Remove unnecessary `clone()`s in bootstrap

The performance difference is negligible, but it makes me feel better.

Note that this does not remove some clones in `config`, because it would
require changing the logic around (and performance doesn't matter
for bootstrap).

4 files changed, 39 insertions, 40 deletions

diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 34756af21e4..319f81c4ebb 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -1209,7 +1209,7 @@ impl<'a> Builder<'a> {
             cargo.env(format!("CC_{}", target.triple), &cc);
 
             let cflags = self.cflags(target, GitRepo::Rustc).join(" ");
-            cargo.env(format!("CFLAGS_{}", target.triple), cflags.clone());
+            cargo.env(format!("CFLAGS_{}", target.triple), &cflags);
 
             if let Some(ar) = self.ar(target) {
                 let ranlib = format!("{} s", ar.display());
diff --git a/src/bootstrap/config.rs b/src/bootstrap/config.rs
index 30c9e012cd6..7e2cb772186 100644
--- a/src/bootstrap/config.rs
+++ b/src/bootstrap/config.rs
@@ -500,6 +500,7 @@ impl Config {
 
     pub fn parse(args: &[String]) -> Config {
         let flags = Flags::parse(&args);
+
         let mut config = Config::default_opts();
         config.exclude = flags.exclude;
         config.rustc_error_format = flags.rustc_error_format;
@@ -551,14 +552,14 @@ impl Config {
         let has_targets = build.target.is_some() || flags.target.is_some();
         config.skip_only_host_steps = !has_hosts && has_targets;
 
-        config.hosts = if let Some(arg_host) = flags.host.clone() {
+        config.hosts = if let Some(arg_host) = flags.host {
             arg_host
         } else if let Some(file_host) = build.host {
             file_host.iter().map(|h| TargetSelection::from_user(h)).collect()
         } else {
             vec![config.build]
         };
-        config.targets = if let Some(arg_target) = flags.target.clone() {
+        config.targets = if let Some(arg_target) = flags.target {
             arg_target
         } else if let Some(file_target) = build.target {
             file_target.iter().map(|h| TargetSelection::from_user(h)).collect()
@@ -628,14 +629,14 @@ impl Config {
 
         config.verbose = cmp::max(config.verbose, flags.verbose);
 
-        if let Some(ref install) = toml.install {
-            config.prefix = install.prefix.clone().map(PathBuf::from);
-            config.sysconfdir = install.sysconfdir.clone().map(PathBuf::from);
-            config.datadir = install.datadir.clone().map(PathBuf::from);
-            config.docdir = install.docdir.clone().map(PathBuf::from);
-            set(&mut config.bindir, install.bindir.clone().map(PathBuf::from));
-            config.libdir = install.libdir.clone().map(PathBuf::from);
-            config.mandir = install.mandir.clone().map(PathBuf::from);
+        if let Some(install) = toml.install {
+            config.prefix = install.prefix.map(PathBuf::from);
+            config.sysconfdir = install.sysconfdir.map(PathBuf::from);
+            config.datadir = install.datadir.map(PathBuf::from);
+            config.docdir = install.docdir.map(PathBuf::from);
+            set(&mut config.bindir, install.bindir.map(PathBuf::from));
+            config.libdir = install.libdir.map(PathBuf::from);
+            config.mandir = install.mandir.map(PathBuf::from);
         }
 
         // We want the llvm-skip-rebuild flag to take precedence over the
@@ -658,7 +659,7 @@ impl Config {
         let mut optimize = None;
         let mut ignore_git = None;
 
-        if let Some(ref llvm) = toml.llvm {
+        if let Some(llvm) = toml.llvm {
             match llvm.ccache {
                 Some(StringOrBool::String(ref s)) => config.ccache = Some(s.to_string()),
                 Some(StringOrBool::Bool(true)) => {
@@ -726,7 +727,7 @@ impl Config {
             }
         }
 
-        if let Some(ref rust) = toml.rust {
+        if let Some(rust) = toml.rust {
             debug = rust.debug;
             debug_assertions = rust.debug_assertions;
             debug_assertions_std = rust.debug_assertions_std;
@@ -746,7 +747,7 @@ impl Config {
             set(&mut config.test_compare_mode, rust.test_compare_mode);
             set(&mut config.llvm_libunwind, rust.llvm_libunwind);
             set(&mut config.backtrace, rust.backtrace);
-            set(&mut config.channel, rust.channel.clone());
+            set(&mut config.channel, rust.channel);
             set(&mut config.rust_dist_src, rust.dist_src);
             set(&mut config.verbose_tests, rust.verbose_tests);
             // in the case "false" is set explicitly, do not overwrite the command line args
@@ -757,9 +758,9 @@ impl Config {
             set(&mut config.lld_enabled, rust.lld);
             set(&mut config.llvm_tools_enabled, rust.llvm_tools);
             config.rustc_parallel = rust.parallel_compiler.unwrap_or(false);
-            config.rustc_default_linker = rust.default_linker.clone();
-            config.musl_root = rust.musl_root.clone().map(PathBuf::from);
-            config.save_toolstates = rust.save_toolstates.clone().map(PathBuf::from);
+            config.rustc_default_linker = rust.default_linker;
+            config.musl_root = rust.musl_root.map(PathBuf::from);
+            config.save_toolstates = rust.save_toolstates.map(PathBuf::from);
             set(&mut config.deny_warnings, flags.deny_warnings.or(rust.deny_warnings));
             set(&mut config.backtrace_on_ice, rust.backtrace_on_ice);
             set(&mut config.rust_verify_llvm_ir, rust.verify_llvm_ir);
@@ -776,9 +777,9 @@ impl Config {
             config.rust_codegen_units_std = rust.codegen_units_std.map(threads_from_config);
         }
 
