Add general refactorings (#3996)

crates/nu-command/src/commands/platform/clear.rs

@@ -22,12 +22,12 @@ impl WholeStreamCommand for Clear {
     fn run(&self, _: CommandArgs) -> Result<InputStream, ShellError> {
         if cfg!(windows) {
             Command::new("cmd")
-                .args(&["/C", "cls"])
+                .args(["/C", "cls"])
                 .status()
                 .expect("failed to execute process");
         } else if cfg!(unix) {
             Command::new("/bin/sh")
-                .args(&["-c", "clear"])
+                .args(["-c", "clear"])
                 .status()
                 .expect("failed to execute process");
         }

crates/nu-command/src/commands/platform/clip.rs

@@ -51,7 +51,7 @@ pub fn clip(args: CommandArgs) -> Result<ActionStream, ShellError> {
 
         if !values.is_empty() {
             let mut first = true;
-            for i in values.iter() {
+            for i in &values {
                 if !first {
                     new_copy_data.push('\n');
                 } else {

crates/nu-command/src/commands/platform/du.rs

@@ -99,7 +99,7 @@ fn du(args: CommandArgs) -> Result<ActionStream, ShellError> {
 
     let exclude = args.exclude.map_or(Ok(None), move |x| {
         Pattern::new(&x.item)
-            .map(Option::Some)
+            .map(Some)
             .map_err(|e| ShellError::labeled_error(e.msg, "glob error", x.tag.clone()))
     })?;
 
@@ -148,11 +148,10 @@ fn du(args: CommandArgs) -> Result<ActionStream, ShellError> {
                     output.push(Ok(ReturnSuccess::Value(
                         DirInfo::new(p, &params, max_depth, ctrl_c.clone()).into(),
                     )));
-                } else {
-                    for v in FileInfo::new(p, deref, tag.clone()).into_iter() {
-                        output.push(Ok(ReturnSuccess::Value(v.into())));
-                    }
+                } else if let Ok(v) = FileInfo::new(p, deref, tag.clone()) {
+                    output.push(Ok(ReturnSuccess::Value(v.into())));
                 }
+
                 output
             }
             Err(e) => vec![Err(e)],

crates/nu-command/src/commands/platform/exec.rs

@@ -80,7 +80,7 @@ fn exec(args: CommandArgs) -> Result<OutputStream, ShellError> {
 
     Err(ShellError::labeled_error(
         "Error on exec",
-        format!("{}", err),
+        err.to_string(),
         &name,
     ))
 }