It's ok to drop the global-actor qualifier `@G` from a function's type if:
- the cast is happening in a context isolated to global-actor `G`
- the function value will not be `@Sendable`
- the function value is not `async`
It's primarily safe to drop the attribute because we're already in the
same isolation domain. So it's OK to simply drop the global-actor
if we prevent the value from later leaving that isolation domain.
This means we no longer need to warn about code like this:
```
@MainActor func doIt(_ x: [Int], _ f: @MainActor (Int) -> ()) {
x.forEach(f)
// warning: converting function value of type '@MainActor (Int) -> ()' to '(Int) throws -> Void' loses global actor 'MainActor'
}
```
NOTE: this implementation is a bit gross in that the constraint solver
might emit false warnings about casts it introduced that are actually
safe. This is mainly because closure isolation is only fully determined
after constraint solving. See the FIXME's for more details.
resolves rdar://94462333
When we get rid of `LeaveClosureBodiesUnchecked` we no longer save closure types to the AST and thus also don’t save their actor isolation to the AST. Hence, we need to extract types and actor isolations of parent closures from the constraint system solution instead of the AST. This prepares `ActorIsolationChecker` to take custom functions to determine the type of an expression or the actor isolation of a closure.
A function can be actor instance-isolated to one of its parameters.
Make sure that this is reflected in ActorIsolation, so such a function
doesn't get a different actor isolation.
[Distributed] generic and inner test; without one edge case
[Distributed] fix distributed_thunk test; unsure about those extra hops, could remove later
[Distributed] Remove type pretending in getSILFunctionType; it is not needed
It seems our constant replacement in the earlier phases is enough, and
we don't need this trick at all.
[Distributed] Use thunk when calling cross-actor on DA protocols
Start collapsing the several implementations of actor isolation checking
into a single place that determines what it means to reference a declaration
from a given context, potentially supplying an instance for an actor. This
is partly cleanup, and partly staging for the implementation of the
Sendable restrictions introduced in SE-0338. The result of this check
falls into one of three categories:
* Reference occurs within the same concurrency domain (actor/task)
* Reference leaves an actor context to a nonisolated context (SE-0338)
* Reference enters the context of the actor, which might require a
combination of implicit async, implicit throws, and a "distributed" check.
Throughout this change I've sought to maintain the existing semantics,
even where I believe they are incorrect. The changes to the test cases
are not semantic changes, but reflect the unification of some
diagnostic paths that changed the diagnostic text but not when or how
those diagnostics are produced. Additionally, SE-0338 has not yet been
implemented, although this refactoring makes it easier to implement
SE-0338.
Use this new actor isolation checking scheme to implement the most
common actor-isolation check, which occurs when accessing a member of
an instance.
With the clarification in SE-0338, revise the definition of "may
execute concurrently with" to always be false when we're accessing a
value from a same-actor-isolated inner context.
Fixes rdar://82004833.
When a closure is not properly actor-isolated, but we know that we inferred its isolation from a `@preconcurrency` declaration, we now emit the errors as warnings in Swift 5 mode to avoid breaking source compatibility if the isolation was added retroactively.
The distributed case is distinguishable from the non-distributed case
based on the actor type itself for those rare cases where we care. The
vast majority of code is simplified by treating this identically to
`ActorInstance`.
Flow-isolation is a diagnostic SIL pass that finds
unsafe accesses to properties in initializers and
deinitializers that cannot gain isolation to otherwise
protect those accesses from concurrent modifications.
See SE-327 for more details about how and why it exists.
This commit includes changes and features like:
- The removal of the escaping-use restriction
- Flow-isolation that works properly with `defer` statements
- Flow-isolation with an emphasis on helpful diagnostics.
It also includes known issues like:
- Local / nonescaping functions are not analyzed by
flow-isolation, despite it being technically possible.
The main challenge in supporting it efficiently is that
such functions do not have a single exit-point, like
a `defer`. In particular, arbitrary functions can throw
so there are points where nonisolation should _not_ flow
out of the function at a call-site in the initializer, etc.
