In implicit contexts that are universally unavailable, allow writable key paths
to be formed to properties with setters that are also marked as universally
unavailable. This fixes a regression from the previous commit where the code
synthesized for `@Observable` properties in universally unavailable classes was
rejected by the availability checker.
While the intent behind this functor was noble, it has grown in complexity
considerably over the years, and it seems to be nothing but a source of
crashes in practice. I don't want to deal with it anymore, so I've decided
to just subsume all usages with LookUpConformanceInModule instead.
This patch re-enables diagnostics for unannotated C++ functions or
methods returning `SWIFT_SHARED_REFERENCE` types. These warnings now
fire only **once per source location**, even in the presence of multiple
template instantiations. This avoids diagnostic duplication that was a
key source of noise in the compilation of larger codebases.
These warnings were previously disabled starting in **Swift 6.2** via
[PR-#81411](https://github.com/swiftlang/swift/pull/81411) due to
concerns around false positives and excessive duplication in projects
adopting C++ interop. This patch addresses the duplication issue by
adding source-location-based caching, which ensures that a warning is
emitted only once per source location, even across template
instantiations with different types.
However, the false positive issue remains to be investigated and will be
addressed in a follow-up patch. Until that happens, the warnings are
gated behind a new experimental feature flag:
`WarnUnannotatedReturnOfCxxFrt`. This feature will be enabled by default
only after thorough qualification and testing on large C++ codebases.
rdar://154261051
In the provided test case, the generic signature of the
protocol requirement is
<Self, T where Self == T.A, T: P2>
The conformance requirement `Self: P1` is derived from `T: P2`
and `Self.A: P1` in P1. So given a substitution map
`{ Self := X, T := T }` that replaces T with a concrete type X
and T with a type parameter T, there are two ways to recover a
substituted conformance for `Self: P1`:
- We can apply the substitution map to Self to get X, and look
up conformance of X to P1, to get a concrete conformance.
- We can evaluate the conformance path `(T: P2)(Self.A: P1)`,
to get an abstract conformance.
Both answers are correct, but SILGenModule::emitProtocolWitness()
was assuming it would always get a concrete conformance back.
This was the case until e3c8f423bc,
but then we started returning an abstract conformance. SILGen
would then mangle the protocol witness thunk in a way that was
not sufficiently unique, and as a result, we could miscompile
a program where two witness tables both hit this same scenario.
By using contextual types in the getRequirementToWitnessThunkSubs()
substitution map, we ensure that evaluating the conformance path
against the substitution map produces the same result as performing
the global lookup.
Also, to prevent this from happening again, add a check to SILGen
to guard against emitting two protocol witness thunks with the
same mangled name.
Unfortunately, this is done intentionally as part of some
backward deployment logic for coroutine accessors. There is a
hack to allow duplicate thunks with the same name in this case,
but this should be revisited some day.
Fixes rdar://problem/155624135..
Functions or template instantiations with Obj-C types should always be
behind a macro to make sure the interop header compiles cleanly in C++.
rdar://152836730
Since LayoutPrespecialization has been enabled by default in all compiler
invocations for quite some time, it doesn't make sense for it to be treated as
experimental feature. Make it a baseline feature and remove all the
checks for it from the compiler.
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 MemberImportVisibility is enabled we failed to find certain base
methods from the extensions when said base methods are imported from
C++.
rdar://154887575
Forming an isolated conformance to a SendableMetatype-inherting
protocol opens up a soundness hole any time the conformance is used.
Reword the recently-introduced diagnostic for this case and promote it
to an error (except when it's preconcurrency).
Fixes rdar://154808002.
Generalize SILGen for `if #available` checks by delegating the determination of
the query function and its arguments to `AvailabilityQuery`. Update SILGen for
`@backDeployed` thunks to use the same infrastructure.
NFC.
This is an accepted spelling for the attribute. This commit
also renames the feature flag from `ExtensibleAttribute` to
`NonexhaustiveAttribute` to match the spelling of the attribute.
