Availability version remapping currently only applies to code built for
visionOS. We plan to introduce more platform kinds and standalone availability
domains that will require version remapping, though, so it's time to
rearchitect and simplify the code to make it easier to generalize.
`AvailabilityDomain` is now responsible for version remapping and much of the
previously duplicated utilities have been consolidated.
Add support for the `Swift` availability domain, which represents availability
with respect to the Swift runtime. Use of this domain is restricted by the
experimental feature `SwiftRuntimeAvailability`.
`AvailabilityDomain` is a pointer union over `CustomAvailabilityDomain` and an
opaque pointer-like 24-bit value, which means the number of spare bits in an
`AvailabilityDomain` representation is one fewer than a
`CustomAvailabilityDomain` pointer. Other structures in the compiler rely on
there being at least 2 spare bits in `AvailabilityDomain`, though, which was
not the case when building for a 32 bit architecture. To ensure there are
enough spare bits, always align `CustomAvailabilityDomain` to 8 bytes, the same
as many AST data structures.
A "permanently enabled" availability domain is one that has been declared
always available and is also simultaneously has either an attribute that
makes it deprecated or universally unavailable.
Emit fix-its that remove (or update) `@available` attributes that restrict
availability in a permanently enabled domain. Also, emit warnings about
`if #available` queries that always return true because they check a
permanently enabled domain.
Resolves rdar://157601761.
An always enabled availability domain is implicitly available in all contexts,
so uses of declarations that are marked as `@available` in the domain are never
rejected. This is useful for an availability domain representing a feature flag
that has become permanently enabled.
Partially resolves rdar://157593409.
Cache the result of turning a `ValueDecl` into an `AvailabilityDomain`. Use
split caching to make the common case of the decl not representing an
availability domain efficient.
NFC.
Use these queries to replace some duplicated code. Also, move the
`attr_inlinable_available.swift` test to the `Availability` sub-directory since
the test has more to do with availability checking than it has to do
specifically with the `@inlinable` attr.
When importing custom availability domains with dynamic predicates from Clang
modules, synthesize predicate functions for `if #available` queries and call
them when generating SIL.
Resolves rdar://138441312.
When compiling for visionOS, iOS availability attributes are remapped into the
visionOS availability domain automatically. While the version remapping was
being performed correctly, there was a regression that caused the platform name
to be printed incorrectly in many diagnostics. Whenever an iOS version is
remapped to a visionOS version, availability diagnostics will now present
those versions as visionOS versions instead of iOS versions.
Resolves rdar://146293165.
When serializing `@available` attributes, if the attribute applies to a custom
domain include enough information to deserialize the reference to that domain.
Resolves rdar://138441265.
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.
