Auto merge of #12160 - epage:nightly, r=weihanglo

fix: Pass CI on nightly

It appears rustc is now giving warnings when calling `drop` on `Copy` types (`drop-copy`)

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

@@ -812,7 +812,7 @@ impl<'cfg> DrainState<'cfg> {
  );
  if !cx.bcx.build_config.build_plan {
  // It doesn't really matter if this fails.
- drop(cx.bcx.config.shell().status("Finished", message));
+ let _ = cx.bcx.config.shell().status("Finished", message);
  future_incompat::save_and_display_report(
  cx.bcx,
  &self.per_package_future_incompat_reports,
@@ -836,7 +836,7 @@ impl<'cfg> DrainState<'cfg> {
  if new_err.print_always || err_state.count == 0 {
  crate::display_error(&new_err.error, shell);
  if err_state.count == 0 && !self.active.is_empty() {
- drop(shell.warn("build failed, waiting for other jobs to finish..."));
+ let _ = shell.warn("build failed, waiting for other jobs to finish...");
  }
  err_state.count += 1;
  } else {
@@ -863,11 +863,11 @@ impl<'cfg> DrainState<'cfg> {
  .values()
  .map(|u| self.name_for_progress(u))
  .collect::<Vec<_>>();
- drop(self.progress.tick_now(
+ let _ = self.progress.tick_now(
  self.finished,
  self.total_units,
  &format!(": {}", active_names.join(", ")),
- ));
+ );
  }
 
  fn name_for_progress(&self, unit: &Unit) -> String {
@@ -1005,12 +1005,16 @@ impl<'cfg> DrainState<'cfg> {
  message.push_str(" generated ");
  match count.total {
  1 => message.push_str("1 warning"),
- n => drop(write!(message, "{} warnings", n)),
+ n => {
+ let _ = write!(message, "{} warnings", n);
+ }
  };
  match count.duplicates {
  0 => {}
  1 => message.push_str(" (1 duplicate)"),
- n => drop(write!(message, " ({} duplicates)", n)),
+ n => {
+ let _ = write!(message, " ({} duplicates)", n);
+ }
  }
  // Only show the `cargo fix` message if its a local `Unit`
  if unit.is_local() {
@@ -1054,7 +1058,7 @@ impl<'cfg> DrainState<'cfg> {
  }
  // Errors are ignored here because it is tricky to handle them
  // correctly, and they aren't important.
- drop(config.shell().warn(message));
+ let _ = config.shell().warn(message);
  }
 
  fn finish(