diff options
| -rw-r--r-- | clippy_lints/src/arc_with_non_send_sync.rs | 22 | ||||
| -rw-r--r-- | tests/ui/arc_with_non_send_sync.rs | 6 | ||||
| -rw-r--r-- | tests/ui/arc_with_non_send_sync.stderr | 32 |
3 files changed, 37 insertions, 23 deletions
diff --git a/clippy_lints/src/arc_with_non_send_sync.rs b/clippy_lints/src/arc_with_non_send_sync.rs index 192bc7d9ddc..9799e703afe 100644 --- a/clippy_lints/src/arc_with_non_send_sync.rs +++ b/clippy_lints/src/arc_with_non_send_sync.rs @@ -14,7 +14,9 @@ declare_clippy_lint! { /// This lint warns when you use `Arc` with a type that does not implement `Send` or `Sync`. /// /// ### Why is this bad? - /// `Arc<T>` is only `Send`/`Sync` when `T` is [both `Send` and `Sync`](https://doc.rust-lang.org/std/sync/struct.Arc.html#impl-Send-for-Arc%3CT%3E), + /// `Arc<T>` is an Atomic `RC<T>` and guarantees that updates to the reference counter are + /// Atomic. This is useful in multiprocessing scenarios. To send an `Arc<T>` across processes + /// and make use of the atomic ref counter, `T` must be [both `Send` and `Sync`](https://doc.rust-lang.org/std/sync/struct.Arc.html#impl-Send-for-Arc%3CT%3E), /// either `T` should be made `Send + Sync` or an `Rc` should be used instead of an `Arc` /// /// ### Example @@ -34,7 +36,7 @@ declare_clippy_lint! { #[clippy::version = "1.72.0"] pub ARC_WITH_NON_SEND_SYNC, suspicious, - "using `Arc` with a type that does not implement `Send` or `Sync`" + "using `Arc` with a type that does not implement `Send` and `Sync`" } declare_lint_pass!(ArcWithNonSendSync => [ARC_WITH_NON_SEND_SYNC]); @@ -61,19 +63,25 @@ impl<'tcx> LateLintPass<'tcx> for ArcWithNonSendSync { cx, ARC_WITH_NON_SEND_SYNC, expr.span, - "usage of an `Arc` that is not `Send` or `Sync`", + "usage of an `Arc` that is not `Send` and `Sync`", |diag| { with_forced_trimmed_paths!({ + diag.note(format!("`Arc<{arg_ty}>` is not `Send` and `Sync` as:")); + if !is_send { - diag.note(format!("the trait `Send` is not implemented for `{arg_ty}`")); + diag.note(format!("- the trait `Send` is not implemented for `{arg_ty}`")); } if !is_sync { - diag.note(format!("the trait `Sync` is not implemented for `{arg_ty}`")); + diag.note(format!("- the trait `Sync` is not implemented for `{arg_ty}`")); } - diag.note(format!("required for `{ty}` to implement `Send` and `Sync`")); + diag.help("consider using an `Rc` instead. `Arc` does not provide benefits for non `Send` and `Sync` types"); + + diag.note("if you intend to use `Arc` with `Send` and `Sync` traits"); - diag.help("consider using an `Rc` instead or wrapping the inner type with a `Mutex`"); + diag.note(format!( + "wrap the inner type with a `Mutex` or implement `Send` and `Sync` for `{arg_ty}`" + )); }); }, ); diff --git a/tests/ui/arc_with_non_send_sync.rs b/tests/ui/arc_with_non_send_sync.rs index d03a577c454..349e81912e3 100644 --- a/tests/ui/arc_with_non_send_sync.rs +++ b/tests/ui/arc_with_non_send_sync.rs @@ -33,16 +33,16 @@ fn main() { let _ = Arc::new(42); let _ = Arc::new(RefCell::new(42)); - //~^ ERROR: usage of an `Arc` that is not `Send` or `Sync` + //~^ ERROR: usage of an `Arc` that is not `Send` and `Sync` //~| NOTE: the trait `Sync` is not implemented for `RefCell<i32>` let mutex = Mutex::new(1); let _ = Arc::new(mutex.lock().unwrap()); - //~^ ERROR: usage of an `Arc` that is not `Send` or `Sync` + //~^ ERROR: usage of an `Arc` that is not `Send` and `Sync` //~| NOTE: the trait `Send` is not implemented for `MutexGuard<'_, i32>` let _ = Arc::new(&42 as *const i32); - //~^ ERROR: usage of an `Arc` that is not `Send` or `Sync` + //~^ ERROR: usage of an `Arc` that is not `Send` and `Sync` //~| NOTE: the trait `Send` is not implemented for `*const i32` //~| NOTE: the trait `Sync` is not implemented for `*const i32` } diff --git a/tests/ui/arc_with_non_send_sync.stderr b/tests/ui/arc_with_non_send_sync.stderr index fd239580d28..a7f91abda4e 100644 --- a/tests/ui/arc_with_non_send_sync.stderr +++ b/tests/ui/arc_with_non_send_sync.stderr @@ -1,35 +1,41 @@ -error: usage of an `Arc` that is not `Send` or `Sync` +error: usage of an `Arc` that is not `Send` and `Sync` --> $DIR/arc_with_non_send_sync.rs:35:13 | LL | let _ = Arc::new(RefCell::new(42)); | ^^^^^^^^^^^^^^^^^^^^^^^^^^ | - = note: the trait `Sync` is not implemented for `RefCell<i32>` - = note: required for `Arc<RefCell<i32>>` to implement `Send` and `Sync` - = help: consider using an `Rc` instead or wrapping the inner type with a `Mutex` + = note: `Arc<RefCell<i32>>` is not `Send` and `Sync` as: + = note: - the trait `Sync` is not implemented for `RefCell<i32>` + = help: consider using an `Rc` instead. `Arc` does not provide benefits for non `Send` and `Sync` types + = note: if you intend to use `Arc` with `Send` and `Sync` traits + = note: wrap the inner type with a `Mutex` or implement `Send` and `Sync` for `RefCell<i32>` = note: `-D clippy::arc-with-non-send-sync` implied by `-D warnings` = help: to override `-D warnings` add `#[allow(clippy::arc_with_non_send_sync)]` -error: usage of an `Arc` that is not `Send` or `Sync` +error: usage of an `Arc` that is not `Send` and `Sync` --> $DIR/arc_with_non_send_sync.rs:40:13 | LL | let _ = Arc::new(mutex.lock().unwrap()); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | - = note: the trait `Send` is not implemented for `MutexGuard<'_, i32>` - = note: required for `Arc<MutexGuard<'_, i32>>` to implement `Send` and `Sync` - = help: consider using an `Rc` instead or wrapping the inner type with a `Mutex` + = note: `Arc<MutexGuard<'_, i32>>` is not `Send` and `Sync` as: + = note: - the trait `Send` is not implemented for `MutexGuard<'_, i32>` + = help: consider using an `Rc` instead. `Arc` does not provide benefits for non `Send` and `Sync` types + = note: if you intend to use `Arc` with `Send` and `Sync` traits + = note: wrap the inner type with a `Mutex` or implement `Send` and `Sync` for `MutexGuard<'_, i32>` -error: usage of an `Arc` that is not `Send` or `Sync` +error: usage of an `Arc` that is not `Send` and `Sync` --> $DIR/arc_with_non_send_sync.rs:44:13 | LL | let _ = Arc::new(&42 as *const i32); | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ | - = note: the trait `Send` is not implemented for `*const i32` - = note: the trait `Sync` is not implemented for `*const i32` - = note: required for `Arc<*const i32>` to implement `Send` and `Sync` - = help: consider using an `Rc` instead or wrapping the inner type with a `Mutex` + = note: `Arc<*const i32>` is not `Send` and `Sync` as: + = note: - the trait `Send` is not implemented for `*const i32` + = note: - the trait `Sync` is not implemented for `*const i32` + = help: consider using an `Rc` instead. `Arc` does not provide benefits for non `Send` and `Sync` types + = note: if you intend to use `Arc` with `Send` and `Sync` traits + = note: wrap the inner type with a `Mutex` or implement `Send` and `Sync` for `*const i32` error: aborting due to 3 previous errors |