Auto merge of #8189 - matthiaskrgr:clippy_v12, r=ehuss

clippy fixes

Author: bors

crates/cargo-test-support/src/registry.rs

@@ -442,7 +442,7 @@ impl Package {
         } else {
             registry_path.join(&file)
         };
-        let prev = fs::read_to_string(&dst).unwrap_or(String::new());
+        let prev = fs::read_to_string(&dst).unwrap_or_default();
         t!(fs::create_dir_all(dst.parent().unwrap()));
         t!(fs::write(&dst, prev + &line[..] + "\n"));
 

src/bin/cargo/commands/tree.rs

@@ -206,7 +206,7 @@ fn parse_edge_kinds(config: &Config, args: &ArgMatches<'_>) -> CargoResult<HashS
             .warn("the --no-dev-dependencies flag has changed to -e=no-dev")?;
         kinds.push("no-dev");
     }
-    if kinds.len() == 0 {
+    if kinds.is_empty() {
         kinds.extend(&["normal", "build", "dev"]);
     }
 

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

@@ -448,7 +448,7 @@ fn env_args(
     // This means that, e.g., even if the specified --target is the
     // same as the host, build scripts in plugins won't get
     // RUSTFLAGS.
-    if requested_kinds != &[CompileKind::Host] && kind.is_host() {
+    if requested_kinds != [CompileKind::Host] && kind.is_host() {
         // This is probably a build script or plugin and we're
         // compiling with --target. In this scenario there are
         // no rustflags we can apply.

src/cargo/core/compiler/compile_kind.rs

@@ -55,7 +55,7 @@ impl CompileKind {
         if targets.len() > 1 && !config.cli_unstable().multitarget {
             bail!("specifying multiple `--target` flags requires `-Zmultitarget`")
         }
-        if targets.len() != 0 {
+        if !targets.is_empty() {
             return Ok(targets
                 .iter()
                 .map(|value| Ok(CompileKind::Target(CompileTarget::new(value)?)))

src/cargo/core/compiler/standard_lib.rs

@@ -161,7 +161,7 @@ pub fn generate_std_roots(
         let features = std_features.activated_features(pkg.package_id(), FeaturesFor::NormalOrDev);
 
         for kind in kinds {
-            let list = ret.entry(*kind).or_insert(Vec::new());
+            let list = ret.entry(*kind).or_insert_with(Vec::new);
             list.push(interner.intern(
                 pkg,
                 lib,
@@ -173,7 +173,7 @@ pub fn generate_std_roots(
             ));
         }
     }
-    return Ok(ret);
+    Ok(ret)
 }
 
 fn detect_sysroot_src_path(target_data: &RustcTargetData) -> CargoResult<PathBuf> {

src/cargo/core/compiler/unit.rs

@@ -204,6 +204,6 @@ impl UnitInterner {
         }
         let item = Rc::new(item.clone());
         me.cache.insert(item.clone());
-        return item;
+        item
     }
 }

src/cargo/core/compiler/unit_graph.rs

@@ -113,6 +113,6 @@ pub fn emit_serialized_unit_graph(root_units: &[Unit], unit_graph: &UnitGraph) -
     let stdout = std::io::stdout();
     let mut lock = stdout.lock();
     serde_json::to_writer(&mut lock, &s)?;
-    write!(lock, "\n")?;
+    writeln!(lock)?;
     Ok(())
 }

src/cargo/core/manifest.rs

@@ -669,7 +669,7 @@ impl Target {
             .set_name(name)
             .set_doctest(true)
             .set_doc(true);
-        return target;
+        target
     }
 
     pub fn bin_target(
@@ -684,7 +684,7 @@ impl Target {
             .set_name(name)
             .set_required_features(required_features)
             .set_doc(true);
-        return target;
+        target
     }
 
     /// Builds a `Target` corresponding to the `build = "build.rs"` entry.
@@ -696,7 +696,7 @@ impl Target {
             .set_for_host(true)
             .set_benched(false)
             .set_tested(false);
-        return target;
+        target
     }
 
     pub fn metabuild_target(name: &str) -> Target {
@@ -707,7 +707,7 @@ impl Target {
             .set_for_host(true)
             .set_benched(false)
             .set_tested(false);
-        return target;
+        target
     }
 
     pub fn example_target(
@@ -733,7 +733,7 @@ impl Target {
             .set_required_features(required_features)
             .set_tested(false)
             .set_benched(false);
-        return target;
+        target
     }
 
     pub fn test_target(
@@ -748,7 +748,7 @@ impl Target {
             .set_name(name)
             .set_required_features(required_features)
             .set_benched(false);
-        return target;
+        target
     }
 
     pub fn bench_target(
@@ -763,7 +763,7 @@ impl Target {
             .set_name(name)
             .set_required_features(required_features)
             .set_tested(false);
-        return target;
+        target
     }
 
     pub fn name(&self) -> &str {

src/cargo/core/registry.rs

@@ -622,7 +622,7 @@ fn lock(
 
     // Lock the summary's ID if possible
     let summary = match pair {
-        Some((precise, _)) => summary.override_id(precise.clone()),
+        Some((precise, _)) => summary.override_id(*precise),
         None => summary,
     };
     summary.map_dependencies(|dep| {

src/cargo/core/resolver/conflict_cache.rs

@@ -213,7 +213,7 @@ impl ConflictCache {
 
         for c in con.keys() {
             self.dep_from_pid
-                .entry(c.clone())
+                .entry(*c)
                 .or_insert_with(HashSet::new)
                 .insert(dep.clone());
         }