https://github.com/swiftlang/swift/pull/79807 caused a regression in which
`AvailabilityContext` stopped tracking the available version range for the
active platform domain for certain platforms. Fix this by reverting to checking
`AvailabilityDomain::isActive()` to determine when a given platform
`AvailabilityDomain` represents the target platform. The compiler's existing
mapping from target triple to platform domain is incomplete and it's not clear
to me whether fixing that could cause other regressions.
Resolves rdar://147413616.
Regardless of the value specified for `-unavailable-decl-optimization`, decls
that are unavailable in custom availability domains should be treated as always
unreachable at runtime.
Part of rdar://138441307.
Store `CustomAvailabilityDomain` instances in a folding set on `ASTContext`.
This instances of custom domains to be created without needing to cache them in
disparate locations.
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.
Introduce `SemanticAvailableAttr` conveniences to compute the deprecated and
obsoleted ranges for an attribute and ensure they remap versions when needed.
Delay resolution of availability domain identifiers parsed in availability
specifications until type-checking. This allows custom domain specifications to
be written in `if #available` queries.
Implement lookup of availability domains for identifiers on
`AvailabilityDomainOrIdentifier`. Add a bit to that type which represents
whether or not lookup has already been attempted. This allows both
`AvailableAttr` and `AvailabilitySpec` to share a common implementation of
domain lookup.
Using availability domains, reimplement the algorithm that determines whether a
declaration is unavailable at runtime. The new algorithm takes ABI compatible
platforms into account, ensuring that declarations that are available on iOS do
not get treated as unreachable at runtime when compiling for visionOS.
Resolves rdar://116742214.
One to get the active domain for the compilation target and another to get the
ABI compatibility domain for a given domain. The ABI compatibility domain will
be needed for queries that compute whether an unavailable declaration is still
reachable at runtime.
NFC.
* Move `AvailabilitySpec` handling logic to AST, so they can be shared
between libParse and ASTGen
* Requestify '-define-availability' arguments parsing and parse them
with 'SwiftParser' according to the 'ParserASTGen' feature flag
* Implement 'AvailableAttr' generation in ASTGen
Now that most of the compiler tracks availability in terms of
AvailabilityDomain, it's time to do so in AvailabilityContext as well. This
will ensure that the compiler accurately suppresses diagnostics about a decl
being unavailable in an arbitrary domain when the context of the use is already
unavailable in that domain.
With this change, most of the special-casing for the Embedded Swift availability
domain has been removed from the compiler, outside of parsing and interface
printing.
This operation describes the partial ordering with which Availability domains
form a lattice.
As a temporary measure, a containment ordering needs to be specified for the
Swift language, Embedded, and Package Description domains. Without this
ordering, there won't be a way for AvailabilityContext to preserve the
invariant that the unavailable domain of a child context contains the
unavailable domain for the parent. However, once AvailabilityContext is
refactored to represent the status of multiple availability domains
simultaneously, the ordering of these domains relative to each other can be
relaxed.
NFC.
Represent an AvailabilityDomain as a pointer union where one member of the
union is inline storage for built-in domains with known requirements and the
other member of the union is a pointer to an externally allocated domain
definition.
NFC.
It was difficult to preserve the existing, buggy behavior of availability
attribute inference with respect to attributes specifying availability for
non-platform-specific domains. Instead, this change improves attribute merging
by tracking every domain independently, and only merging attributes from the
same domain.
This new attribute iterator returned from the query makes it simpler to
implement algorithms that need access to both the `AvailableAttr *` and its
corresponding `AvailabilityDomain`. This is also work towards making it
possible to return an optional `AvailabilityDomain` from
`Decl::getDomainForAvailableAttr()`.
