1 files changed, 13 insertions, 21 deletions

diff --git a/src/librustc_codegen_utils/codegen_backend.rs b/src/librustc_codegen_utils/codegen_backend.rs
index 046f0cccfee..74718460f56 100644
--- a/src/librustc_codegen_utils/codegen_backend.rs
+++ b/src/librustc_codegen_utils/codegen_backend.rs
@@ -22,8 +22,8 @@
 #![feature(box_syntax)]
 
 use std::any::Any;
-use std::io::{self, Write};
-use std::fs::File;
+use std::io::Write;
+use std::fs;
 use std::path::Path;
 use std::sync::{mpsc, Arc};
 
@@ -81,13 +81,9 @@ pub struct NoLlvmMetadataLoader;
 
 impl MetadataLoader for NoLlvmMetadataLoader {
     fn get_rlib_metadata(&self, _: &Target, filename: &Path) -> Result<MetadataRef, String> {
-        let mut file = File::open(filename)
-            .map_err(|e| format!("metadata file open err: {:?}", e))?;
-
-        let mut buf = Vec::new();
-        io::copy(&mut file, &mut buf).unwrap();
-        let buf: OwningRef<Vec<u8>, [u8]> = OwningRef::new(buf).into();
-        return Ok(rustc_erase_owner!(buf.map_owner_box()));
+        let buf = fs::read(filename).map_err(|e| format!("metadata file open err: {:?}", e))?;
+        let buf: OwningRef<Vec<u8>, [u8]> = OwningRef::new(buf);
+        Ok(rustc_erase_owner!(buf.map_owner_box()))
     }
 
     fn get_dylib_metadata(&self, target: &Target, filename: &Path) -> Result<MetadataRef, String> {
@@ -103,7 +99,7 @@ pub struct OngoingCodegen {
 }
 
 impl MetadataOnlyCodegenBackend {
-    pub fn new() -> Box<dyn CodegenBackend> {
+    pub fn boxed() -> Box<dyn CodegenBackend> {
         box MetadataOnlyCodegenBackend(())
     }
 }
@@ -165,15 +161,12 @@ impl CodegenBackend for MetadataOnlyCodegenBackend {
                 tcx,
                 collector::MonoItemCollectionMode::Eager
             ).0 {
-            match mono_item {
-                MonoItem::Fn(inst) => {
-                    let def_id = inst.def_id();
-                    if def_id.is_local()  {
-                        let _ = inst.def.is_inline(tcx);
-                        let _ = tcx.codegen_fn_attrs(def_id);
-                    }
+            if let MonoItem::Fn(inst) = mono_item {
+                let def_id = inst.def_id();
+                if def_id.is_local()  {
+                    let _ = inst.def.is_inline(tcx);
+                    let _ = tcx.codegen_fn_attrs(def_id);
                 }
-                _ => {}
             }
         }
         tcx.sess.abort_if_errors();
@@ -181,7 +174,7 @@ impl CodegenBackend for MetadataOnlyCodegenBackend {
         let metadata = tcx.encode_metadata();
 
         box OngoingCodegen {
-            metadata: metadata,
+            metadata,
             metadata_version: tcx.metadata_encoding_version().to_vec(),
             crate_name: tcx.crate_name(LOCAL_CRATE),
         }
@@ -212,8 +205,7 @@ impl CodegenBackend for MetadataOnlyCodegenBackend {
             } else {
                 &ongoing_codegen.metadata.raw_data
             };
-            let mut file = File::create(&output_name).unwrap();
-            file.write_all(metadata).unwrap();
+            fs::write(&output_name, metadata).unwrap();
         }
 
         sess.abort_if_errors();