The attribute declares that a struct contains "sensitive" data.
It enforces that the contents of such a struct value is zeroed out at the end of its lifetime.
In other words: the content of such a value is not observable in memory after the value's lifetime.
Also add an experimental feature `Sensitive` with which the attribute can be enabled.
This didn't expose any missing imports in the sources of any of the standard
library modules, but that's not entirely surprising. Still, we should have the
feature enabled to test it and prevent regressions from creeping in before the
behavior becomes the default.
Exclude `ExtensionImportVisibility` from module interfaces.
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.
To preserve compatibility with older compilers that do not allow `IsolatedAny`
to be enabled in production compilers, use an alias experimental feature when
building the stdlib (`IsolatedAny2`).
Also, add `@_allowFeatureSuppression(IsolatedAny)` in a couple spots it was
forgotten.
Partially resolves rdar://125138945
The `.swiftinterface` of the standard library must remain compatible with some
older compilers. Unfortunately, some of those older compilers do not allow the
experimental feature `NoncopyableGenerics` to be enabled in production. To
allow the stdlib to build with non-copyable generics enabled and still have the
older compilers consume its interface, we have to use a new experimental
feature identifier that they do not know about.
Partially resolves rdar://125138945
• 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.
allow a more standard way to pass experimental features
from build systems. Also moved other flags relevant to
diagnostics from Frontend options to Lang options.
Ref: rdar://124648653
language feature, and suppress it for `Clock.measure`.
This allows the _Concurrency swiftinterface file to continue building with
compilers that do not support `OptionalIsolatedParameters`. The feature
suppression drops the `isolated` keyword and replaces `#isolation` with
`nil`.
Allow `@_implements` to be expressed in an extension of the protocol in
which the associated type is defined. Use this to uncomment an
intended use of `@_implements` in `Sequence` that could be used to
replace a longstanding hack for associated type inference.
Since this change means that the standard library module interface
won't be accepted by older compilers, introduce a suppressible feature
ssociatedTypeImplements` that covers the use of `@_implements` on type
declarations. This will hide the `@_implements` attribute from older
compilers.
If an extension isn't imported either directly or via a transitive
(`@_exported`) import, its members should not be visible to name
lookup. Implement this behavior behind the experimental flag
ExtensionImportVisibility.
This allows us to remove their explicit `UNINTERESTING_FEATURE` entries for
them FeatureSet.cpp. All of these features have been present in the compiler
since at least Swift 5.8.
NFC.
Our standard conception of suppressible features assumes we should
always suppress the feature if the compiler doesn't support it.
This presumes that there's no harm in suppressing the feature, and
that's a fine assumption for features that are just adding information
or suppressing new diagnostics. Features that are semantically
relevant, maybe even ABI-breaking, are not a good fit for this,
and so instead of reprinting the decl with the feature suppressed,
we just have to hide the decl entirely. The missing middle here
is that it's sometimes useful to be able to adopt a type change
to an existing declaration, and we'd like older compilers to be
able to use the older version of the declaration. Making a type
change this way is, of course, only really acceptable for
@_alwaysEmitIntoClient declarations; but those represent quite a
few declarations that we'd like to be able to refine the types of.
Rather than trying to come up with heuristics based on
@_alwaysEmitIntoClient or other sources of information, this design
just requires the declaration to opt in with a new attribute,
@_allowFeatureSuppress. When a declaration opts in to suppression
for a conditionally-suppressible feature, the printer uses the
suppression serially-print-with-downgraded-options approach;
otherwise it uses the print-only-if-feature-is-available approach.
To maintain source compatibility, SE-0352 does not open existentials
with "self-conforming" type, such as `any Error` or existentials based
on `@objc` protocols. The proposal specified that this behavior would
change in Swift 6. Implement that behavior change, which can be
enabled prior to Swift 6 with the upcoming feature
`ImplicitOpenExistentials` (as documented in SE-0362).
Fixes#70873 / rdar://120902975.
Suppressing this feature doesn't disable the use of new syntax in the
normal way. Instead, it introduces `@rethrows` on the
AsyncIteratorProtocol and AsyncSequence protocols, so that older
compilers can still use the async sequences generated by newer
compilers and standard libraries.
Fixes the rest of rdar://123782658
The name of the `TaskExecutor` protocol was recently changed to remove
underscores after the feature was accepted in Swift Evolution. An implication
of that rename is that the `buildOrdinaryTaskExecutorRef` builtin changed
the type that it expected as the argument. However, the original change
landed in the standard library which as since produced swiftinterfaces
that contain the following inlinable code:
```
@inlinable public init<E>(ordinary executor: __shared E) where E : _Concurrency._TaskExecutor {
#if $BuiltinBuildTaskExecutor
self.executor = Builtin.buildOrdinaryTaskExecutorRef(executor)
#else
fatalError("Swift compiler is incompatible with this SDK version")
#endif
}
```
When a compiler containing the protocol rename attempts to type check the
above inlinable code, it crashes because the builtin is expecting an argument
conforming to `TaskExecutor`, which doesn't exist in this version of the
standard library. The issue is that the current compiler still supports
the `$BuiltinBuildTaskExecutor` feature guard, but the builtin supported
has since changed.
To resolve this issue, we need to stop supporting the `$BuiltinBuildTaskExecutor`
feature guard and introduce a new one that is only supported by compiler versions
that contain the rename. This approach relies on nothing having adopted the
API, otherwise we would need to stage in the rename as a parallel set of APIs,
and only remove the old APIs once nothing is relying on the old _Concurrency
swiftinterfaces.
