Fix more clippy warnings;

clippy::comparison_to_empty
clippy::needless_question_mark
clippy::needless_borrow
clippy::match_like_matches_macro
clippy::vec_init_then_push
clippy::redundant_clone
clippy::nonminimal_bool
clippy::ptr_arg

Author: matthiaskrgr

src/cargo/core/compiler/build_context/target_info.rs

@@ -408,13 +408,7 @@ impl TargetInfo {
 
         let error = str::from_utf8(&output.stderr).unwrap();
         let output = str::from_utf8(&output.stdout).unwrap();
-        Ok(parse_crate_type(
-            crate_type,
-            &process,
-            output,
-            error,
-            &mut output.lines(),
-        )?)
+        parse_crate_type(crate_type, &process, output, error, &mut output.lines())
     }
 
     /// Returns all the file types generated by rustc for the given mode/target_kind.

src/cargo/core/compiler/build_plan.rs

@@ -7,7 +7,7 @@
 //! dependencies on other Invocations.
 
 use std::collections::BTreeMap;
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 
 use serde::Serialize;
 
@@ -63,10 +63,10 @@ impl Invocation {
         }
     }
 
-    pub fn add_output(&mut self, path: &PathBuf, link: &Option<PathBuf>) {
-        self.outputs.push(path.clone());
+    pub fn add_output(&mut self, path: &Path, link: &Option<PathBuf>) {
+        self.outputs.push(path.to_path_buf());
         if let Some(ref link) = *link {
-            self.links.insert(link.clone(), path.clone());
+            self.links.insert(link.clone(), path.to_path_buf());
         }
     }
 

src/cargo/core/compiler/fingerprint.rs

@@ -1432,9 +1432,9 @@ fn build_script_local_fingerprints(
 ) -> (
     Box<
         dyn FnOnce(
-            &BuildDeps,
-            Option<&dyn Fn() -> CargoResult<String>>,
-        ) -> CargoResult<Option<Vec<LocalFingerprint>>>
+                &BuildDeps,
+                Option<&dyn Fn() -> CargoResult<String>>,
+            ) -> CargoResult<Option<Vec<LocalFingerprint>>>
             + Send,
     >,
     bool,

src/cargo/core/compiler/job_queue.rs

@@ -915,7 +915,7 @@ impl<'cfg> DrainState<'cfg> {
                 // thread to run the job.
                 doit(JobState {
                     id,
-                    messages: messages.clone(),
+                    messages,
                     output: Some(cx.bcx.config),
                     rmeta_required: Cell::new(rmeta_required),
                     _marker: marker::PhantomData,

src/cargo/core/compiler/mod.rs

@@ -397,15 +397,11 @@ fn rustc(cx: &mut Context<'_, '_>, unit: &Unit, exec: &Arc<dyn Executor>) -> Car
         current_id: PackageId,
         metadata: Option<Metadata>,
     ) {
-        let metadata = match metadata {
-            Some(metadata) => metadata,
-            None => {
-                return;
-            }
-        };
-        if let Some(output) = build_script_outputs.get(current_id, metadata) {
-            for &(ref name, ref value) in output.env.iter() {
-                rustc.env(name, value);
+        if let Some(metadata) = metadata {
+            if let Some(output) = build_script_outputs.get(current_id, metadata) {
+                for &(ref name, ref value) in output.env.iter() {
+                    rustc.env(name, value);
+                }
             }
         }
     }
@@ -492,7 +488,7 @@ fn add_plugin_deps(
     rustc: &mut ProcessBuilder,
     build_script_outputs: &BuildScriptOutputs,
     build_scripts: &BuildScripts,
-    root_output: &PathBuf,
+    root_output: &Path,
 ) -> CargoResult<()> {
     let var = util::dylib_path_envvar();
     let search_path = rustc.get_env(var).unwrap_or_default();
@@ -516,7 +512,7 @@ fn add_plugin_deps(
 // Strip off prefixes like "native=" or "framework=" and filter out directories
 // **not** inside our output directory since they are likely spurious and can cause
 // clashes with system shared libraries (issue #3366).
-fn filter_dynamic_search_path<'a, I>(paths: I, root_output: &PathBuf) -> Vec<PathBuf>
+fn filter_dynamic_search_path<'a, I>(paths: I, root_output: &Path) -> Vec<PathBuf>
 where
     I: Iterator<Item = &'a PathBuf>,
 {

src/cargo/core/package.rs

@@ -607,9 +607,8 @@ impl<'a, 'cfg> Downloads<'a, 'cfg> {
     /// eventually be returned from `wait_for_download`. Returns `Some(pkg)` if
     /// the package is ready and doesn't need to be downloaded.
     pub fn start(&mut self, id: PackageId) -> CargoResult<Option<&'a Package>> {
-        Ok(self
-            .start_inner(id)
-            .chain_err(|| format!("failed to download `{}`", id))?)
+        self.start_inner(id)
+            .chain_err(|| format!("failed to download `{}`", id))
     }
 
     fn start_inner(&mut self, id: PackageId) -> CargoResult<Option<&'a Package>> {

src/cargo/core/profiles.rs

@@ -143,7 +143,7 @@ impl Profiles {
     fn add_root_profiles(
         profile_makers: &mut Profiles,
         profiles: &BTreeMap<InternedString, TomlProfile>,
-    )  {
+    ) {
         profile_makers.by_name.insert(
             InternedString::new("dev"),
             ProfileMaker::new(Profile::default_dev(), profiles.get("dev").cloned()),

src/cargo/ops/cargo_compile.rs

@@ -282,7 +282,7 @@ pub fn compile_ws<'a>(
     let bcx = create_bcx(ws, options, &interner)?;
     if options.build_config.unit_graph {
         unit_graph::emit_serialized_unit_graph(&bcx.roots, &bcx.unit_graph)?;
-        return Ok(Compilation::new(&bcx)?);
+        return Compilation::new(&bcx);
     }
 
     let _p = profile::start("compiling");

src/cargo/ops/cargo_output_metadata.rs

@@ -120,7 +120,7 @@ fn build_resolve_graph(
         metadata_opts.all_features,
         !metadata_opts.no_default_features,
     );
-    let resolve_opts = ResolveOpts::new(/*dev_deps*/ true, requested_features.clone());
+    let resolve_opts = ResolveOpts::new(/*dev_deps*/ true, requested_features);
     let force_all = if metadata_opts.filter_platforms.is_empty() {
         crate::core::resolver::features::ForceAllTargets::Yes
     } else {

src/cargo/ops/registry.rs

@@ -366,8 +366,8 @@ pub fn registry_configuration(
     // `registry.default` is handled in command-line parsing.
     let (index, token, process) = match registry {
         Some(registry) => {
-            validate_package_name(&registry, "registry name", "")?;
-            let index = Some(config.get_registry_index(&registry)?.to_string());
+            validate_package_name(registry, "registry name", "")?;
+            let index = Some(config.get_registry_index(registry)?.to_string());
             let token_key = format!("registries.{}.token", registry);
             let token = config.get_string(&token_key)?.map(|p| p.val);
             let process = if config.cli_unstable().credential_process {
@@ -471,7 +471,7 @@ fn registry(
     };
     let token = if validate_token {
         if index.is_some() {
-            if !token.is_some() {
+            if token.is_none() {
                 bail!("command-line argument --index requires --token to be specified");
             }
             token