Run rustfmt on batches of multiple files

Author: Alexendoo

clippy_dev/src/fmt.rs

@@ -1,7 +1,7 @@
 use crate::clippy_project_root;
 use shell_escape::escape;
 use std::ffi::OsStr;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use std::process::{self, Command};
 use std::{fs, io};
 use walkdir::WalkDir;
@@ -56,6 +56,7 @@ pub fn run(check: bool, verbose: bool) {
         success &= cargo_fmt(context, &project_root.join("rustc_tools_util"))?;
         success &= cargo_fmt(context, &project_root.join("lintcheck"))?;
 
+        let mut paths = Vec::new();
         for entry in WalkDir::new(project_root.join("tests")) {
             let entry = entry?;
             let path = entry.path();
@@ -64,7 +65,11 @@ pub fn run(check: bool, verbose: bool) {
                 continue;
             }
 
-            success &= rustfmt(context, path)?;
+            paths.push(entry.into_path());
+        }
+
+        for chunk in paths.chunks(250) {
+            success &= rustfmt(context, chunk)?;
         }
 
         Ok(success)
@@ -185,14 +190,14 @@ fn rustfmt_test(context: &FmtContext) -> Result<(), CliError> {
     }
 }
 
-fn rustfmt(context: &FmtContext, path: &Path) -> Result<bool, CliError> {
-    let mut args = vec![path.as_os_str()];
+fn rustfmt(context: &FmtContext, paths: &[PathBuf]) -> Result<bool, CliError> {
+    let mut args = Vec::new();
     if context.check {
         args.push("--check".as_ref());
     }
+    args.extend(paths.iter().map(|path| path.as_os_str()));
+
     let success = exec(context, "rustfmt", std::env::current_dir()?, &args)?;
-    if !success {
-        eprintln!("rustfmt failed on {}", path.display());
-    }
+
     Ok(success)
 }