[unused_async]: don't lint if paths reference async fn without immediate call#11200
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| // Depending on how `x` is used, f's asyncness might be required despite not having any `await` | ||
| // statements, so don't lint at all if there are any such paths. |
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I believe this can use #11166 once that's merged, that way some cases are still linted
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This is unlikely to be the case. The signatures of the two functions are incompatible.
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Thank you. @bors r+ |
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[`unused_async`]: don't lint if paths reference async fn without immediate call Fixes #9695 Fixes #9359 Clippy shouldn't lint unused `async` if there are paths referencing them if that path isn't the receiver of a function call, because that means that the function might be passed to some other function: ```rs async fn f() {} // No await statements, so unused at this point fn requires_fn_future<F: Future<Output = ()>>(_: fn() -> F) {} requires_fn_future(f); // `f`'s asyncness is actually not unused. ``` (This isn't limited to just passing the function as a parameter to another function, it could also first be stored in a variable and later passed to another function as an argument) This requires delaying the linting until post-crate and collecting path references to local async functions along the way. [`unused_async`]: don't lint if paths reference async fn that require asyncness
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💔 Test failed - checks-action_test |
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oops, I must have deleted the changelog word from the pr description again somehow. It's fixed now |
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@bors retry |
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☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test |
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Remove method call receiver special casing in `unused_async` lint Fixes the false positive mentioned in #13466 (comment). The false negative in the OP would be nice to fix too, but I'd rather do that in a separate PR because it's much more involved Before this change, the `unused_async` lint would check if the async fn is also used anywhere and avoid linting if so. The exception is if the async function is immediately called, because the returned future handling can be easily removed (and also if we don't have some exceptions then the lint wouldn't trigger anywhere) *or* if it's a method call receiver. I'm not exactly sure why I implemented that special casing for method call receivers in #11200, but it doesn't make much sense in hindsight imo. Especially given that method calls are essentially equivalent to function calls with the receiver as the first argument, which was the primary motivation for not linting in the first place (async fn passed to another function, like `axum::get(handler)` where handler has to be an async fn). changelog: none
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Fixes #9695
Fixes #9359
Clippy shouldn't lint unused
asyncif there are paths referencing them if that path isn't the receiver of a function call, because that means that the function might be passed to some other function:(This isn't limited to just passing the function as a parameter to another function, it could also first be stored in a variable and later passed to another function as an argument)
This requires delaying the linting until post-crate and collecting path references to local async functions along the way.
changelog: [
unused_async]: don't lint if paths reference async fn that require asyncness