- The implementation of the flow-isolation pass is not
particularly memory efficient; it relies on BitDataflow
even though the particular flow problem is simple.
So, a more efficient implementation would be specialized for
this particular problem, etc.
There are also some changes to the Swift language itself: defer
will respect its context when deciding its property access kind.
Previously, a defer in an initializer would always access a stored
property through its accessor methods, instead of doing so directly
like its enclosing function might. This inconsistency is unfortunate,
so for Swift 6+ we make this consistent. For Swift 5, only a defer
in a function that is a member of the following kinds of types
will gain this consistency:
- an actor type
- any nominal type that is actor-isolated, excluding UnsafeGlobalActor.
These types are still rather new, so there is much less of a chance of
breaking expected behaviors around defer. In particular, the danger is
that users are relying on the behavior of defer triggering a property
observer within an init or deinit, when it would not be triggering it
without the defer.
Improve the equality check for actor isolation to prevent differences
between "unsafe" global actor and global actor isolation from causing
inequality. The operation here is about conceptual equality, not
precise storage semantics. This allows us to simplify override
isolation checking and, likely, other places I haven't seen yet.
Previously, we were ignoring the explicit `nonisolated`
attribute on an actor initializer. This only has a
noticable effect if the initializer is `async`: an actor
hop is being emitted even though isolation was explicitly
not requested.
While we internally treat the isolation of an unadorned
actor initializer as if it were `nonisolated`, if the
programmer explicitly requests it, then it should be honored
in an async init too. Thus, this patch tells definite initialization
to skip the insertion of the hop, instead treating a `nonisolated`
initializer as though it has the escaping-use restriction.
resolves rdar://84164173
* [Distributed] Initial distributed checking
* [Distributed] initial types shapes and conform to DistributedActor
* [Distributed] Require Codable params and return types
* [Distributed] initial synthesis of fields and constructors
* [Distributed] Field and initializer synthesis
* [Distributed] Codable requirement on distributed funcs; also handle <T: Codable>
* [Distributed] handle generic type params which are Codable in dist func
[Distributed] conformsToProtocol after all
* [Distributed] Implement remote flag on actors
* Implement remote flag on actors
* add test
* actor initializer that sets remote flag
[Distributed] conformances getting there
* [Distributed] dont require async throws; cleanup compile tests
* [Distributed] do not synthesize default implicit init, only our special ones
* [Distributed] properly synth inits and properties; mark actorTransport as _distributedActorIndependent
Also:
- do not synthesize default init() initializer for dist actor
* [Distributed] init(transport:) designated and typechecking
* [Distributed] dist actor initializers MUST delegate to local-init
* [Distributed] check if any ctors in delegation call init(transport:)
* [Distributed] check init(transport:) delegation through many inits; ban invoking init(resolve:using:) explicitly
* [Distributed] disable IRGen test for now
* [Distributed] Rebase cleanups
* [Concurrent] transport and address are concurrent value
* [Distributed] introduce -enable-experimental-distributed flag
* rebase adjustments again
* rebase again...
* [Distributed] distributed functions are implicitly async+throws outside the actor
* [Distributed] implicitly throwing and async distributed funcs
* remove printlns
* add more checks to implicit function test
* [Distributed] resolve initializer now marks the isRemote actor flag
* [Distributed] distributedActor_destroy invoked instead, rather than before normal
* [Distributed] Generate distributed thunk for actors
* [distributed] typechecking for _remote_ functions existing, add tests for remote funcs
* adding one XFAIL'ed task & actor lifetime test
The `executor_deinit1` test fails 100% of the time
(from what I've seen) so I thought we could track
and see when/if someone happens to fix this bug.
Also, added extra coverage for #36298 via `executor_deinit2`
* Fix a memory issue with actors in the runtime system, by @phausler
* add new test that now passes because of patch by @phausler
See previous commit in this PR.
