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.

Author: nyurik

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(&dst, &format!("@rpath/{}", &runtime.name));
+            apple_darwin_update_library_name(&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(&dst);

src/bootstrap/src/core/build_steps/llvm.rs

@@ -1410,7 +1410,7 @@ 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

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);
     }
 

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();

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) {

src/tools/clippy/clippy_lints/src/approx_const.rs

@@ -95,7 +95,7 @@ impl ApproxConstant {
                         cx,
                         APPROX_CONSTANT,
                         e.span,
-                        format!("approximate value of `{module}::consts::{}` found", &name),
+                        format!("approximate value of `{module}::consts::{name}` found"),
                         None,
                         "consider using the constant directly",
                     );

src/tools/clippy/clippy_lints/src/default.rs

@@ -221,7 +221,7 @@ impl<'tcx> LateLintPass<'tcx> for Default {
                         .map(ToString::to_string)
                         .collect::<Vec<_>>()
                         .join(", ");
-                    format!("{adt_def_ty_name}::<{}>", &tys_str)
+                    format!("{adt_def_ty_name}::<{tys_str}>")
                 } else {
                     binding_type.to_string()
                 };

src/tools/clippy/clippy_lints/src/methods/open_options.rs

@@ -151,7 +151,7 @@ fn check_open_options(cx: &LateContext<'_>, settings: &[(OpenOption, Argument, S
                 cx,
                 NONSENSICAL_OPEN_OPTIONS,
                 prev_span,
-                format!("the method `{}` is called more than once", &option),
+                format!("the method `{option}` is called more than once"),
             );
         }
     }

src/tools/clippy/clippy_lints/src/methods/wrong_self_convention.rs

@@ -127,9 +127,9 @@ pub(super) fn check<'tcx>(
                         .collect::<Vec<_>>()
                         .join(" and ");
 
-                    format!("methods with the following characteristics: ({})", &s)
+                    format!("methods with the following characteristics: ({s})")
                 } else {
-                    format!("methods called {}", &conventions[0])
+                    format!("methods called {}", conventions[0])
                 }
             };
 

src/tools/clippy/clippy_lints/src/no_effect.rs

@@ -272,7 +272,7 @@ fn check_unnecessary_operation(cx: &LateContext<'_>, stmt: &Stmt<'_>) {
             }
             let snippet =
                 if let (Some(arr), Some(func)) = (snippet_opt(cx, reduced[0].span), snippet_opt(cx, reduced[1].span)) {
-                    format!("assert!({}.len() > {});", &arr, &func)
+                    format!("assert!({arr}.len() > {func});")
                 } else {
                     return;
                 };