Use dyn-ref instead of impl to impact compile times the least

Author: kiljacken

crates/ra_cargo_watch/src/lib.rs

@@ -249,7 +249,7 @@ enum CheckEvent {
 pub fn run_cargo(
     args: &[String],
     current_dir: Option<&Path>,
-    mut on_message: impl FnMut(cargo_metadata::Message) -> bool,
+    on_message: &mut dyn FnMut(cargo_metadata::Message) -> bool,
 ) -> Child {
     let mut command = Command::new("cargo");
     if let Some(current_dir) = current_dir {
@@ -325,7 +325,7 @@ impl WatchThread {
                 // which will break out of the loop, and continue the shutdown
                 let _ = message_send.send(CheckEvent::Begin);
 
-                let mut child = run_cargo(&args, Some(&workspace_root), |message| {
+                let mut child = run_cargo(&args, Some(&workspace_root), &mut |message| {
                     // Skip certain kinds of messages to only spend time on what's useful
                     match &message {
                         Message::CompilerArtifact(artifact) if artifact.fresh => return true,

crates/ra_project_model/src/cargo_workspace.rs

@@ -297,7 +297,7 @@ pub fn load_out_dirs(
     }
 
     let mut res = FxHashMap::default();
-    let mut child = run_cargo(&args, cargo_toml.parent(), |message| {
+    let mut child = run_cargo(&args, cargo_toml.parent(), &mut |message| {
         match message {
             Message::BuildScriptExecuted(message) => {
                 let package_id = message.package_id;