Test is based on one from rdar://74281361
* fix all tests that require the _remote_ function stubs
* Do not infer @actorIndependent onto `let` decls
* REVERT_ME: remove some tests that hacky workarounds will fail
* another flaky test, help build toolchain
* [Distributed] experimental distributed implies experimental concurrency
* [Distributed] Allow distributed function that are not marked async or throws
* [Distributed] make attrs SIMPLE to get serialization generated
* [Distributed] ActorAddress must be Hashable
* [Distributed] Implement transport.actorReady call in local init
* cleanup after rebase
* [Distributed] add availability attributes to all distributed actor code
* cleanup - this fixed some things
* fixing up
* fixing up
* [Distributed] introduce new Distributed module
* [Distributed] diagnose when missing 'import _Distributed'
* [Distributed] make all tests import the module
* more docs on address
* [Distributed] fixup merge issues
* cleanup: remove unnecessary code for now SIMPLE attribute
* fix: fix getActorIsolationOfContext
* [Distributed] cmake: depend on _concurrency module
* fixing tests...
* Revert "another flaky test, help build toolchain"
This reverts commit 83ae6654dd.
* remove xfail
* clenup some IR and SIL tests
* cleanup
* [Distributed] fix cmake test and ScanDependencies/can_import_with_map.swift
* [Distributed] fix flags/build tests
* cleanup: use isDistributed wherever possible
* [Distributed] don't import Dispatch in tests
* dont link distributed in stdlib unittest
* trying always append distributed module
* cleanups
* [Distributed] move all tests to Distributed/ directory
* [lit] try to fix lit test discovery
* [Distributed] update tests after diagnostics for implicit async changed
* [Distributed] Disable remote func tests on Windows for now
* Review cleanups
* [Distributed] fix typo, fixes Concurrency/actor_isolation_objc.swift
* [Distributed] attributes are DistributedOnly (only)
* cleanup
* [Distributed] cleanup: rely on DistributedOnly for guarding the keyword
* Update include/swift/AST/ActorIsolation.h
Co-authored-by: Doug Gregor <dgregor@apple.com>
* introduce isAnyThunk, minor cleanup
* wip
* [Distributed] move some type checking to TypeCheckDistributed.cpp
* [TypeCheckAttr] remove extra debug info
* [Distributed/AutoDiff] fix SILDeclRef creation which caused AutoDiff issue
* cleanups
* [lit] remove json import from lit test suite, not needed after all
* [Distributed] distributed functions only in DistributedActor protocols
* [Distributed] fix flag overlap & build setting
* [Distributed] Simplify noteIsolatedActorMember to not take bool distributed param
* [Distributed] make __isRemote not public
* [Distributed] Fix availability and remove actor class tests
* [actorIndependent] do not apply actorIndependent implicitly to values where it would be illegal to apply
* [Distributed] disable tests until issue fixed
Co-authored-by: Dario Rexin <drexin@apple.com>
Co-authored-by: Kavon Farvardin <kfarvardin@apple.com>
Co-authored-by: Doug Gregor <dgregor@apple.com>
* Revert "[Distributed] disable tests until issue fixed"
This reverts commit 0a04278920.
* Revert "[Distributed] Initial `distributed` actors and functions and new module (#37109)"
This reverts commit 814ede0cf3.
