Instead, use the `%target-swift-5.1-abi-triple` substitution to compile the tests
for deployment to the minimum OS versions required for use of _Concurrency APIs.
* Enable running tests from test/Concurrency/ directory in freestanding/minimal presets
* Mark failing Concurrency tests as XFAIL/SKIP on freestanding/minimal
The concurrency runtime now deploys back to macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, which corresponds to the 5.1 release of the stdlib.
Adjust macro usages accordingly.
Rather than blanket-disabling concurrency tests when we aren't using a
just-built concurrency library, enable them whenever we have a
suitable concurrency runtime, either just-built, in the OS, or via the
back-deployment libraries.
It breaks withCheckedContinuation.
I have not gotten to the bottom of why. But for now disable the pass for
all async functions until we can fix it.
rdar://77166575
This allows programs to target older OSes while using Concurrency behind an availability check. When targeting older OSes, the symbols are weak-linked and the compiler will require the use of Concurrency features to be guarded by an availability check.
rdar://75850003
To help catch runtime issues adopting `withUnsafeContinuation`, such as callback-based APIs that misleadingly
invoke their callback multiple times and/or not at all, provide a couple of classes that can take ownership of
a fresh `UnsafeContinuation` or `UnsafeThrowingContinuation`, and log attempts to resume the continuation multiple times
or discard the object without ever resuming the continuation.
