From 8dc63758e2988cc1af948d2b2ee9347b854db59f Mon Sep 17 00:00:00 2001
From: Daniel Verkamp <dverkamp@chromium.org>
Date: Tue, 23 Aug 2022 16:37:43 -0700
Subject: [PATCH] cros_async, hypervisor: remove unnecessary unit-valued lets

The functions being called do not have return values (they return the
unit value), so the `let _ =` does nothing and can be removed.

Fixes a new clippy lint:
<https://rust-lang.github.io/rust-clippy/master/index.html#let_unit_value>

BUG=b:243677117
TEST=tools/clippy # with Rust 1.62

Change-Id: I6003b162c36e7be1ee71e3edc4e304c86fdc5676
Reviewed-on: https://chromium-review.googlesource.com/c/crosvm/crosvm/+/3854970
Tested-by: Daniel Verkamp <dverkamp@chromium.org>
Reviewed-by: Keiichi Watanabe <keiichiw@chromium.org>
Commit-Queue: Daniel Verkamp <dverkamp@chromium.org>
---
 cros_async/src/blocking/cancellable_pool.rs | 4 ++--
 cros_async/src/sys/unix/uring_executor.rs   | 2 +-
 hypervisor/src/kvm/mod.rs                   | 2 +-
 kvm/src/lib.rs                              | 2 +-
 4 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/cros_async/src/blocking/cancellable_pool.rs b/cros_async/src/blocking/cancellable_pool.rs
index 99fb333498..605862a3c8 100644
--- a/cros_async/src/blocking/cancellable_pool.rs
+++ b/cros_async/src/blocking/cancellable_pool.rs
@@ -392,7 +392,7 @@ mod test {
         let unfinished = pool.spawn(|| 5, || 0);
 
         // Disarming should cancel the task.
-        let _ = pool.disarm();
+        pool.disarm();
 
         // Shutdown the blocking thread. This will allow a worker to pick up the task that has
         // to be cancelled.
@@ -403,7 +403,7 @@ mod test {
         assert_eq!(block_on(unfinished), 0);
 
         // Now the pool is empty and can be shutdown without blocking.
-        let _ = pool.shutdown().unwrap();
+        pool.shutdown().unwrap();
     }
 
     #[test]
diff --git a/cros_async/src/sys/unix/uring_executor.rs b/cros_async/src/sys/unix/uring_executor.rs
index 4286aa3920..16355b409c 100644
--- a/cros_async/src/sys/unix/uring_executor.rs
+++ b/cros_async/src/sys/unix/uring_executor.rs
@@ -262,7 +262,7 @@ impl RegisteredSource {
 impl Drop for RegisteredSource {
     fn drop(&mut self) {
         if let Some(ex) = self.ex.upgrade() {
-            let _ = ex.deregister_source(self);
+            ex.deregister_source(self);
         }
     }
 }
diff --git a/hypervisor/src/kvm/mod.rs b/hypervisor/src/kvm/mod.rs
index 52155b93c2..cdcda8f2a3 100644
--- a/hypervisor/src/kvm/mod.rs
+++ b/hypervisor/src/kvm/mod.rs
@@ -1251,7 +1251,7 @@ impl BlockedSignal {
 
 impl Drop for BlockedSignal {
     fn drop(&mut self) {
-        let _ = unblock_signal(self.signal_num).expect("failed to restore signal mask");
+        unblock_signal(self.signal_num).expect("failed to restore signal mask");
     }
 }
 
diff --git a/kvm/src/lib.rs b/kvm/src/lib.rs
index fa93d544c5..a597c9214f 100644
--- a/kvm/src/lib.rs
+++ b/kvm/src/lib.rs
@@ -1757,7 +1757,7 @@ impl BlockedSignal {
 
 impl Drop for BlockedSignal {
     fn drop(&mut self) {
-        let _ = unblock_signal(self.signal_num).expect("failed to restore signal mask");
+        unblock_signal(self.signal_num).expect("failed to restore signal mask");
     }
 }