From a38ea96825ae9ea66812445c9a953aeb95403702 Mon Sep 17 00:00:00 2001
From: Ben Schulz <benshu@benshu.de>
Date: Fri, 18 Aug 2023 14:05:55 +0200
Subject: [PATCH] Remove Drop impl of mpsc Receiver and (Sync)Sender

---
 library/std/src/sync/mpsc/mod.rs                 | 15 ---------------
 tests/ui/span/send-is-not-static-std-sync.rs     |  2 +-
 tests/ui/span/send-is-not-static-std-sync.stderr |  8 +++-----
 3 files changed, 4 insertions(+), 21 deletions(-)

diff --git a/library/std/src/sync/mpsc/mod.rs b/library/std/src/sync/mpsc/mod.rs
index f92bb1a4b1f7d..d353c7bd5de9e 100644
--- a/library/std/src/sync/mpsc/mod.rs
+++ b/library/std/src/sync/mpsc/mod.rs
@@ -626,11 +626,6 @@ impl<T> Clone for Sender<T> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> Drop for Sender<T> {
-    fn drop(&mut self) {}
-}
-
 #[stable(feature = "mpsc_debug", since = "1.8.0")]
 impl<T> fmt::Debug for Sender<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -755,11 +750,6 @@ impl<T> Clone for SyncSender<T> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> Drop for SyncSender<T> {
-    fn drop(&mut self) {}
-}
-
 #[stable(feature = "mpsc_debug", since = "1.8.0")]
 impl<T> fmt::Debug for SyncSender<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
@@ -1096,11 +1086,6 @@ impl<T> IntoIterator for Receiver<T> {
     }
 }
 
-#[stable(feature = "rust1", since = "1.0.0")]
-impl<T> Drop for Receiver<T> {
-    fn drop(&mut self) {}
-}
-
 #[stable(feature = "mpsc_debug", since = "1.8.0")]
 impl<T> fmt::Debug for Receiver<T> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
diff --git a/tests/ui/span/send-is-not-static-std-sync.rs b/tests/ui/span/send-is-not-static-std-sync.rs
index f8ab5243c22af..9c1ee2871548e 100644
--- a/tests/ui/span/send-is-not-static-std-sync.rs
+++ b/tests/ui/span/send-is-not-static-std-sync.rs
@@ -46,7 +46,7 @@ fn channel() {
         tx.send(&z).unwrap();
     }
     //~^^ ERROR `z` does not live long enough
-    // (channels lack #[may_dangle], thus their dtors are implicit uses of `z`)
+    tx.use_ref(); // (channel drop glue does not use `z` => needs explicit use)
 }
 
 fn main() {}
diff --git a/tests/ui/span/send-is-not-static-std-sync.stderr b/tests/ui/span/send-is-not-static-std-sync.stderr
index eaba415adaa82..46534b39168cb 100644
--- a/tests/ui/span/send-is-not-static-std-sync.stderr
+++ b/tests/ui/span/send-is-not-static-std-sync.stderr
@@ -75,11 +75,9 @@ LL |         tx.send(&z).unwrap();
    |                 ^^ borrowed value does not live long enough
 LL |     }
    |     - `z` dropped here while still borrowed
-...
-LL | }
-   | - borrow might be used here, when `tx` is dropped and runs the `Drop` code for type `Sender`
-   |
-   = note: values in a scope are dropped in the opposite order they are defined
+LL |
+LL |     tx.use_ref(); // (channel drop glue does not use `z` => needs explicit use)
+   |     -- borrow later used here
 
 error: aborting due to 6 previous errors