[6.0][region-isolation] Treat async let as a isolation inference boundary closure and fix diagnostics due to change. #75080
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This is triggered by the test case in the next commit. The problem is anonymous closures can be passed here and they do not have a ValueDecl so there isn't a decl for us to use. (cherry picked from commit 57392b1)
…closure and fix diagnostics due to change.
Otherwise, we will assume that an async let autoclosure infers isolation from
its DeclContext... which we do not want. An async let autoclosure should always
be nonisolated + sending.
The diagnostic change that I mentioned in the header is that we were emitting
unfortunate "sending task or actor isolated could result in races" error. I
eliminated this by adding a new diagnostic for transfer non transferrable errors
happening in autoclosures. So now we emit this:
```swift
func asyncLetInferAsNonIsolated<T : Actor>(
isolation actor: isolated T
) async throws {
async let subTask: Void = {
await useValueAsyncNoReturnWithInstance(self, actor)
// expected-warning @-1:47 {{sending 'self' risks causing data races}}
// expected-note @-2 {{sending 'actor'-isolated 'self' into async let risks causing data races between nonisolated and 'actor'-isolated uses}}
}()
await subTask
```
I also noticed that we did not have enough test cases for autoclosures in
general so I also added a bunch of tests just so we can see what the current
behavior is. I think there are a few issues therein (I believe some may have
been reported due to '??').
rdar://130151318
(cherry picked from commit 03b26fd)
|
@swift-ci test |
DougGregor
approved these changes
Jul 8, 2024
|
FYI, I found another radar that this fixes. I added it to the PR description. |
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Explanation: Previously, we would infer async let's auto closure isolation from its DeclContext. I noticed this due to cases where async let was getting an actor instance's isolation. That is incorrect since an async let autoclosure should always
be nonisolated + sending.
The diagnostic change that I mentioned in the header is that we were emitting
unfortunate "sending task or actor isolated could result in races" error. I
eliminated this by adding a new diagnostic for transfer non transferrable errors
happening in autoclosures. So now we emit this:
Radars:
Original PRs:
Risk: Low. This only affects auto closures that work with async lets. We definitely want this since this could potentially affect source stability. That being said since it only should affect diagnostics this is safe to take (the task the async let runs is defined by other parts of the compiler, not by this code).
Testing: Added/Ran tests
Reviewer: N/A