[Concurrency] Fix async-main crash #36201
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| @@ -1831,6 +1831,18 @@ synthesizeMainBody(AbstractFunctionDecl *fn, void *arg) { | |||
| Expr *returnedExpr; | |||
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| if (mainFunction->hasAsync()) { | |||
| if (!context.LangOpts.EnableExperimentalConcurrency) { | |||
| context.Diags.diagnose(mainFunction->getAsyncLoc(), | |||
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We may want a comment relating how this fixes the crash because _Concurrency implicitly gets imported when -enable-experimental-concurrency is passed in, but doesn't when it's not. If that changes, the crash comes back.
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It'll work the way it is now, but how about checking for !concurrencyModule below instead of -enable-experimental-concurrency? That would avoid the crash if the module doesn't get loaded for any reason.
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Okay, now checks against the concurrency module. Also added a test passing both -enable-experimental-concurrency and -parse-stdlib since that won't implicitly import _Concurrency either.
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@swift-ci please smoke test Windows |
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@swift-ci please smoke test windows |
| @@ -1831,6 +1831,18 @@ synthesizeMainBody(AbstractFunctionDecl *fn, void *arg) { | |||
| Expr *returnedExpr; | |||
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| if (mainFunction->hasAsync()) { | |||
| if (!context.LangOpts.EnableExperimentalConcurrency) { | |||
| context.Diags.diagnose(mainFunction->getAsyncLoc(), | |||
There was a problem hiding this comment.
It'll work the way it is now, but how about checking for !concurrencyModule below instead of -enable-experimental-concurrency? That would avoid the crash if the module doesn't get loaded for any reason.
The concurrency module gets imported implicitly when `-enable-experimental-concurrency` is passed to the compiler. If the concurrency module isn't imported, we crash on th assert verifying that we were able to find it. We need the module to lookup the `_runAsyncMain` function. This patch updates the compiler to stop type-checking the async-main function and emit an error if the module isn't available instead of crashing.
This patch adds a quick test to verify that we emit a reasonable error message when trying to use async-main without enabling concurrency or parsing as stdlib instead of crashing. Under both circumstances, the _Concurrency library won't be implicitly imported.
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The compiler would assert/crash if someone tried to use async-main without enabling concurrency since it would fail to find the concurrency module.
import _Concurrencyin the source file would also work, but is kind of gross.I've decided to go down the route of just protecting the feature behind a check for enabling concurrency. Once we have, the concurrency module is imported implicitly, and we avoid the crash. Alternatively, we could just recommend that folks import the concurrency module.
Fixes rdar://74821680