Auto merge of #130803 - cuviper:file-buffered, r=joshtriplett

Add `File` constructors that return files wrapped with a buffer

In addition to the light convenience, these are intended to raise visibility that buffering is something you should consider when opening a file, since unbuffered I/O is a common performance footgun to Rust newcomers.

ACP: https://github.com/rust-lang/libs-team/issues/446
Tracking Issue: #130804

2 files changed, 3 insertions, 3 deletions

diff --git a/compiler/rustc_monomorphize/src/lib.rs b/compiler/rustc_monomorphize/src/lib.rs
index 91101ddd590..e92e6978d0f 100644
--- a/compiler/rustc_monomorphize/src/lib.rs
+++ b/compiler/rustc_monomorphize/src/lib.rs
@@ -1,5 +1,6 @@
 // tidy-alphabetical-start
 #![feature(array_windows)]
+#![feature(file_buffered)]
 #![feature(if_let_guard)]
 #![feature(let_chains)]
 #![warn(unreachable_pub)]
diff --git a/compiler/rustc_monomorphize/src/partitioning.rs b/compiler/rustc_monomorphize/src/partitioning.rs
index 1c1e6164f2e..ad05cca66ca 100644
--- a/compiler/rustc_monomorphize/src/partitioning.rs
+++ b/compiler/rustc_monomorphize/src/partitioning.rs
@@ -95,7 +95,7 @@
 use std::cmp;
 use std::collections::hash_map::Entry;
 use std::fs::{self, File};
-use std::io::{BufWriter, Write};
+use std::io::Write;
 use std::path::{Path, PathBuf};
 
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
@@ -1243,8 +1243,7 @@ fn dump_mono_items_stats<'tcx>(
     let ext = format.extension();
     let filename = format!("{crate_name}.mono_items.{ext}");
     let output_path = output_directory.join(&filename);
-    let file = File::create(&output_path)?;
-    let mut file = BufWriter::new(file);
+    let mut file = File::create_buffered(&output_path)?;
 
     // Gather instantiated mono items grouped by def_id
     let mut items_per_def_id: FxIndexMap<_, Vec<_>> = Default::default();