* [Distributed] Initial distributed checking
* [Distributed] initial types shapes and conform to DistributedActor
* [Distributed] Require Codable params and return types
* [Distributed] initial synthesis of fields and constructors
* [Distributed] Field and initializer synthesis
* [Distributed] Codable requirement on distributed funcs; also handle <T: Codable>
* [Distributed] handle generic type params which are Codable in dist func
[Distributed] conformsToProtocol after all
* [Distributed] Implement remote flag on actors
* Implement remote flag on actors
* add test
* actor initializer that sets remote flag
[Distributed] conformances getting there
* [Distributed] dont require async throws; cleanup compile tests
* [Distributed] do not synthesize default implicit init, only our special ones
* [Distributed] properly synth inits and properties; mark actorTransport as _distributedActorIndependent
Also:
- do not synthesize default init() initializer for dist actor
* [Distributed] init(transport:) designated and typechecking
* [Distributed] dist actor initializers MUST delegate to local-init
* [Distributed] check if any ctors in delegation call init(transport:)
* [Distributed] check init(transport:) delegation through many inits; ban invoking init(resolve:using:) explicitly
* [Distributed] disable IRGen test for now
* [Distributed] Rebase cleanups
* [Concurrent] transport and address are concurrent value
* [Distributed] introduce -enable-experimental-distributed flag
* rebase adjustments again
* rebase again...
* [Distributed] distributed functions are implicitly async+throws outside the actor
* [Distributed] implicitly throwing and async distributed funcs
* remove printlns
* add more checks to implicit function test
* [Distributed] resolve initializer now marks the isRemote actor flag
* [Distributed] distributedActor_destroy invoked instead, rather than before normal
* [Distributed] Generate distributed thunk for actors
* [distributed] typechecking for _remote_ functions existing, add tests for remote funcs
* adding one XFAIL'ed task & actor lifetime test
The `executor_deinit1` test fails 100% of the time
(from what I've seen) so I thought we could track
and see when/if someone happens to fix this bug.
Also, added extra coverage for #36298 via `executor_deinit2`
* Fix a memory issue with actors in the runtime system, by @phausler
* add new test that now passes because of patch by @phausler
See previous commit in this PR.
Test is based on one from rdar://74281361
* fix all tests that require the _remote_ function stubs
* Do not infer @actorIndependent onto `let` decls
* REVERT_ME: remove some tests that hacky workarounds will fail
* another flaky test, help build toolchain
* [Distributed] experimental distributed implies experimental concurrency
* [Distributed] Allow distributed function that are not marked async or throws
* [Distributed] make attrs SIMPLE to get serialization generated
* [Distributed] ActorAddress must be Hashable
* [Distributed] Implement transport.actorReady call in local init
* cleanup after rebase
* [Distributed] add availability attributes to all distributed actor code
* cleanup - this fixed some things
* fixing up
* fixing up
* [Distributed] introduce new Distributed module
* [Distributed] diagnose when missing 'import _Distributed'
* [Distributed] make all tests import the module
* more docs on address
* [Distributed] fixup merge issues
* cleanup: remove unnecessary code for now SIMPLE attribute
* fix: fix getActorIsolationOfContext
* [Distributed] cmake: depend on _concurrency module
* fixing tests...
* Revert "another flaky test, help build toolchain"
This reverts commit 83ae6654dd.
* remove xfail
* clenup some IR and SIL tests
* cleanup
* [Distributed] fix cmake test and ScanDependencies/can_import_with_map.swift
* [Distributed] fix flags/build tests
* cleanup: use isDistributed wherever possible
* [Distributed] don't import Dispatch in tests
* dont link distributed in stdlib unittest
* trying always append distributed module
* cleanups
* [Distributed] move all tests to Distributed/ directory
* [lit] try to fix lit test discovery
* [Distributed] update tests after diagnostics for implicit async changed
* [Distributed] Disable remote func tests on Windows for now
* Review cleanups
* [Distributed] fix typo, fixes Concurrency/actor_isolation_objc.swift
* [Distributed] attributes are DistributedOnly (only)
* cleanup
* [Distributed] cleanup: rely on DistributedOnly for guarding the keyword
* Update include/swift/AST/ActorIsolation.h
Co-authored-by: Doug Gregor <dgregor@apple.com>
* introduce isAnyThunk, minor cleanup
* wip
* [Distributed] move some type checking to TypeCheckDistributed.cpp
* [TypeCheckAttr] remove extra debug info
* [Distributed/AutoDiff] fix SILDeclRef creation which caused AutoDiff issue
* cleanups
* [lit] remove json import from lit test suite, not needed after all
* [Distributed] distributed functions only in DistributedActor protocols
* [Distributed] fix flag overlap & build setting
* [Distributed] Simplify noteIsolatedActorMember to not take bool distributed param
* [Distributed] make __isRemote not public
Co-authored-by: Dario Rexin <drexin@apple.com>
Co-authored-by: Kavon Farvardin <kfarvardin@apple.com>
Co-authored-by: Doug Gregor <dgregor@apple.com>
Don't treat `actorIndependent(unsafe)` as its own kind of isolation.
