refactor(compile): Be consistent in unused_externs type

src/cargo/core/compiler/job_queue/job_state.rs

@@ -9,6 +9,7 @@ use crate::core::compiler::locking::LockKey;
 use crate::core::compiler::timings::SectionTiming;
 use crate::util::Queue;
 use crate::util::context::WarningHandling;
+use crate::util::interning::InternedString;
 use crate::{CargoResult, core::compiler::locking::LockManager};
 
 use super::{Artifact, DiagDedupe, Job, JobId, Message};
@@ -224,7 +225,7 @@ impl<'a, 'gctx> JobState<'a, 'gctx> {
     ///
     /// This is useful for checking unused dependencies.
     /// Should only be called once, as the compiler only emits it once per compilation.
-    pub fn unused_externs(&self, unused_externs: Vec<String>) {
+    pub fn unused_externs(&self, unused_externs: Vec<InternedString>) {
         self.messages
             .push(Message::UnusedExterns(self.id, unused_externs));
     }

src/cargo/core/compiler/job_queue/mod.rs

@@ -149,6 +149,7 @@ use crate::util::CargoResult;
 use crate::util::context::WarningHandling;
 use crate::util::diagnostic_server::{self, DiagnosticPrinter};
 use crate::util::errors::AlreadyPrintedError;
+use crate::util::interning::InternedString;
 use crate::util::machine_message::{self, Message as _};
 use crate::util::{self, internal};
 use crate::util::{DependencyQueue, GlobalContext, Progress, ProgressStyle, Queue};
@@ -387,7 +388,7 @@ enum Message {
     Finish(JobId, Artifact, CargoResult<()>),
     FutureIncompatReport(JobId, Vec<FutureBreakageItem>),
     SectionTiming(JobId, SectionTiming),
-    UnusedExterns(JobId, Vec<String>),
+    UnusedExterns(JobId, Vec<InternedString>),
 }
 
 impl<'gctx> JobQueue<'gctx> {

src/cargo/core/compiler/mod.rs

@@ -2399,7 +2399,7 @@ fn on_stderr_line_inner(
 
     #[derive(serde::Deserialize)]
     struct UnusedExterns {
-        unused_extern_names: Vec<String>,
+        unused_extern_names: Vec<InternedString>,
     }
     if let Ok(uext) = serde_json::from_str::<UnusedExterns>(compiler_message.get()) {
         trace!(

src/cargo/core/compiler/unused_deps.rs

@@ -111,7 +111,11 @@ impl UnusedDepState {
         Self { states }
     }
 
-    pub fn record_unused_externs_for_unit(&mut self, unit: &Unit, unused_externs: Vec<String>) {
+    pub fn record_unused_externs_for_unit(
+        &mut self,
+        unit: &Unit,
+        unused_externs: Vec<InternedString>,
+    ) {
         let pkg_id = unit.pkg.package_id();
         let dep_kind = dep_kind_of(unit);
         trace!(
@@ -129,7 +133,7 @@ impl UnusedDepState {
             .unused_externs
             .entry(unit.clone())
             .or_default()
-            .extend(unused_externs.into_iter().map(|s| InternedString::new(&s)));
+            .extend(unused_externs);
     }
 
     #[instrument(skip_all)]