diff --git a/src/cargo/core/compiler/mod.rs b/src/cargo/core/compiler/mod.rs
index 2781ffbd8cf..884f1efc367 100644
--- a/src/cargo/core/compiler/mod.rs
+++ b/src/cargo/core/compiler/mod.rs
@@ -648,7 +648,7 @@ fn rustdoc(cx: &mut Context<'_, '_>, unit: &Unit) -> CargoResult<Work> {
         rustdoc.args(args);
     }
 
-    let metadata = cx.metadata_for_doc_units[&unit];
+    let metadata = cx.metadata_for_doc_units[unit];
     rustdoc.arg("-C").arg(format!("metadata={}", metadata));
 
     let scrape_output_path = |unit: &Unit| -> CargoResult<PathBuf> {
diff --git a/src/cargo/core/compiler/unit_dependencies.rs b/src/cargo/core/compiler/unit_dependencies.rs
index ae8ca69aa46..d89d416b1a6 100644
--- a/src/cargo/core/compiler/unit_dependencies.rs
+++ b/src/cargo/core/compiler/unit_dependencies.rs
@@ -132,7 +132,7 @@ fn calc_deps_of_std(
     // Compute dependencies for the standard library.
     state.is_std = true;
     for roots in std_roots.values() {
-        deps_of_roots(roots, &mut state)?;
+        deps_of_roots(roots, state)?;
     }
     state.is_std = false;
     Ok(Some(std::mem::take(&mut state.unit_dependencies)))
@@ -172,7 +172,7 @@ fn attach_std_deps(
 
 /// Compute all the dependencies of the given root units.
 /// The result is stored in state.unit_dependencies.
-fn deps_of_roots(roots: &[Unit], mut state: &mut State<'_, '_>) -> CargoResult<()> {
+fn deps_of_roots(roots: &[Unit], state: &mut State<'_, '_>) -> CargoResult<()> {
     for unit in roots.iter() {
         // Dependencies of tests/benches should not have `panic` set.
         // We check the global test mode to see if we are running in `cargo
@@ -200,7 +200,7 @@ fn deps_of_roots(roots: &[Unit], mut state: &mut State<'_, '_>) -> CargoResult<(
         } else {
             UnitFor::new_normal()
         };
-        deps_of(unit, &mut state, unit_for)?;
+        deps_of(unit, state, unit_for)?;
     }
 
     Ok(())
diff --git a/src/cargo/util/toml/mod.rs b/src/cargo/util/toml/mod.rs
index aa26d0897e8..e34b0809330 100644
--- a/src/cargo/util/toml/mod.rs
+++ b/src/cargo/util/toml/mod.rs
@@ -1248,7 +1248,7 @@ impl TomlManifest {
             for (name, platform) in me.target.iter().flatten() {
                 cx.platform = {
                     let platform: Platform = name.parse()?;
-                    platform.check_cfg_attributes(&mut cx.warnings);
+                    platform.check_cfg_attributes(cx.warnings);
                     Some(platform)
                 };
                 process_dependencies(&mut cx, platform.dependencies.as_ref(), None)?;