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.
We are currently lacking the ability to describe "normal or distributed
actor" with a single protocol in a manner that allows hopping to it,
because `AnyActor` is a marker protocol. Use `Actor` while we sort
this out.
Most clients only want to set one of the two
parameters, split it into `setPattern` and
`setInitContext` (the latter of which now
handles calling `setBinding`).
Use the PatternBindingInitializer context if we
have one. This also uncovered a parser issue where
we would mistakenly create a
PatternBindingInitializer in top-level code after
parsing the initializers.
Introduce a new expression macro that produces an value of type
`(any AnyActor)?` that describes the current actor isolation. This
isolation will be `nil` in non-isolated code, and refer to either the
actor instance of shared global actor in other cases.
This is currently behind the experimental feature flag
OptionalIsolatedParameters.
async for-in loops.
Async iterators are not `Sendable`; they're only meant to be used from
the isolation domain that creates them. But the `next()` method runs on
the generic executor, so calling it from an actor-isolated context passes
non-`Sendable` state across the isolation boundary. `next()` should
inherit the isolation of the caller, but for now, use the opt out.
Start classifying all potential throw sites within a constraint
system and associate them with the nearest enclosing catch node. Then,
determine the thrown error type for a given catch node by taking the
union of the thrown errors at each potential throw site. Use this to
compute the error type thrown from the body of a `do..catch` block
within a closure.
This behavior is limited to the upcoming feature `FullTypedThrows`.
These two requests are effectively doing the same thing to two
different cases within CatchNode. Unify the requests into a single
request, ExplicitCaughtTypeRequest, which operates on a CatchNode.
This also moves the logic for closures with explicitly-specified throws
clauses into the same request, taking it out of the constraint system.
This is currently limited to `InferSendableFromCaptures` feature
but a valid thing to do in general because otherwise it won't be
possible to determine the sendability of the key path type.
Covariant conversions between explicit and contextual/inferred root
types of a key path are simulated through a subtype constraint which
has to be attached to a `KeyPathRoot` element.
This is a very first step in attempt to move some of the logic
from `simplifyKeyPathConstraint` to the inference. This type is
going to be used as an anchor to trigger capability inference.
Teach the constraint solver about the subtyping rule that permits
converting one function type to another when the effective thrown error
type of one is a subtype of the effective thrown error type of the
other, using `any Error` for untyped throws and `Never` for
non-throwing.
With minor other fixes, this allows us to use typed throws for generic
functions that carry a typed error from their arguments through to
themselves, which is in effect a typed `rethrows`:
```swift
func mapArray<T, U, E: Error>(_ array: [T], body: (T) throws(E) -> U)
throws(E) -> [U] {
var resultArray: [U] = .init()
for value in array {
resultArray.append(try body(value))
}
return resultArray
}
```
Doing so fits better into conjunction model which leads to more
granular control over what variables are brought into scope during
`where` clause expression checking.
These changes also remove "one-way bind" flag from "for-in" statement
target.
`lookupConformance` request is not cached and constraint solver
performs a lot of them for the same type (i.e. during disjunction
solving), let's try to cache previously performed requests to
see whether additional memory use is worth the performance benefit.
Use FetchContent to include swift-syntax directly in swift. This can be
thought of as an `add_subdirectory` for a directory outside the root.
The default build directory will be `_deps/swiftsyntax-subbuild/`, though
the modules and shared libraries will be built in `lib/swift/host` by
passing down `SWIFT_HOST_LIBRARIES_DEST_DIR` to avoid copying them as we
were doing previously.
Augment the TypeVarRefCollector such that it
picks up any type variables present in the result
type for a closure DeclContext when visiting a
ReturnStmt. This ensures we correctly handle
if/switch expressions that contain `return`
statements.
rdar://114402042
These allow multi-statement `if`/`switch` expression
branches that can produce a value at the end by
saying `then <expr>`. This is gated behind
`-enable-experimental-feature ThenStatements`
pending evolution discussion.
Move logic from `ConstraintGenerator::visitOverloadedDeclRefExpr`
to pre-check to avoid including macro declarations referenced
without `#`. This means that pre-checking would synthesize
`TypeExpr` in situations when there is a type reference that
is shadowed by a stdlib macro.
Resolves: https://github.com/apple/swift/issues/67815
Resolves: rdar://114796811
Move the contextual type locator onto
ContextualTypeInfo, and consolidate the separate
fields in SyntacticElementTarget into storing a
ContextualTypeInfo. This then lets us plumb down
the locator for the branch contextual type of an
if/switch expression from the initial constraint
generation, rather than introducing it later. This
should be NFC.
Both single- and multi-statement closures now use variable reference
collector to identify variables used in the interpolation body, which
means that it's not longer necessary to connect to the closure explicitly
(if interpolation is contained in one).
