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Auto merge of #12609 - Alexendoo:arc-with-non-send-sync-message, r=Jarcho

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Reword `arc_with_non_send_sync` note and help messages

Addresses https://github.com/rust-lang/rust-clippy/issues/12608#issuecomment-2029688054

Makes the note more concise and reframes the `Rc` suggestion around whether it crosses threads currently due to a manual `Send`/`Sync` impl or may do in the future

changelog: none
This commit is contained in:
bors 2024-04-04 21:59:21 +00:00
commit a73e751d19
3 changed files with 22 additions and 40 deletions
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26
clippy_lints/src/arc_with_non_send_sync.rs
View File

@ -56,7 +56,12 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
&& let Some(send) = cx.tcx.get_diagnostic_item(sym::Send)
&& let Some(sync) = cx.tcx.lang_items().sync_trait()
&& let [is_send, is_sync] = [send, sync].map(|id| implements_trait(cx, arg_ty, id, &[]))
&& !(is_send && is_sync)
&& let reason = match (is_send, is_sync) {
(false, false) => "neither `Send` nor `Sync`",
(false, true) => "not `Send`",
(true, false) => "not `Sync`",
_ => return,
}
&& !is_from_proc_macro(cx, expr)
{
span_lint_and_then(
@ -66,21 +71,12 @@ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
"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}`"));
}
if !is_sync {
diag.note(format!("- the trait `Sync` is not implemented for `{arg_ty}`"));
}
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.note(format!(
"wrap the inner type with a `Mutex` or implement `Send` and `Sync` for `{arg_ty}`"
"`Arc<{arg_ty}>` is not `Send` and `Sync` as `{arg_ty}` is {reason}"
));
diag.help("if the `Arc` will not used be across threads replace it with an `Rc`");
diag.help(format!(
"otherwise make `{arg_ty}` `Send` and `Sync` or consider a wrapper type such as `Mutex`"
));
});
},

7
tests/ui/arc_with_non_send_sync.rs
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@ -33,16 +33,9 @@ fn main() {
let _ = Arc::new(42);
let _ = Arc::new(RefCell::new(42));
//~^ 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` 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` and `Sync`
//~| NOTE: the trait `Send` is not implemented for `*const i32`
//~| NOTE: the trait `Sync` is not implemented for `*const i32`
}

29
tests/ui/arc_with_non_send_sync.stderr
View File

@ -4,38 +4,31 @@ error: usage of an `Arc` that is not `Send` and `Sync`
LL | let _ = Arc::new(RefCell::new(42));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= 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: `Arc<RefCell<i32>>` is not `Send` and `Sync` as `RefCell<i32>` is not `Sync`
= help: if the `Arc` will not used be across threads replace it with an `Rc`
= help: otherwise make `RefCell<i32>` `Send` and `Sync` or consider a wrapper type such as `Mutex`
= 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` and `Sync`
--> tests/ui/arc_with_non_send_sync.rs:40:13
--> tests/ui/arc_with_non_send_sync.rs:38:13
|
LL | let _ = Arc::new(mutex.lock().unwrap());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= 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>`
= note: `Arc<MutexGuard<'_, i32>>` is not `Send` and `Sync` as `MutexGuard<'_, i32>` is not `Send`
= help: if the `Arc` will not used be across threads replace it with an `Rc`
= help: otherwise make `MutexGuard<'_, i32>` `Send` and `Sync` or consider a wrapper type such as `Mutex`
error: usage of an `Arc` that is not `Send` and `Sync`
--> tests/ui/arc_with_non_send_sync.rs:44:13
--> tests/ui/arc_with_non_send_sync.rs:40:13
|
LL | let _ = Arc::new(&42 as *const i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= 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`
= note: `Arc<*const i32>` is not `Send` and `Sync` as `*const i32` is neither `Send` nor `Sync`
= help: if the `Arc` will not used be across threads replace it with an `Rc`
= help: otherwise make `*const i32` `Send` and `Sync` or consider a wrapper type such as `Mutex`
error: aborting due to 3 previous errors