From 0f9c349834622fa337c8dab886af4041bcdad5bb Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Mon, 27 Sep 2021 08:43:30 -0700
Subject: [PATCH 1/3] lock types
---
library/std/src/lib.rs | 1 +
library/std/src/sync/mutex.rs | 6 +++++
library/std/src/sync/rwlock.rs | 12 +++++++++
src/test/ui/lint/must_not_suspend/mutex.rs | 13 ++++++++++
.../ui/lint/must_not_suspend/mutex.stderr | 26 +++++++++++++++++++
5 files changed, 58 insertions(+)
create mode 100644 src/test/ui/lint/must_not_suspend/mutex.rs
create mode 100644 src/test/ui/lint/must_not_suspend/mutex.stderr
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index f69baba9e733f..9d150b69f6a6d 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -297,6 +297,7 @@
#![feature(maybe_uninit_slice)]
#![feature(maybe_uninit_uninit_array)]
#![feature(min_specialization)]
+#![cfg_attr(not(bootstrap), feature(must_not_suspend))]
#![feature(needs_panic_runtime)]
#![feature(negative_impls)]
#![feature(never_type)]
diff --git a/library/std/src/sync/mutex.rs b/library/std/src/sync/mutex.rs
index e1d6324c17e33..9abd4b547c77e 100644
--- a/library/std/src/sync/mutex.rs
+++ b/library/std/src/sync/mutex.rs
@@ -188,6 +188,12 @@ unsafe impl<T: ?Sized + Send> Sync for Mutex<T> {}
/// [`lock`]: Mutex::lock
/// [`try_lock`]: Mutex::try_lock
#[must_use = "if unused the Mutex will immediately unlock"]
+#[cfg_attr(
+ not(bootstrap),
+ must_not_suspend = "Holding a MutexGuard across suspend \
+ points can cause deadlocks, delays, \
+ and cause Future's to not implement `Send`"
+)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct MutexGuard<'a, T: ?Sized + 'a> {
lock: &'a Mutex<T>,
diff --git a/library/std/src/sync/rwlock.rs b/library/std/src/sync/rwlock.rs
index e50d62d817376..1523d36323fd9 100644
--- a/library/std/src/sync/rwlock.rs
+++ b/library/std/src/sync/rwlock.rs
@@ -95,6 +95,12 @@ unsafe impl<T: ?Sized + Send + Sync> Sync for RwLock<T> {}
/// [`read`]: RwLock::read
/// [`try_read`]: RwLock::try_read
#[must_use = "if unused the RwLock will immediately unlock"]
+#[cfg_attr(
+ not(bootstrap),
+ must_not_suspend = "Holding a RwLockReadGuard across suspend \
+ points can cause deadlocks, delays, \
+ and cause Future's to not implement `Send`"
+)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RwLockReadGuard<'a, T: ?Sized + 'a> {
lock: &'a RwLock<T>,
@@ -115,6 +121,12 @@ unsafe impl<T: ?Sized + Sync> Sync for RwLockReadGuard<'_, T> {}
/// [`write`]: RwLock::write
/// [`try_write`]: RwLock::try_write
#[must_use = "if unused the RwLock will immediately unlock"]
+#[cfg_attr(
+ not(bootstrap),
+ must_not_suspend = "Holding a RwLockWriteGuard across suspend \
+ points can cause deadlocks, delays, \
+ and cause Future's to not implement `Send`"
+)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RwLockWriteGuard<'a, T: ?Sized + 'a> {
lock: &'a RwLock<T>,
diff --git a/src/test/ui/lint/must_not_suspend/mutex.rs b/src/test/ui/lint/must_not_suspend/mutex.rs
new file mode 100644
index 0000000000000..7bb895e7d3643
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/mutex.rs
@@ -0,0 +1,13 @@
+// edition:2018
+#![feature(must_not_suspend)]
+#![deny(must_not_suspend)]
+
+async fn other() {}
+
+pub async fn uhoh(m: std::sync::Mutex<()>) {
+ let _guard = m.lock().unwrap(); //~ ERROR `MutexGuard` held across
+ other().await;
+}
+
+fn main() {
+}
diff --git a/src/test/ui/lint/must_not_suspend/mutex.stderr b/src/test/ui/lint/must_not_suspend/mutex.stderr
