This is in order to avoid errors in complete concurrency checking mnode
in distributed funcs, or rather their thunks, as there is isolation
boundary crossing happening when we pass a value to a distributed func.
This is because as we do this, we pass it to a nonisolated thunk:
```
nonisolated func THUNK(param: Thing) {
if remote {
...
} else {
await self.realFunc(param)
}
}
```
So what happens here is that the Thing would become isolated to the
task and we get a bad isolation crossing as we pass it along to the
"real func".
Sending values into the distributed thunk is the right thing to do to
resolve this problem: `nonisolated func THUNK(param: sending Thing) {}`
Resolves rdar://126577527
Obsoleting `AnyActor` in Swift 6 blocks the Concurrency library itself
from migrating to Swift 6, because `Actor` and `DistributedActor` have to
preserve their refinement of `AnyActor` to avoid breaking code currently
using the marker protocol. There's no way to move protocol refinement into
an extension so that the use-site declaration can be obsoleted, so we're
stuck with just the deprecation of `AnyActor`.
When diagnosing a case where an actor-isolated witness cannot satisfy
a non-isolated requirement, also suggest that the conformance could be
annotated with `@preconcurrency`.
The macro cannot diagnose some situations, or rather, would diagnose too
aggressively, because it cannot inspect the type declarations of all
invokved types, and therefore we're unable to reliably report errors
only when necessary.
Originally I thought we don't want to emit macro code that "may fail to
compile" but we don't really have a choice.
This patch removes a manual diagnostic, and enables more correct code to
properly use @Resolvable protocols.
This ensures that we can properly compute isolation for generic types that
conform to AnyActor.
I found this by playing with test cases from the previous commit. We would not
find an actor type for the actor instance isolation and would fall back along an
incorrect path.
rdar://128021548
As part of this I went through how we handled inference and rather than using a
grab-bag getActorIsolation that was confusing to use, I created split APIs for
specific use cases (actor instance, global actor, just an apply expr crossing)
that makes it clearer inside the SILIsolationInfo::get* APIs what we are
actually trying to model. I found a few issues as a result and fixed most of
them if they were small. I also fixed one bigger one around computed property
initializers in the next commit. There is a larger change I didn't fix around allowing function
ref/partial_apply with isolated self parameters have a delayed flow sensitive
actor isolation... this will be fixed in a subsequent commit.
This also fixes a bunch of cases where we were printing actor-isolated instead
of 'self' isolated.
rdar://127295657
We changed to `llvm.compiler.used` because of the behaviour of `gold`,
which refuses to coalesce sections that have different `SHF_GNU_RETAIN`
flags, which causes problems with metadata.
Originally I thought we were going to have to generate two sections
with distinct names and have the runtime look for both of them, but
it turns out that the runtime only wants to see sections that have
`SHF_GNU_RETAIN` in any case. It's really the reflection code that
is interested in being able to see non-retained sections. The upshot
is that we don't need to use `llvm.compiler.used`; it's just fine if
we have duplicate sections, as long as the reflection code looks for
them when it's inspecting an ELF image.
This also means we no longer need to pass `-z nostart-stop-gc` to the
linker if we're using `lld`.
rdar://123504095
Failing to map the type of an isolation capture into context
caused assertions in type lowering. Fixes the build of the
swift-distributed-actors package.
First, and I really should've checked this, but global actors do not
require `shared` to return `Self`; adjust the logic to propagate the
right formal type to the erasure logic.
Second, handle attempts to erase the isolation of something isolated to
a distributed actor using the magic Actor conformance that Doug added.
This only works when the actor is local, but it shouldn't be difficult to
enforce that we only attempt to erase isolation what that's true --- we
need to prevent partial application of distributed actors, and we need to
disallow explicit isolated captures of distributed actors when we're not
currently isolated to it. Otherwise, it's not possible to get an
@isolated(any) function value with an isolation that isn't the current
function's isolation, which means it always has to be local.
Fixed rdar://123734019
