[Concurrency] Implement parsing and semantic analysis of await operator #33199
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Similar to `try`, await expressions have no specific semantics of their own except to indicate that the subexpression contains calls to `async` functions, which are suspension points. In this design, there can be multiple such calls within the subexpression of a given `await`. Note that we currently use the keyword `__await` because `await` in this position introduces grammatical ambiguities. We'll wait until later to sort out the specific grammar we want and evaluate source-compatibility tradeoffs. It's possible that this kind of prefix operator isn't what we want anyway.
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@swift-ci please smoke test |
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Scavenged from #11501, which was good code that just needed a little love after sitting idle for 3 years. |
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| // Generate more specific messages in some cases. | ||
| if (auto e = dyn_cast_or_null<ApplyExpr>(E.dyn_cast<Expr*>())) |
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Nit: Not important, but question is if could this be a place to use getAsExpr<ApplyExpr>(E)?
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Probably. I don't think that function existed when this was originally written ;)
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@LucianoPAlmeida It's defined in ConstraintSystem. I am not sure if it's worth importing it here to use getAsExpr though... (maybe it should be moved into ASTNode?)
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Ah true @theblixguy, so maybe move to a more general header file (as you suggested) would be nice to allow use in other places :)
Similar to
try, await expressions have no specific semantics of theirown except to indicate that the subexpression contains calls to
asyncfunctions, which are suspension points. In this design, there can be
multiple such calls within the subexpression of a given
await.Note that we currently use the keyword
__awaitbecauseawaitinthis position introduces grammatical ambiguities. We'll wait until
later to sort out the specific grammar we want and evaluate
source-compatibility tradeoffs. It's possible that this kind of prefix
operator isn't what we want anyway.