new file mode 100644
index 0000000000000..69638fc20107c
--- /dev/null
+++ b/src/test/ui/lint/must_not_suspend/mutex.stderr
@@ -0,0 +1,26 @@
+error: `MutexGuard` held across a suspend point, but should not be
+ --> $DIR/mutex.rs:8:9
+ |
+LL | let _guard = m.lock().unwrap();
+ | ^^^^^^
+LL | other().await;
+ | ------------- the value is held across this suspend point
+ |
+note: the lint level is defined here
+ --> $DIR/mutex.rs:3:9
+ |
+LL | #![deny(must_not_suspend)]
+ | ^^^^^^^^^^^^^^^^
+note: Holding a MutexGuard across suspend points can cause deadlocks, delays, and cause Future's to not implement `Send`
+ --> $DIR/mutex.rs:8:9
+ |
+LL | let _guard = m.lock().unwrap();
+ | ^^^^^^
+help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
+ --> $DIR/mutex.rs:8:9
+ |
+LL | let _guard = m.lock().unwrap();
+ | ^^^^^^
+
+error: aborting due to previous error
+
From 4cc3297dc403e9d4d2106b26418efe35d4bb1af2 Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Mon, 27 Sep 2021 08:49:36 -0700
Subject: [PATCH 2/3] #[feature] not required for lint result
---
src/test/ui/lint/must_not_suspend/mutex.rs | 1 -
src/test/ui/lint/must_not_suspend/mutex.stderr | 8 ++++----
2 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/src/test/ui/lint/must_not_suspend/mutex.rs b/src/test/ui/lint/must_not_suspend/mutex.rs
index 7bb895e7d3643..596249b2e4e4f 100644
--- a/src/test/ui/lint/must_not_suspend/mutex.rs
+++ b/src/test/ui/lint/must_not_suspend/mutex.rs
@@ -1,5 +1,4 @@
// edition:2018
-#![feature(must_not_suspend)]
#![deny(must_not_suspend)]
async fn other() {}
diff --git a/src/test/ui/lint/must_not_suspend/mutex.stderr b/src/test/ui/lint/must_not_suspend/mutex.stderr
index 69638fc20107c..47a84fdbc5731 100644
--- a/src/test/ui/lint/must_not_suspend/mutex.stderr
+++ b/src/test/ui/lint/must_not_suspend/mutex.stderr
@@ -1,5 +1,5 @@
error: `MutexGuard` held across a suspend point, but should not be
- --> $DIR/mutex.rs:8:9
+ --> $DIR/mutex.rs:7:9
|
LL | let _guard = m.lock().unwrap();
| ^^^^^^
@@ -7,17 +7,17 @@ LL | other().await;
| ------------- the value is held across this suspend point
|
note: the lint level is defined here
- --> $DIR/mutex.rs:3:9
+ --> $DIR/mutex.rs:2:9
|
LL | #![deny(must_not_suspend)]
| ^^^^^^^^^^^^^^^^
note: Holding a MutexGuard across suspend points can cause deadlocks, delays, and cause Future's to not implement `Send`
- --> $DIR/mutex.rs:8:9
+ --> $DIR/mutex.rs:7:9
|
LL | let _guard = m.lock().unwrap();
| ^^^^^^
help: consider using a block (`{ ... }`) to shrink the value's scope, ending before the suspend point
- --> $DIR/mutex.rs:8:9
+ --> $DIR/mutex.rs:7:9
|
LL | let _guard = m.lock().unwrap();
| ^^^^^^
From cb8e83caeba7268ebb3515468d348aea7af9fdae Mon Sep 17 00:00:00 2001
From: Gus Wynn <guswynn@gmail.com>
Date: Tue, 28 Sep 2021 17:57:08 -0700
Subject: [PATCH 3/3] ref/refmut
---
library/core/src/cell.rs | 10 ++++++++++
library/core/src/lib.rs | 1 +
library/std/src/sync/mutex.rs | 2 +-
library/std/src/sync/rwlock.rs | 2 +-
src/test/ui/lint/must_not_suspend/mutex.stderr | 2 +-
5 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/library/core/src/cell.rs b/library/core/src/cell.rs
index e56b631dbaf8d..c0121eebb7fef 100644
--- a/library/core/src/cell.rs
+++ b/library/core/src/cell.rs
@@ -1303,6 +1303,11 @@ impl Clone for BorrowRef<'_> {
///
/// See the [module-level documentation](self) for more.
