Rather than doing the transform in the parser, and
then potentially undoing it in Sema, move the
entire transform into Sema. This also lets us
unify the logic between function decls and
closures, and allows ASTGen to benefit from it.
Use `inheritsAvailabilityFromPlatform()` to determine whether to suppress
diagnostics about back deployed functions being unavailable. Previously, if the
platform of the `@backDeployed` attribute and the platform of the `@available`
attribute did not match exactly the diagnostic was always suppressed, which was
too permissive.
The old TypeAttributes reprsentation wasn't too bad for a small number of
simple attributes. Unfortunately, the number of attributes has grown over
the years by quite a bit, which makes TypeAttributes fairly bulky even at
just a single SourceLoc per attribute. The bigger problem is that we want
to carry more information than that on some of these attributes, which is
all super ad hoc and awkward. And given that we want to do some things
for each attribute we see, like diagnosing unapplied attributes, the linear
data structure does require a fair amount of extra work.
I switched around the checking logic quite a bit in order to try to fit in
with the new representation better. The most significant change here is the
change to how we handle implicit noescape, where now we're passing the
escaping attribute's presence down in the context instead of resetting the
context anytime we see any attributes at all. This should be cleaner overall.
The source range changes around some of the @escaping checking is really a
sort of bugfix --- the existing code was really jumping from the @ sign
all the way past the autoclosure keyword in a way that I'm not sure always
works and is definitely a little unintentional-feeling.
I tried to make the parser logic more consistent around recognizing these
parameter specifiers; it seems better now, at least.
Allow the use of typed throws for the main functions of `@main` types,
and thread the thrown error through to a new entry point in the library,
`_errorInMainTyped`, which is generic in the thrown error type.
Fixes rdar://121603043.
The reason why I am doing this is before this commit despite the fact that
CapturedValue was only used by TypeLowering, this constructor was exposed to the
entire rest of the compiler. This made it so that other code (like the
AbstractClosureExpr::getIsolationCrossing() that I added in the previous series
of commits) would have to handle that API even though there was nothing to
handle just in case someone added something in the future.
Rather than create such a burden on the rest of the compiler, in this commit, we
instead hide said constructor and make it only accessible from
TypeLowering. This creates a barrier from new uses appearing in AST and make it
reasonable for code in the AST that will never see things from TypeLowering
(like the ACE API I mentioned above) just assert on that case without needing to
worry about additional uses cropping in easily by mistake.
This commit makes it so that we treat values captured by an actor isolated
closure as being transferred to that closure. I also introduced a new diagnostic
for these warnings that puts the main warning on the capture point of the value
so the user is able to see the actual capture that causes the transfer to occur:
```swift
nonisolated func testLocal2() async {
let l = NonSendableKlass()
// This is not safe since we use l later.
self.assumeIsolated { isolatedSelf in
isolatedSelf.ns = l
}
useValue(l) // expected-note {{access here could race}}
}
```
```
test.swift:74:14: warning: main actor-isolated closure captures value of non-Sendable type 'NonSendableKlass' from nonisolated context; later accesses to value could race
useValue(x) // expected-warning {{main actor-isolated closure captures value of non-Sendable type 'NonSendableKlass' from nonisolated context; later accesses to value could race}}
^
test.swift:76:12: note: access here could race
useValue(x) // expected-note {{access here could race}}
^
```
One thing to keep in mind is that if we have a function argument being captured
in this way, we still emit the "call site passes `self`" error. I am going to
begin cleaning that up in the next commit in this PR so that we emit a better
error here. But it makes sense to split these into two separate commits since
they are doing different things.
rdar://121345525
Not quite NFC because apparently the representation bleeds into what's
accepted in some situations where we're supposed to be warning about
conflicts and then making an arbitrary choice. But what we're doing
is nonsense, so we definitely need to break behavior here.
This is setting up for isolated(any) and isolated(caller). I tried
to keep that out of the patch as much as possible, though.
Use an optional isolated parameter to this new `next(_:)` overload to
keep it on the same actor as the caller, and pass `#isolation` when
desugaring the async for..in loop. This keeps async iteration loops on
the same actor, allowing non-Sendable values to be used with many
async sequences.
This couples together several changes to move entirely from
`@rethrows` over to typed throws:
* Use the `Failure` type to determine whether an async for-each loop
will throw, rather than depending on rethrows checking
* Introduce a special carve-out for `rethrows` functions that have a
generic requirement on an `AsyncSequence` or `AsyncIteratorProtocol`,
which uses that requirement's `Failure` type as potentially being part
of the thrown error type. This allows existing generic functions like
the following to continue to work:
func f<S: AsyncSequence>(_: S) rethrows
* Switch SIL generation for the async for-each loop from the prior
`next()` over to the typed-throws version `_nextElement`.
* Remove `@rethrows` from `AsyncSequence` and `AsyncIteratorProtocol`
entirely. We are now fully dependent on typed throws.
Instead of providing a default value for `UnavailableDeclOptimizationMode`,
track it with an optional that defaults to `None`. This way the default
behavior can vary contextually while still honoring an explicit option passed
in on the command line.
Partially resolves rdar://121344690
values.
Teach ActorIsolation that a `nil` isolated argument is statically nonisolated,
and a reference to GlobalActor.shared statically has global actor isolation.
This change also models arbitrary actor instance isolation using VarDecls
when possible, which allows comparing two ActorIsolation values that may
represent different actor instances. Previously, ActorIsolation was
modeled only by storing the nominal actor type and the parameter index,
so the actor isolation value for two different actors was considered
to be equal. Now, the nominal actor type is only used for isolated `self`
in cases where there is no implicit self parameter decl, such as for
stored properties.
a VarDecl or Expr.
This generalization exposed a bug where distributed actor isolation checking
was skipped in some cases, including for the isolated call in `whenLocal`.
The `whenLocal` implementation violated distributed actor isolation because
despite the `__isLocal` dynamic check, the `self` value passed to the `body`
function argument is still not statically local. To workaround this, I
applied the `_local` modifier explicitly to `self` before the call, which
also necessitated allowing `_local` to be written explicitly in the Distributed
library.
It's better to ask SILType if it is MoveOnly than go to the AST type and
ask if it is noncopyable, because some types in SIL do not have a
well-defined notion of conformance in the AST.