It was only really used as a bring-up hack to break the isolation model,
but shouldn't be in the user model of the language and causes
complications to the implementation.
The Actor protocol is used only to describe actors. When a protocol's
Self type conforms to the actor protocol, any instance declarations on
the protocol or extensions thereof are considered to be actor-isolated
to 'self'.
Because the instance requirements of such a protocol are
actor-isolated to 'self', they can be witnessed by actor-isolated
instance declarations on an actor type. For example:
```swift
protocol P: Actor {
func f() // okay, actor-isolated to self
}
extension P {
func g() { f() } // okay, actor-islated to self
}
actor MyActor: P {
func f() { } // okay, witnesses actor-isolated requirement
}
```
With "unsafe" global actor isolation, we only enforce actor isolation
when interacting with other explicitly-isolated code. This allows some
code to be annotated with, e.g., `@MainActor(unsafe)` so that users
who opt into concurrency get proper diagnostics, but existing code
does not change.
The initializer DeclContext is not a ValueDecl; instead, fish out the
associated VarDecl using other means.
Also while I'm here, fix actor isolation checking in the case where
'self' is explicitly captured in a capture list as well.
Fixes <rdar://problem/72727986>.
[broken] first impl of @actorIndependent in the type checker.
[broken] fixed mistake in my parsing code wrt invalid source range
[broken] found another spot where ActorIndependent needs custom handling
[broken] incomplete set of @actorIndependent(unsafe) tests
updates to ActorIndependentUnsafe
[fixed] add FIXME plus simple handling of IndependentUnsafe context
finished @actorIndependent(unsafe) regression tests
added wip serialization / deserialization test
focus test to just one actor class
round-trip serialize/deserialize test for @actorIndependent
serialize -> deserialize -> serialize -> compare to original
most of doug's comments
addressed robert's comments
fix printing bug; add module printing to regression test
[nfc] update comment for ActorIsolation::IndependentUnsafe
Both overriding declarations and subclasses must have the actor
isolation as their overridden declarations or superclasses,
respectively. Enforce this, ensuring that we're also doing the
appropriate substitutions.
ActorIsolation is rendered as a descriptive phrase before an entity,
e.g, "actor-independent" or "global actor 'UIActor'-isolated" when
used in diagnostics.
Implement propagation rules for global actor constraints, which can come from:
* Enclosing extension or type
* Superclass of a class
* Overridden declaration
* Requirement witnessed by a declaration
* Storage declaration for an accessor
The "privileged" cases for actor instance and global actor isolation
covered the case where the entity itself is within the particular
actor but can be freely used from outside the actor, e.g., because it
is asynchronous or an asynchronous handler. This is the wrong modeling
for the problem, because it's only the first part of that---what the
isolation of the particular entity is---that is needed for most
clients. There will be a different abstraction for that.
Extend the actor isolation checking rules to account for global
actors. For example, a function annotated with a given global actor
can invoke synchronous methods from the same global actor, but not
from a different global actor or a particular actor instance.
Similarly, a method of an (instance) actor that is annotated with a
global actor attribute is not part of the (instance) actor and,
therefore, cannot operate on its actor-isolated state.
Introduce a new attribute `@actorIndependent` that specifies that a
given declaration is considered to be independent of any actor.
Actor-independent declarations do not have access to actor-isolated
state, even when they are declared as instance members of the actor.
On the other hand, actor-independent declarations can be used to
conform to (synchronous) requirements in protocols.
