Auto merge of #7966 - Alexendoo:batch-rustfmt, r=camsteffen

Run rustfmt on batches of multiple files

changelog: none

This gives `cargo dev fmt` a nice speed boost, down from 90s (because old) on my laptop and 120s (because windows) on my desktop to ~5s on both

250 at a time was to give windows a good amount of headroom (failed at ~800, https://github.com/rust-lang/rust/issues/40384)

Also adds rustfmt to the toolchain file and has the clippy_dev workflow test using the pinned version as a follow up to #7963

3 files changed, 25 insertions, 29 deletions

diff --git a/.github/workflows/clippy_dev.yml b/.github/workflows/clippy_dev.yml
index 9a5416153ab..fe8bce00fa8 100644
--- a/.github/workflows/clippy_dev.yml
+++ b/.github/workflows/clippy_dev.yml
@@ -25,18 +25,6 @@ jobs:
     - name: Checkout
       uses: actions/checkout@v2.3.3
 
-    - name: remove toolchain file
-      run: rm rust-toolchain
-
-    - name: rust-toolchain
-      uses: actions-rs/toolchain@v1.0.6
-      with:
-        toolchain: nightly
-        target: x86_64-unknown-linux-gnu
-        profile: minimal
-        components: rustfmt
-        default: true
-
     # Run
     - name: Build
       run: cargo build --features deny-warnings
diff --git a/clippy_dev/src/fmt.rs b/clippy_dev/src/fmt.rs
index bdca75e609f..9ceadee58ea 100644
--- a/clippy_dev/src/fmt.rs
+++ b/clippy_dev/src/fmt.rs
@@ -1,6 +1,7 @@
 use crate::clippy_project_root;
+use itertools::Itertools;
 use shell_escape::escape;
-use std::ffi::OsStr;
+use std::ffi::{OsStr, OsString};
 use std::path::Path;
 use std::process::{self, Command};
 use std::{fs, io};
@@ -56,15 +57,22 @@ 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"))?;
 
-        for entry in WalkDir::new(project_root.join("tests")) {
-            let entry = entry?;
-            let path = entry.path();
-
-            if path.extension() != Some("rs".as_ref()) || entry.file_name() == "ice-3891.rs" {
-                continue;
-            }
-
-            success &= rustfmt(context, path)?;
+        let chunks = WalkDir::new(project_root.join("tests"))
+            .into_iter()
+            .filter_map(|entry| {
+                let entry = entry.expect("failed to find tests");
+                let path = entry.path();
+
+                if path.extension() != Some("rs".as_ref()) || entry.file_name() == "ice-3891.rs" {
+                    None
+                } else {
+                    Some(entry.into_path().into_os_string())
+                }
+            })
+            .chunks(250);
+
+        for chunk in &chunks {
+            success &= rustfmt(context, chunk)?;
         }
 
         Ok(success)
@@ -185,14 +193,14 @@ 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: impl Iterator<Item = OsString>) -> Result<bool, CliError> {
+    let mut args = Vec::new();
     if context.check {
-        args.push("--check".as_ref());
+        args.push(OsString::from("--check"));
     }
+    args.extend(paths);
+
     let success = exec(context, "rustfmt", std::env::current_dir()?, &args)?;
-    if !success {
-        eprintln!("rustfmt failed on {}", path.display());
-    }
+
     Ok(success)
 }
diff --git a/rust-toolchain b/rust-toolchain
index 09554c08987..31e2aecad2c 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1,3 +1,3 @@
 [toolchain]
 channel = "nightly-2021-11-04"
-components = ["llvm-tools-preview", "rustc-dev", "rust-src"]
+components = ["llvm-tools-preview", "rustc-dev", "rust-src", "rustfmt"]