This changes the isIsolatingCurrentContext function to return `Bool?`
and removes all the witness table trickery we did previously to detect
if it was implemented or not. This comes at a cost of trying to invoke
it always, before `checkIsolated`, but it makes for an simpler
implementation and more checkable even by third party Swift code which
may want to ask this question.
Along with the `withSerialExecutor` function, this now enables us to
check the isolation at runtime when we have an `any Actor` e.g. from
`#isolation`.
Updates SE-0471 according to
https://forums.swift.org/t/se-0471-improved-custom-serialexecutor-isolation-checking-for-concurrency-runtime/78834/
review discussions
Reorganise the Concurrency code so that it's possible to completely
implement executors (both main and global) in Swift.
Provide API to choose the desired executors for your application.
Also make `Task.Sleep` wait using the current executor, not the global
executor, and expose APIs on `Clock` to allow for conversion between
time bases.
rdar://141348916
We were missing a field in `SwiftJob`, which broke various things. To
avoid that problem in future, this PR adds a set of static asserts to
check the layout of various structures and that we're using the same
values as well.
Also added some functions to the ABI, and fixed things so that if you
enable the debug logging the library still builds (there was an extra
`_` in `Actor.cpp` that caused a build failure).
Finally, renamed `Hooks.cpp` to `ConcurrencyHooks.cpp`.
rdar://135380149
`ExecutorHooks.h` is now nothing to do with hooks, so rename it. Also
there are some additional functions it should declare, and a couple of
places where we've slightly messed up the boundary, for instance
`swift_task_asyncMainDrainQueue` was defined in `Task.cpp` rather than
in the executor implementations, which is wrong, so fix that too.
`CooperativeGlobalExecutor.cpp` now builds against the interface from
`ExecutorImpl.h`, rather than including the all the concurrency headers.
rdar://135380149
