This ensures that opened archetypes always inherit any outer generic parameters from the context in which they reside. This matters because class bounds may bind generic parameters from these outer contexts, and without the outer context you can wind up with ill-formed generic environments like
<τ_0_0, where τ_0_0 : C<T>, τ_0_0 : P>
Where T is otherwise unbound because there is no entry for it among the generic parameters of the environment's associated generic signature.
Augment the constraint solver to fallback to implicit `~=` application
when member couldn't be found for `EnumElement` patterns because
`case` statement should be able to match enum member directly, as well
as through an implicit `~=` operator application.
We used to incorrectly forward inout paramters in the thunk for both template paramters that aren't used in the signature and in the thunk for dependent types as Any.
Now this works in the simple case. We'll need to do something more complicated when we have an `inout Any` for dependent types because we will need to somehow cast without copying. This will probably require synthesising the SIL of the thunk manually.
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.
When calling a generic function with an argument of existential type,
implicitly "open" the existential type into a concrete archetype, which
can then be bound to the generic type. This extends the implicit
opening that is performed when accessing a member of an existential
type from the "self" parameter to all parameters. For example:
func unsafeFirst<C: Collection>(_ c: C) -> C.Element { c.first! }
func g(c: any Collection) {
unsafeFirst(c) // currently an error
// with this change, succeeds and produces an 'Any'
}
This avoids many common sources of errors of the form
protocol 'P' as a type cannot conform to the protocol itself
which come from calling generic functions with an existential, and
allows another way "out" if one has an existention and needs to treat
it generically.
This feature is behind a frontend flag
`-enable-experimental-opened-existential-types`.
Dependent types are going to be very hard to support, especially in complex cases. This PR adds a workaround that people can use: `Any`. This requires manual type casting, but it does work.
Re-write the parameter list to use (U)Int if that was one of the substituted parameters. This is required because Windows will incorrectly map Int -> long long -> Int64.
Clients can explicitly ask for the opened existential type on the archetype's generic environment,
or use `getExistentialType` to obtain a specific archetype's upper bounds.
Situations like `T(...) { ... }` where `T` is a callable type
and trailing closure belongs to `.callAsFunction` should be
rewritten as `T.init().callAsFunction { ... }`.
`shouldCoerceToContextualType` used `solution.getType(ASTNode)`
which returns a type that has type variables in it. To properly
check whether result type needs a coercion it has to be resolved
first which is done via `solution.getResultType(ASTNode)`.
Resolves: rdar://88285682
Opened archetypes can be created in the constraint system, and the
existential type it wraps can contain type variables. This can happen
when the existential type is inferred through a typealias inside a
generic type, and a member reference whose base is the opened existential
gets bound before binding the generic arguments of the parent type.
However, simplifying opened archetypes to replace type variables is
not yet supported, which leads to type variables escaping the constraint
system. We can support cases where the underlying existential type doesn't
depend on the type variables by canonicalizing it when opening the
existential. Cases where the underlying type requires resolved generic
arguments are still unsupported for now.
Nested archetypes are represented by their base archetype kinds (primary,
opened, or opaque type) with an interface type that is a nested type,
as represented by a DependentMemberType. This provides a more uniform
representation of archetypes throughout the frontend.
We were never setting these opaque type substitutions, but code
generation was silently failing. Now we assert, so move the code into
the proper common location so we always set opaque type substitutions
on properties.
Fixes rdar://86800325.
Opaque opaque types and record them within the "opened types" of the
constraint system, then use that information to compute the set of
substitutions needed for the opaque type declaration using the normal
mechanism of the constraint solver. Record these substitutions within
the underlying-to-opaque conversion.
Use the recorded substitutions in the underlying-to-opaque conversion
to set the underlying substitutions for the opaque type declaration
itself, rather than reconstructing the substitutions in an ad hoc manner
that does not account for structural opaque result types.
Instead of checking the frontend flag directly, let's use dedicated
method on a constraint system to determine whether closure did
participate in inference or not.
