* [Swiftify] Emit Mutable[Raw]Span when possible
Previously wrappers would use UnsafeMutable[Raw]Pointer for mutable
pointers, and Span for non-const std::span, to prevent the compiler from
complaining that MutableSpan didn't exist.
Now that MutableSpan has landed we can finally emit MutableSpan without
causing compilation errors. While we had (disabled) support for MutableSpan
syntax already, some unexpected semantic errors required additional
changes:
- Mutable[Raw]Span parameters need to be inout (for mutation)
- inout ~Escapable paramters need explicit lifetime annotations
- MutableSpan cannot be directly bitcast to std::span, because it is
~Copyable, so they need unwrapping to UnsafeMutableBufferPointer
rdar://147883022
* [Swiftify] Wrap if-expressions in Immediately Called Closures
When parameters in swiftified wrapper functions are nullable, we use
separate branches for the nil and nonnil cases, because
`withUnsafeBufferPointer` (and similar) cannot be called on nil.
If-expressions have some limitations on where they are allowed in the
grammar, and cannot be passed as arguments to a function. As such, when
the return value is also swiftified, we get an error when trying to
pass the if-expression to the UnsafeBufferPointer/Span constructor.
While it isn't pretty, the best way forward seems to be by wrapping the
if-expressions in Immediately Called Closures.
The closures have the side-effect of acting as a barrier for 'unsafe':
unsafe keywords outside the closure do not "reach" unsafe expressions
inside the closure. We therefore have to emit "unsafe" where unsafe
expressions are used, rather than just when returning.
rdar://148153063
This feature only exists as a mechanism to suppress the warning introduced in
https://github.com/swiftlang/swift/pull/75378. The RegexParser module, which is
effectively part of the standard library, declares a Swift runtime symbol and
as a result every build of the compiler and stdlib produces warnings which
there are no plans to address. Warnings that are not going to be addressed need
some way of being suppressed, and an experimental features seems like a
reasonable mechanism for this one.
Tweaked diagnostic to use a string instead of a type. Renamed the
feature in `FeatureAvailability.def` (and added the `TaskExecutor`
feature to 6.2). Also fixed the `swift_getActiveExecutor()`
function to return the main executor only when on the main thread.
rdar://141348916
The new generalization sometimes causes a runtime hang that I’m still analyzing. The original declaration should be considered more specific for preexisting use cases, eliminating the source compatibility issue.
The newer clang properly identifies UB on invalid pointer casts. This
was previously being silenced by suppressing the warnings. Adjust the
code to use `std::bit_cast` (or the shim implementation) to avoid the
UB in this code.
Certain dynamic casts cannot work safely with isolated conformances,
regardless of what executor the code runs on. For such cases, reject
all attempts to conform to the type.