-        if let Some(ref t) = toml.target {
+        if let Some(t) = toml.target {
             for (triple, cfg) in t {
-                let mut target = Target::from_triple(triple);
+                let mut target = Target::from_triple(&triple);
 
                 if let Some(ref s) = cfg.llvm_config {
                     target.llvm_config = Some(config.src.join(s));
@@ -792,18 +793,18 @@ impl Config {
                 if let Some(s) = cfg.no_std {
                     target.no_std = s;
                 }
-                target.cc = cfg.cc.clone().map(PathBuf::from);
-                target.cxx = cfg.cxx.clone().map(PathBuf::from);
-                target.ar = cfg.ar.clone().map(PathBuf::from);
-                target.ranlib = cfg.ranlib.clone().map(PathBuf::from);
-                target.linker = cfg.linker.clone().map(PathBuf::from);
+                target.cc = cfg.cc.map(PathBuf::from);
+                target.cxx = cfg.cxx.map(PathBuf::from);
+                target.ar = cfg.ar.map(PathBuf::from);
+                target.ranlib = cfg.ranlib.map(PathBuf::from);
+                target.linker = cfg.linker.map(PathBuf::from);
                 target.crt_static = cfg.crt_static;
-                target.musl_root = cfg.musl_root.clone().map(PathBuf::from);
-                target.musl_libdir = cfg.musl_libdir.clone().map(PathBuf::from);
-                target.wasi_root = cfg.wasi_root.clone().map(PathBuf::from);
-                target.qemu_rootfs = cfg.qemu_rootfs.clone().map(PathBuf::from);
+                target.musl_root = cfg.musl_root.map(PathBuf::from);
+                target.musl_libdir = cfg.musl_libdir.map(PathBuf::from);
+                target.wasi_root = cfg.wasi_root.map(PathBuf::from);
+                target.qemu_rootfs = cfg.qemu_rootfs.map(PathBuf::from);
 
-                config.target_config.insert(TargetSelection::from_user(triple), target);
+                config.target_config.insert(TargetSelection::from_user(&triple), target);
             }
         }
 
@@ -821,10 +822,10 @@ impl Config {
             build_target.llvm_filecheck = Some(ci_llvm_bin.join(exe("FileCheck", config.build)));
         }
 
-        if let Some(ref t) = toml.dist {
-            config.dist_sign_folder = t.sign_folder.clone().map(PathBuf::from);
-            config.dist_gpg_password_file = t.gpg_password_file.clone().map(PathBuf::from);
-            config.dist_upload_addr = t.upload_addr.clone();
+        if let Some(t) = toml.dist {
+            config.dist_sign_folder = t.sign_folder.map(PathBuf::from);
+            config.dist_gpg_password_file = t.gpg_password_file.map(PathBuf::from);
+            config.dist_upload_addr = t.upload_addr;
             set(&mut config.rust_dist_src, t.src_tarball);
             set(&mut config.missing_tools, t.missing_tools);
         }
diff --git a/src/bootstrap/format.rs b/src/bootstrap/format.rs
index 6f93082e675..0ae9f9712d5 100644
--- a/src/bootstrap/format.rs
+++ b/src/bootstrap/format.rs
@@ -105,15 +105,13 @@ pub fn format(build: &Build, check: bool) {
         eprintln!("./x.py fmt is not supported on this channel");
         std::process::exit(1);
     });
-    let src = build.src.clone();
-    let walker = WalkBuilder::new(&build.src).types(matcher).overrides(ignore_fmt).build_parallel();
+    let src = &build.src;
+    let walker = WalkBuilder::new(src).types(matcher).overrides(ignore_fmt).build_parallel();
     walker.run(|| {
-        let src = src.clone();
-        let rustfmt_path = rustfmt_path.clone();
         Box::new(move |entry| {
             let entry = t!(entry);
             if entry.file_type().map_or(false, |t| t.is_file()) {
-                rustfmt(&src, &rustfmt_path, &entry.path(), check);
+                rustfmt(src, &rustfmt_path, &entry.path(), check);
             }
             ignore::WalkState::Continue
         })
diff --git a/src/bootstrap/sanity.rs b/src/bootstrap/sanity.rs
index 4d6612a376a..6826d177a4a 100644
--- a/src/bootstrap/sanity.rs
+++ b/src/bootstrap/sanity.rs
@@ -30,8 +30,8 @@ impl Finder {
         Self { cache: HashMap::new(), path: env::var_os("PATH").unwrap_or_default() }
     }
 
-    pub fn maybe_have<S: AsRef<OsStr>>(&mut self, cmd: S) -> Option<PathBuf> {
-        let cmd: OsString = cmd.as_ref().into();
+    pub fn maybe_have<S: Into<OsString>>(&mut self, cmd: S) -> Option<PathBuf> {
+        let cmd: OsString = cmd.into();
         let path = &self.path;
         self.cache
             .entry(cmd.clone())