This change introduces a new compilation target platform to the Swift compiler - visionOS.
- Changes to the compiler build infrastrucuture to support building compiler-adjacent artifacts and test suites for the new target.
- Addition of the new platform kind definition.
- Support for the new platform in language constructs such as compile-time availability annotations or runtime OS version queries.
- Utilities to read out Darwin platform SDK info containing platform mapping data.
- Utilities to support re-mapping availability annotations from iOS to visionOS (e.g. 'updateIntroducedPlatformForFallback', 'updateDeprecatedPlatformForFallback', 'updateObsoletedPlatformForFallback').
- Additional tests exercising platform-specific availability handling and availability re-mapping fallback code-path.
- Changes to existing test suite to accomodate the new platform.
The model for associated types hasn't been fully worked-out for
noncopyable generics, but there is some support already that is being
used by the stdlib for an internal-only (and rather cursed) protocol
`_Pointer` to support `UnsafePointer`, etc.
This patch gates the existing experimental support for associated types
behind a feature flag. This flag doesn't emit feature-guards in
interfaces, since support for it is tied closely to NoncopyableGenerics
and has been there from its early days.
Emit metadata for runtime checks of conformances of associated types to
invertible protocols, e.g., `T.Assoc: Copyable`. This allows us to
correctly handle, e.g., dynamic casting involving conditional
conformances that have such constraints.
The model we use here is to emit an invertible-protocol constraint
that leaves only the specific bit clear in the invertible protocol
set.
• ObjCImplementation controls @implementation on extensions
• CImplementation controls @implementation and @_objcImplementation on cdecl functions
Why the difference between them? Because `@_objcImplementation extension` has already been adopted pretty widely, while `@_objcImplementation @_cdecl` is very new.
Form a set of suppressed protocols for a function type based on
the extended flags (where future compilers can start recording
suppressible protocols) and the existing "noescape" bit. Compare
that against the "ignored" suppressible protocol requirements, as we
do for other types.
This involves a behavior change if any client has managed to evade the
static checking for noescape function types, but it's unlikely that
existing code has done so (and it was unsafe anyway).
Add more runtime support for checking suppressible protocol requirements:
* Parameter packs now check all of the arguments appropriately
* Most structural types now implement checking (these are hard to test).
Introduce metadata and runtime support for describing conformances to
"suppressible" protocols such as `Copyable`. The metadata changes occur
in several different places:
* Context descriptors gain a flag bit to indicate when the type itself has
suppressed one or more suppressible protocols (e.g., it is `~Copyable`).
When the bit is set, the context will have a trailing
`SuppressibleProtocolSet`, a 16-bit bitfield that records one bit for
each suppressed protocol. Types with no suppressed conformances will
leave the bit unset (so the metadata is unchanged), and older runtimes
don't look at the bit, so they will ignore the extra data.
* Generic context descriptors gain a flag bit to indicate when the type
has conditional conformances to suppressible protocols. When set,
there will be trailing metadata containing another
`SuppressibleProtocolSet` (a subset of the one in the main context
descriptor) indicating which suppressible protocols have conditional
conformances, followed by the actual lists of generic requirements
for each of the conditional conformances. Again, if there are no
conditional conformances to suppressible protocols, the bit won't be
set. Old runtimes ignore the bit and any trailing metadata.
* Generic requirements get a new "kind", which provides an ignored
protocol set (another `SuppressibleProtocolSet`) stating which
suppressible protocols should *not* be checked for the subject type
of the generic requirement. For example, this encodes a requirement
like `T: ~Copyable`. These generic requirements can occur anywhere
that there is a generic requirement list, e.g., conditional
conformances and extended existentials. Older runtimes handle unknown
generic requirement kinds by stating that the requirement isn't
satisfied.
Extend the runtime to perform checking of the suppressible
conformances on generic arguments as part of checking generic
requirements. This checking follows the defaults of the language, which
is that every generic argument must conform to each of the suppressible
protocols unless there is an explicit generic requirement that states
which suppressible protocols to ignore. Thus, a generic parameter list
`<T, Y where T: ~Escapable>` will check that `T` is `Copyable` but
not that it is `Escapable`, and check that `U` is both `Copyable` and
`Escapable`. To implement this, we collect the ignored protocol sets
from these suppressed requirements while processing the generic
requirements, then check all of the generic arguments against any
conformances not suppressed.
Answering the actual question "does `X` conform to `Copyable`?" (for
any suppressible protocol) looks at the context descriptor metadata to
answer the question, e.g.,
1. If there is no "suppressed protocol set", then the type conforms.
This covers types that haven't suppressed any conformances, including
all types that predate noncopyable generics.
2. If the suppressed protocol set doesn't contain `Copyable`, then the
type conforms.
3. If the type is generic and has a conditional conformance to
`Copyable`, evaluate the generic requirements for that conditional
conformance to answer whether it conforms.
The procedure above handles the bits of a `SuppressibleProtocolSet`
opaquely, with no mapping down to specific protocols. Therefore, the
same implementation will work even with future suppressible protocols,
including back deployment.
The end result of this is that we can dynamically evaluate conditional
conformances to protocols that depend on conformances to suppressible
protocols.
Implements rdar://123466649.
A `try_apply` with indirect out arguments is only a def for those arguments on
the success path. Model this by sinking the def-ness of the instruction into the
success branch of the try_apply, and introducing a new `DeadToLiveEdge` mode for
block liveness which stops propagation of use-before-def conditions into the
block that introduced the def. Fixes rdar://118567869.
The test emits a different function based on deployment target. And
that different function results in different behavior. But some
platforms don't have old enough deployment targets to use the function
for older platforms. So just target newer platforms.
rdar://124700033
Previously, in place of the layout of an aggregate which consisted of
exactly one field, the layout of that one field would be used. This is
incorrect in the case that the aggregate is noncopyable but the field is
not. Here, it's checked that the move-only-ness of the field matches
the move-only-ness of the aggregate.
rdar://123197751
Fix overflow detection on unowned refcounts so that we create a side table when incrementing from 126. Implement strong refcount overflow to the side table.
The unowned refcount is never supposed to be 127, because that (sometimes) represents the immortal refcount. We attempt to detect that by checking newValue == Offsets::UnownedRefCountMask, but the mask is shifted so that condition is never true. We managed to hit the side table case when incrementing from 127, because it looks like the immortal case. But that broke when we fixed immortal side table initialization in b41079a8f54ae2d61c68cdda46c74232084af020. With that change, we now create an immortal side table when overflowing the unowned refcount, then try to increment the unowned refcount in that immortal side table, which traps.
rdar://123788910
