It is no longer necessary to produce `.swiftinterface` files the support older
compilers that lack support for the NoncopyableGenerics feature. Cleaning this
up makes the stdlib `.swiftinterface` far more readable.
Out of an abundance of caution, we:
1. Left in parsing support for transferring but internally made it rely on the
internals of sending.
2. Added a warning to tell people that transferring was going to
be removed very soon.
Now that we have given people some time, remove support for parsing
transferring.
rdar://130253724
Although I don't plan to bring over new assertions wholesale
into the current qualification branch, it's entirely possible
that various minor changes in main will use the new assertions;
having this basic support in the release branch will simplify that.
(This is why I'm adding the includes as a separate pass from
rewriting the individual assertions)
The handling of multi-basic-block control flow in `defer` blocks looks like it
was left incomplete and completely untested; I fixed a few obvious problems but
it still completely lacks any analysis of conditional reinitializations. For now,
change it to treat attempted reinitializations as uses-after-consumes so we raise
reliable errors now instead of emitting code that causes memory corruption at
runtime. Fixes rdar://129303198.
A few things:
1. Internally except for in the parser and the clang importer, we only represent
'sending'. This means that it will be easy to remove 'transferring' once enough
time has passed.
2. I included a warning that suggested to the user to change 'transferring' ->
'sending'.
3. I duplicated the parsing diagnostics for 'sending' so both will still get
different sets of diagnostics for parsing issues... but anywhere below parsing,
I have just changed 'transferring' to 'sending' since transferring isn't
represented at those lower levels.
4. Since SendingArgsAndResults is always enabled when TransferringArgsAndResults
is enabled (NOTE not vis-a-versa), we know that we can always parse sending. So
we import "transferring" as "sending". This means that even if one marks a
function with "transferring", the compiler will guard it behind a
SendingArgsAndResults -D flag and in the imported header print out sending.
rdar://128216574
We still only parse transferring... but this sets us up for adding the new
'sending' syntax by first validating that this internal change does not mess up
the current transferring impl since we want both to keep working for now.
rdar://128216574
The standard library defines
```
protocol BitwiseCopyable {}
typealias _BitwiseCopyable = BitwiseCopyable
```
For current compilers, `BitwiseCopyable` is a "known protocol".
For older compilers, it is not; instead `_BitwiseCopyable` is. So
print the following into the swiftinterface for those older compilers:
```
protocol _BitwiseCopyable {}
typealias BitwiseCopyable = _BitwiseCopyable
```
rdar://127755503
With the generalization of Optional to support noncopyable types, our
feature-guarding in swiftinterface files would double-print functions
that simply refer to the Optional type.
Since NoncopyableGenerics is a suppressible feature, by default
a second version of Optional and UnsafePointer are emitted into
swiftinterface files, where the ~Copyable generalization is stripped
away.
We can rely on that to avoid double-printing the function, if the types
substituted for the generic parameters are all Copyable.
We need a bit more checking for when
`@_disallowFeatureSuppression(NoncopyableGenerics)` is used, since this
trick relies on there always being a definition of the type we refer to,
whether the feature is enabled or not.
resolves rdar://127389991
upcoming feature.
The bespoke flag still works as a way to enable the `NonfrozenEnumExhaustivity`
upcoming feature. `NonfrozenEnumExhaustivity` is enabled by default in the
Swift 6 language mode as errors, and enabled by default in the Swift 5 language
mode as warnings.
Resilence support will require changes to the Objective-C runtime to expand support for metadata initialization functions. Add a separate experimental feature flag to help with staging that support in, and modify diagnostics to not suggest increasing the minimum deployment target for now.
