Avoid ref when using format! in compiler

Clean up a few minor refs in `format!` macro, as it has a performance cost. Apparently the compiler is unable to inline `format!("{}", &variable)`, and does a run-time double-reference instead (format macro already does one level referencing). Inlining format args prevents accidental `&` misuse.
rust-lang · bors · Jul 20, 2024 · Jul 10, 2024 · Jul 13, 2024 · Jul 15, 2024
commit 8bcf0b4a374116c5f9cba9b02deb19b3ea694380
diff --git a/src/bootstrap/src/core/build_steps/compile.rs b/src/bootstrap/src/core/build_steps/compile.rs
@@ -695,7 +695,7 @@ fn copy_sanitizers(
             || target == "x86_64-apple-ios"
         {
             // Update the library’s install name to reflect that it has been renamed.
-            apple_darwin_update_library_name(builder, &dst, &format!("@rpath/{}", &runtime.name));
+            apple_darwin_update_library_name(builder, &dst, &format!("@rpath/{}", runtime.name));
             // Upon renaming the install name, the code signature of the file will invalidate,
             // so we will sign it again.
             apple_darwin_sign_file(builder, &dst);

diff --git a/src/bootstrap/src/core/build_steps/llvm.rs b/src/bootstrap/src/core/build_steps/llvm.rs
@@ -1411,7 +1411,7 @@ impl Step for Libunwind {
                 }
             }
         }
-        assert_eq!(cpp_len, count, "Can't get object files from {:?}", &out_dir);
+        assert_eq!(cpp_len, count, "Can't get object files from {out_dir:?}");
 
         cc_cfg.compile("unwind");
         out_dir

diff --git a/src/bootstrap/src/utils/cc_detect.rs b/src/bootstrap/src/utils/cc_detect.rs
@@ -142,15 +142,15 @@ pub fn find_target(build: &Build, target: TargetSelection) {
         build.cxx.borrow_mut().insert(target, compiler);
     }
 
-    build.verbose(|| println!("CC_{} = {:?}", &target.triple, build.cc(target)));
-    build.verbose(|| println!("CFLAGS_{} = {:?}", &target.triple, cflags));
+    build.verbose(|| println!("CC_{} = {:?}", target.triple, build.cc(target)));
+    build.verbose(|| println!("CFLAGS_{} = {cflags:?}", target.triple));
     if let Ok(cxx) = build.cxx(target) {
         let cxxflags = build.cflags(target, GitRepo::Rustc, CLang::Cxx);
-        build.verbose(|| println!("CXX_{} = {:?}", &target.triple, cxx));
-        build.verbose(|| println!("CXXFLAGS_{} = {:?}", &target.triple, cxxflags));
+        build.verbose(|| println!("CXX_{} = {cxx:?}", target.triple));
+        build.verbose(|| println!("CXXFLAGS_{} = {cxxflags:?}", target.triple));
     }
     if let Some(ar) = ar {
-        build.verbose(|| println!("AR_{} = {:?}", &target.triple, ar));
+        build.verbose(|| println!("AR_{} = {ar:?}", target.triple));
         build.ar.borrow_mut().insert(target, ar);
     }
 

diff --git a/src/bootstrap/src/utils/tarball.rs b/src/bootstrap/src/utils/tarball.rs
@@ -244,7 +244,7 @@ impl<'a> Tarball<'a> {
             cmd.arg("generate")
                 .arg("--image-dir")
                 .arg(&this.image_dir)
-                .arg(format!("--component-name={}", &component_name));
+                .arg(format!("--component-name={component_name}"));
 
             if let Some((dir, dirs)) = this.bulk_dirs.split_first() {
                 let mut arg = dir.as_os_str().to_os_string();

diff --git a/src/librustdoc/html/format.rs b/src/librustdoc/html/format.rs
@@ -850,7 +850,7 @@ fn resolved_path<'cx>(
         }
     }
     if w.alternate() {
-        write!(w, "{}{:#}", &last.name, last.args.print(cx))?;
+        write!(w, "{}{:#}", last.name, last.args.print(cx))?;
     } else {
         let path = if use_absolute {
             if let Ok((_, _, fqp)) = href(did, cx) {
-Original file line number
+Diff line change
@@ Expand Up / @@ -1411,7 +1411,7 @@ impl Step for Libunwind { @@
                     }
                 }
             }
-            assert_eq!(cpp_len, count, "Can't get object files from {:?}", &out_dir);
+            assert_eq!(cpp_len, count, "Can't get object files from {out_dir:?}");
             cc_cfg.compile("unwind");
             out_dir
@@ Expand Down @@