`AvailabilityRange` is now being used as a currency type in more of the
compiler, and some of those uses are in permanent `ASTContext` allocations. The
class wraps the `VersionRange` utility, which is itself a wrapper around
`llvm::VersionTuple` with some additional storage for representing sentinel
values. Even though the two sentinel values can be be represented with just a
single bit of additional storage on top of the 16 bytes required to represent
`VersionTuple`, because of alignment requirements the sentinel values end up
bloating the layout of `VersionRange` by many bytes.
To make `AvailabilityRange` and `VersionRange` more efficient to store, we can
instead reserve two unlikely `llvm::VersionTuple` bit patterns as the sentinel
values instead. The values chosen are the same ones LLVM uses to represent
version tuple tombstones and empty keys in a `DenseMap`.
Introduce a constructor that takes an `llvm::VersionTuple` directly, instead of
needing to spell out `VersionRange::allGTE(<tuple>)` which is unnecessarily
verbose.
Introduced `SemanticAvailabilitySpecRequest` to retrieve the semantic spec for
an `AvailabilitySpec`. Add an `isInvalid` bit to `AvailabilitySpec` to track
whether the request failed. Unfortunately, there aren't any easily accessible
spare bits in the layout of `AvailabilitySpec` so it had to be a new field.
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.
Unfortunately, Unsafe*Pointer types do not support non-escapable
pointees so we do not really have anything to map these types to at the
moment. Previously, importing such code resulted in crashes.
rdar://145800679
This makes more efficient use of the permanent memory allocated for
`AvailabilityContext` representations and also fixes a leak that was introduced
in https://github.com/swiftlang/swift/pull/79718 where the small vector for
unavailable domain storage was not being cleaned up on `ASTContext`
deallocation.
Resolves rdar://145929932.
This is the missing check for "rule #1" in the isolated conformances proposal,
which states that an isolated conformance can only be referenced within
the same isolation domain as the conformance. For example, a
main-actor-isolated conformance can only be used within main-actor code.
Choose names that don't imply availability is versioned, since custom
availability will support domains that are version-less (they are simply
available or unavailable).
Introduce `SemanticAvailableAttr` conveniences to compute the deprecated and
obsoleted ranges for an attribute and ensure they remap versions when needed.
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.
