The NormalProtocolConformance APIs for checking for an explicitly-written
isolation on a conformance were easy to get to, and the real semantic
API was buried in the type checker, leading to some unprincipled
checking. Instead, create a central ProtocolConformance::getIsolation()
to get the (semantic) actor isolation, and let that be the only place
that will access the explicitly-written global actor isolation for a
conformance. Update all call sites appropriately.
With the move to explicitly specifying the global actor for an isolated
conformance, we can now have conformances whose isolation differs from
that of the type, including having actors with global-actor-isolated
conformances. Introduce this generalization to match the proposal, and
update/add tests accordingly.
To pave the way for the new experimental feature which will operate on '@const' attribute and expand the scope of what's currently handled by '_const' without breaking compatibility, for now.
Within the constraint system, introduce a new kind of conformance constraint,
a "nonisolated conforms-to" constraint, which can only be satisfied by
nonisolated conformances. Introduce this constraint instead of the normal
conforms-to constraint whenever the subject type is a type parameter that
has either a `Sendable` or `SendableMetatype` constraint, i.e., when the type
or its values can escape the current isolation domain.
Simplifying into the function expression is wrong,
like `FunctionArgument` this isn't an element that
can be simplified. This also means we don't need
to handle it in `MissingCallFailure`, since we
shouldn't be recording that fix in this case.
Protocol conformances have a handful attributes that can apply to them
directly, including @unchecked (for Sendable), @preconcurrency, and
@retroactive. Generalize this into an option set that we carry around,
so it's a bit easier to add them, as well as reworking the
serialization logic to deal with an arbitrary number of such options.
Use this generality to add support for @unsafe conformances, which are
needed when unsafe witnesses are used to conform to safe requirements.
Implement general support for @unsafe conformances, including
producing a single diagnostic per missing @unsafe that provides a
Fix-It and collects together all of the unsafe witnesses as notes.
FunctionRefKind was originally designed to represent
the handling needed for argument labels on function
references, in which the unapplied and compound cases
are effectively the same. However it has since been
adopted in a bunch of other places where the
spelling of the function reference is entirely
orthogonal to the application level.
Split out the application level from the
"is compound" bit. Should be NFC. I've left some
FIXMEs for non-NFC changes that I'll address in a
follow-up.
Today ParenType is used:
1. As the type of ParenExpr
2. As the payload type of an unlabeled single
associated value enum case (and the type of
ParenPattern).
3. As the type for an `(X)` TypeRepr
For 1, this leads to some odd behavior, e.g the
type of `(5.0 * 5).squareRoot()` is `(Double)`. For
2, we should be checking the arity of the enum case
constructor parameters and the presence of
ParenPattern respectively. Eventually we ought to
consider replacing Paren/TuplePattern with a
PatternList node, similar to ArgumentList.
3 is one case where it could be argued that there's
some utility in preserving the sugar of the type
that the user wrote. However it's really not clear
to me that this is particularly desirable since a
bunch of diagnostic logic is already stripping
ParenTypes. In cases where we care about how the
type was written in source, we really ought to be
consulting the TypeRepr.
Also rename it to `getExplicitReturnStmts` for clarity and have it
take a `SmallVector` out parameter instead as a small optimization and
to discourage use of this new method as an alternative to
`AnyFunctionRef::bodyHasExplicitReturnStmt`.