#[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(
+ not(bootstrap),
+ must_not_suspend = "Holding a Ref across suspend \
+ points can cause BorrowErrors"
+)]
pub struct Ref<'b, T: ?Sized + 'b> {
value: &'b T,
borrow: BorrowRef<'b>,
@@ -1679,6 +1684,11 @@ impl<'b> BorrowRefMut<'b> {
///
/// See the [module-level documentation](self) for more.
#[stable(feature = "rust1", since = "1.0.0")]
+#[cfg_attr(
+ not(bootstrap),
+ must_not_suspend = "Holding a RefMut across suspend \
+ points can cause BorrowErrors"
+)]
pub struct RefMut<'b, T: ?Sized + 'b> {
value: &'b mut T,
borrow: BorrowRefMut<'b>,
diff --git a/library/core/src/lib.rs b/library/core/src/lib.rs
index 265ba9f1bb91b..2230461b5f4b5 100644
--- a/library/core/src/lib.rs
+++ b/library/core/src/lib.rs
@@ -141,6 +141,7 @@
#![feature(link_llvm_intrinsics)]
#![feature(llvm_asm)]
#![feature(min_specialization)]
+#![cfg_attr(not(bootstrap), feature(must_not_suspend))]
#![feature(negative_impls)]
#![feature(never_type)]
#![feature(no_core)]
diff --git a/library/std/src/sync/mutex.rs b/library/std/src/sync/mutex.rs
index 9abd4b547c77e..06a97fd3f7610 100644
--- a/library/std/src/sync/mutex.rs
+++ b/library/std/src/sync/mutex.rs
@@ -192,7 +192,7 @@ unsafe impl<T: ?Sized + Send> Sync for Mutex<T> {}
not(bootstrap),
must_not_suspend = "Holding a MutexGuard across suspend \
points can cause deadlocks, delays, \
- and cause Future's to not implement `Send`"
+ and cause Futures to not implement `Send`"
)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct MutexGuard<'a, T: ?Sized + 'a> {
diff --git a/library/std/src/sync/rwlock.rs b/library/std/src/sync/rwlock.rs
index 1523d36323fd9..aa1ce82d96799 100644
--- a/library/std/src/sync/rwlock.rs
+++ b/library/std/src/sync/rwlock.rs
@@ -99,7 +99,7 @@ unsafe impl<T: ?Sized + Send + Sync> Sync for RwLock<T> {}
not(bootstrap),
must_not_suspend = "Holding a RwLockReadGuard across suspend \
points can cause deadlocks, delays, \
- and cause Future's to not implement `Send`"
+ and cause Futures to not implement `Send`"
)]
#[stable(feature = "rust1", since = "1.0.0")]
pub struct RwLockReadGuard<'a, T: ?Sized + 'a> {
diff --git a/src/test/ui/lint/must_not_suspend/mutex.stderr b/src/test/ui/lint/must_not_suspend/mutex.stderr
index 47a84fdbc5731..4e0d9343c2c71 100644
--- a/src/test/ui/lint/must_not_suspend/mutex.stderr
+++ b/src/test/ui/lint/must_not_suspend/mutex.stderr
@@ -11,7 +11,7 @@ note: the lint level is defined here
|
LL | #![deny(must_not_suspend)]
| ^^^^^^^^^^^^^^^^
-note: Holding a MutexGuard across suspend points can cause deadlocks, delays, and cause Future's to not implement `Send`
+note: Holding a MutexGuard across suspend points can cause deadlocks, delays, and cause Futures to not implement `Send`
--> $DIR/mutex.rs:7:9
|
LL | let _guard = m.lock().unwrap();