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Disable ExistentialAny temporarily #10

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czechboy0
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Motivation

Unfortunately until we adopt 5.9, adding ExistentialAny on upstream packages has unintended consequences for some downstream packages, so disabling for now. Details in apple/swift-openapi-generator#120

Modifications

Disabled the feature enforcement, but the code changes are there, so downstream adopters can still use them.

Result

We won't be seeing the issue described in apple/swift-openapi-generator#120.

Test Plan

PR CI, which discovered the original issue.

@czechboy0 czechboy0 requested a review from simonjbeaumont July 17, 2023 07:41
@simonjbeaumont
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Rather than just disable it everywhere, let's enable it in just the Swift 5.9+ builds, by adding -Xswiftc -enable-upcoming-feature -Xswiftc ExistentialAny to the 5.9 and nightly docker-compose files.

This way we won't regress.

@FranzBusch
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Rather than just disable it everywhere, let's enable it in just the Swift 5.9+ builds, by adding -Xswiftc -enable-upcoming-feature -Xswiftc ExistentialAny to the 5.9 and nightly docker-compose files.

What about adding a #if to the Package.swift so that also in local development we get this. I would prefer that over a flag just on the CI.

@czechboy0 czechboy0 merged commit f6e6c2f into apple:main Jul 17, 2023
@czechboy0 czechboy0 deleted the hd-disable-existential-any-temporarily branch July 17, 2023 09:26
@czechboy0 czechboy0 added the semver/none No version bump required. label Jul 17, 2023
simonjbeaumont added a commit that referenced this pull request Jan 16, 2024
…#46)

### Motivation

When running the cancellation tests in a loop, very occasionally there
would be a crash with the following backtrace:

```
#0	0x000000018aa008d4 in objc_opt_respondsToSelector ()
#1	0x000000018aea3410 in _outputStreamCallbackFunc ()
#2	0x000000018aea3310 in _signalEventSync ()
#3	0x000000018aeecdb0 in ___signalEventQueue_block_invoke ()
#4	0x000000018abe6cb8 in _dispatch_call_block_and_release ()
#5	0x000000018abe8910 in _dispatch_client_callout ()
#6	0x000000018abefea4 in _dispatch_lane_serial_drain ()
#7	0x000000018abf0a08 in _dispatch_lane_invoke ()
#8	0x000000018abfb61c in _dispatch_root_queue_drain_deferred_wlh ()
#9	0x000000018abfae90 in _dispatch_workloop_worker_thread ()
#10	0x000000018ad96114 in _pthread_wqthread ()
```

This seems to indicate that the output stream is trying to access its
delegate. However, when running with debug logging enabled I can see
that the delegate has already been deinitialized.

This is likely a result of the delegate itself owning the stream and
setting the stream delegate to `self`, which IIUC is an established
pattern. This presents a race in teardown.

### Modifications

This patch sets the output stream delegate to `nil` in the delegate
`deinit`.

### Result

No attempts to call the delegate will happen after it is has been
deinitailzed.

### Test Plan

With this patch, the failing test passes when run an order of magnitude
more times than were required to reliably reproduce the crash without
the patch.
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3 participants