1. Removes gating on -enable-experimental-concurrency.
2. Updates eff. prop tests to remove experimental flag,
and also adjusts some tests slightly to avoid things
that are still behind that flag.
- Introduce an UnownedSerialExecutor type into the concurrency library.
- Create a SerialExecutor protocol which allows an executor type to
change how it executes jobs.
- Add an unownedExecutor requirement to the Actor protocol.
- Change the ABI for ExecutorRef so that it stores a SerialExecutor
witness table pointer in the implementation field. This effectively
makes ExecutorRef an `unowned(unsafe) SerialExecutor`, except that
default actors are represented without a witness table pointer (just
a bit-pattern).
- Synthesize the unownedExecutor method for default actors (i.e. actors
that don't provide an unownedExecutor property).
- Make synthesized unownedExecutor properties `final`, and give them
a semantics attribute specifying that they're for default actors.
- Split `Builtin.buildSerialExecutorRef` into a few more precise
builtins. We're not using the main-actor one yet, though.
Pitch thread:
https://forums.swift.org/t/support-custom-executors-in-swift-concurrency/44425
Implicitly-generated interpolation variables are mutated within the
autoclosures created by a `spawn let`. Don't complain about them being
concurrently accessed, because they aren't.
Fixes rdar://76020473.
Actor inheritance was removed in the second revision of SE-0306. Remove
the ability to inherit actors.
Note that this doesn't fully eliminate all vestigates of inheritance
from actors. There are simplifications that need to be performed
still, e.g., there's no need to distinguish
designated/convenience/required initializers. That will follow.
In Swift 5.4, this worked:
func foo(_: (() throws -> ())? = nil) rethrows {}
foo() // no 'try' needed
However, this was an accident, because this was also accepted:
func foo(_: (() throws -> ())? = { throw ... }) rethrows {}
foo() // 'try' *should* be required here
This got fixed at some point recently, but since people rely on the
old case working for 'nil', let's add back a check for a 'nil'
default parameter.
Fixes rdar://problem/76169080.
They're currently incompatible, but it should be
possible to enable this, with some care taken to
ensure that effectful wrappers are composed
correctly.
The first test case added ideally shouldn't have any expected error or diagnostic.
However, due to SR-1534, there is an error emitted here. Thus, an expected error is
used here to show the compiler's behavior today.
If SR-1534 is fixed in the future, the first test case should no longer have any
expected error nor an expected note. However, the second test case should still be
left alone.
Addresses SR-14270
To help support incremental adoption of the concurrency model, a number
of concurrency-related diagnostics are enabled only in "new" code that
takes advantage of concurrency features---async, @concurrent functions,
actors, etc. This warning flag opts into additional warnings that better
approximate the eventual concurrency model, and which will become
errors a future Swift version, allowing one to both experiment with
the full concurrency model and also properly prepare for it.
The backs out of some early decisions we made about actor layout
that we don't need. Custom actors will use a different approach.
This should suffice for the remainder of rdar://70146827.
