[Concurrency] Diagnose mutating accesses to locals from concurrent code. #35660
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The async handler code doesn't really run concurrently with where it is launched, despite the implementation currently using `runDetached` internally. Drop the @Concurrent and bitcase it back on when needed.
Add @Concurrent to SIL function types, mirroring what's available on AST function types. @Concurrent function types will have by-value capture semantics.
Replace the existing warning about any access to a local variable from concurrently-executing code with a more tailored error: concurrently-executing code may read a mutable varable, but cannot modify it. This is safe so long as we either always do by-value captures in concurrent closures or we ensure that no mutation of that variable can occur after the point of capture. We'll follow up with one of those. For now... be careful out there. Since we're promoting this to an error, narrow it down to concurrent closures and local functions, dropping the assumption that escaping closures "may execute concurrently."
…unctions. Concurrent closures and functions are, of course... concurrent. Treat them as such for the warnings about unsafe accesses to global variables.
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@swift-ci please smoke test |
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Replace the existing warning about any access to a local variable from
concurrently-executing code with a more tailored error:
concurrently-executing code may read a mutable varable, but cannot
modify it. This is safe so long as we either always do by-value
captures in concurrent closures or we ensure that no mutation of that
variable can occur after the point of capture.
We'll follow up with one of those. For now... be careful out there.
Since we're promoting this to an error, narrow it down to concurrent
closures and local functions, dropping the assumption that escaping
closures "may execute concurrently."