).collect::<String>()),
+                    "other.rs": format!("fn main() {{\n{}\n}}", (0..501).map(|j| format!("let j = {j};\n")).collect::<String>()),
                 }),
             )
             .await;
@@ -2693,7 +2693,7 @@ pub mod tests {
         fs.insert_tree(
             path!("/a"),
             json!({
-                "main.rs": format!("fn main() {{\n{}\n}}", (0..200).map(|i| format!("let i = {i};\n")).collect::<Vec<_>>().join("")),
+                "main.rs": format!("fn main() {{\n{}\n}}", (0..200).map(|i| format!("let i = {i};\n")).collect::<String>()),
                 "lib.rs": r#"let a = 1;
 let b = 2;
 let c = 3;"#
@@ -2940,8 +2940,8 @@ let c = 3;"#
         fs.insert_tree(
             path!("/a"),
             json!({
-                "main.rs": format!("fn main() {{\n{}\n}}", (0..501).map(|i| format!("let i = {i};\n")).collect::<Vec<_>>().join("")),
-                "other.rs": format!("fn main() {{\n{}\n}}", (0..501).map(|j| format!("let j = {j};\n")).collect::<Vec<_>>().join("")),
+                "main.rs": format!("fn main() {{\n{}\n}}", (0..501).map(|i| format!("let i = {i};\n")).collect::<String>()),
+                "other.rs": format!("fn main() {{\n{}\n}}", (0..501).map(|j| format!("let j = {j};\n")).collect::<String>()),
             }),
         )
         .await;

crates/editor/src/items.rs

@@ -1786,7 +1786,7 @@ impl SearchableItem for Editor {
         let text: Cow<_> = if text.len() == 1 {
             text.first().cloned().unwrap().into()
         } else {
-            let joined_chunks = text.join("");
+            let joined_chunks = text.concat();
             joined_chunks.into()
         };
 
@@ -1818,7 +1818,7 @@ impl SearchableItem for Editor {
                     let text: Cow<_> = if text.len() == 1 {
                         text.first().cloned().unwrap().into()
                     } else {
-                        let joined_chunks = text.join("");
+                        let joined_chunks = text.concat();
                         joined_chunks.into()
                     };
 

crates/git_ui/src/git_panel.rs

@@ -2582,7 +2582,7 @@ impl GitPanel {
                 }
             })
             .collect::<Vec<_>>()
-            .join("");
+            .concat();
 
         if compressed.len() <= max_bytes {
             return compressed;

crates/gpui_macos/src/keyboard.rs

@@ -106,7 +106,7 @@ impl MacKeyboardMapper {
 //
 // These mappings were generated by running https://github.com/ConradIrwin/keyboard-inspector, tidying up the
 // output to remove languages with no mappings and other oddities, and converting it to a less verbose representation with:
-//  jq -s 'map(to_entries | map({key: .key, value: [(.value | to_entries | map(.key) | join("")), (.value | to_entries | map(.value) | join(""))]}) | from_entries) | add'
+//  jq -s 'map(to_entries | map({key: .key, value: [(.value | to_entries | map(.key) | concat()), (.value | to_entries | map(.value) | concat())]}) | from_entries) | add'
 // From there I used multi-cursor to produce this match statement.
 fn get_key_equivalents(layout_id: &str) -> Option<HashMap<char, char>> {
     let mappings: &[(char, char)] = match layout_id {

crates/open_router/src/open_router.rs

@@ -305,7 +305,7 @@ impl MessageContent {
                     }
                 })
                 .collect::<Vec<_>>()
-                .join(""),
+                .concat(),
         }
     }
 }

crates/recent_projects/src/recent_projects.rs

@@ -981,7 +981,7 @@ impl PickerDelegate for RecentProjectsDelegate {
                     .ordered_paths()
                     .map(|path| path.compact().to_string_lossy().into_owned())
                     .collect::<Vec<_>>()
-                    .join("");
+                    .concat();
                 StringMatchCandidate::new(id, &combined_string)
             })
             .collect();
@@ -1006,7 +1006,7 @@ impl PickerDelegate for RecentProjectsDelegate {
                     .ordered_paths()
                     .map(|path| path.compact().to_string_lossy().into_owned())
                     .collect::<Vec<_>>()
-                    .join("");
+                    .concat();
                 StringMatchCandidate::new(id, &combined_string)
             })
             .collect();

crates/recent_projects/src/sidebar_recent_projects.rs

@@ -203,7 +203,7 @@ impl PickerDelegate for SidebarRecentProjectsDelegate {
                     .ordered_paths()
                     .map(|path| path.compact().to_string_lossy().into_owned())
                     .collect::<Vec<_>>()
-                    .join("");
+                    .concat();
                 StringMatchCandidate::new(id, &combined_string)
             })
             .collect();

crates/repl/src/notebook/cell.rs

@@ -176,7 +176,7 @@ impl Cell {
                 source,
                 ..
             } => {
-                let source = source.join("");
+                let source = source.concat();
 
                 let entity = cx.new(|cx| {
                     MarkdownCell::new(
@@ -198,7 +198,7 @@ impl Cell {
                 source,
                 outputs,
             } => {
-                let text = source.join("");
+                let text = source.concat();
                 let outputs = convert_outputs(outputs, window, cx);
 
                 Cell::Code(cx.new(|cx| {
@@ -223,7 +223,7 @@ impl Cell {
             } => Cell::Raw(cx.new(|_| RawCell {
                 id: id.clone(),
                 metadata: metadata.clone(),
-                source: source.join(""),
+                source: source.concat(),
                 selected: false,
                 cell_position: None,
             })),

crates/tasks_ui/src/modal.rs

@@ -464,7 +464,7 @@ impl PickerDelegate for TasksModalDelegate {
                     .iter()
                     .map(|tag| format!("\n#{}", tag))
                     .collect::<Vec<_>>()
-                    .join("")
+                    .concat()
                     .as_str(),
             );
         }

crates/terminal_view/src/terminal_view.rs

@@ -14,7 +14,6 @@ use gpui::{
     Pixels, Point as GpuiPoint, Render, ScrollWheelEvent, Styled, Subscription, Task, TaskExt,
     WeakEntity, actions, anchored, deferred, div,
 };
-use itertools::Itertools;
 use menu;
 use persistence::TerminalDb;
 use project::{Project, ProjectEntryId, search::SearchQuery};
@@ -927,7 +926,10 @@ impl TerminalView {
     }
 
     pub fn add_paths_to_terminal(&self, paths: &[PathBuf], window: &mut Window, cx: &mut App) {
-        let mut text = paths.iter().map(|path| format!(" {path:?}")).join("");
+        let mut text = paths
+            .iter()
+            .map(|path| format!(" {path:?}"))
+            .collect::<String>();
         text.push(' ');
         window.focus(&self.focus_handle(cx), cx);
         self.terminal.update(cx, |terminal, _| {

crates/vim/src/mode_indicator.rs

@@ -83,7 +83,7 @@ impl ModeIndicator {
                     .map(|count| format!("{}", count)),
             )
             .collect::<Vec<_>>()
-            .join("")
+            .concat()
     }
 }