Generic Objective-C classes with this annotation will be imported as
non-generic in Swift. The Swift 3 behavior hardcoded a certain set of
class /hierarchies/ as permanently non-generic, and this is preserved
in Swift 3 mode.
Actually using this API note in a versioned way (as opposed to just
marking the class non-generic in all language versions) will cause
horrible source compatibility problems in the mix-and-match cases,
where Swift 3 code presents a non-generic type that Swift 4 expects to
be generic or vice versa. Fixes for this will come later; right now
it's more important to add support for the feature at all.
To avoid unwanted changes in Swift 4, this commit also adds API notes
to make any existing classes in the previously-hardcoded set continue
to import as non-generic even in Swift 4. The difference is that
/subclasses/ of these classes may come in as generic. (If we want to
make a change here, that can be a separate commit.)
rdar://problem/31226414 (Swift side of rdar://problem/28455962)
If a top-level declaration is imported as a member in Swift 4 but not
in Swift 3, it would still show up in the lookup table for the
containing type in Swift 3 mode. We would import it, and then try to
add the top-level declaration to the containing type.
I'm about to redo this anyway so that the versioned stub will show up
(the one for the Swift 4 name) but this is the narrow fix that avoids
the assertion failure we were seeing.
rdar://problem/31161489
Unlike values, we can't import multiple copies of types under
different names and get good results. Instead, we make a typealias
that points back to the original type. Make sure this typealias is
flagged with whatever version is appropriate, rather than always using
"Swift 2".
When a C declaration is marked unavailable with a replacement, we look
for the replacement to see how it would be imported into Swift. Make
sure we do that with respect to the active language version.
This doesn't actually have any effect yet, but if we start importing
both Swift 3 and Swift 4 versions of protocol requirements and the
non-active one is unavailable, we might mistakenly mark the protocol
un-implementable even when the requirements that are needed are all
there. (Hopefully we would never make a protocol /less/ available in a
newer release, of course.) The test case is designed to catch that.
When importing a property as accessor methods (rather than as a
property), we were still importing the type of the accessor methods as
if they were Swift getters and setters of a property, which
(necessarily) homogenizes the types. The homogenization is unnecessary
when importing as accessor methods, because the methods are
independent, so just import the accessor method types as if the
property did not exist. This is particularly useful for maintaining
Swift 3 source compatibility for cases where Swift 4 turns a
getter/setter pair into a null_resettable property.
Fixes rdar://problem/30075571.
Swift side of this new flag. This allows Objective-C framework authors
to replace a pair of methods by properties without breaking source
compatibility. This is especially important for class properties,
which were only introduced last year.
Still to come: importing the accessors even when this flag isn't set,
in order to provide better QoI when migrating from a method interface
to a property interface.
Part of rdar://problem/28455962
Clang now accepts an option -fapinotes-swift-version=XX that describes
which Swift version to use when applying API notes to the Clang
AST. Pass this option down to Clang based on the Swift major version
number (e.g., 3 or 4), allowing API notes to introduce
Swift-version-specific behavior.
Fixes rdar://problem/28617631.
Enable newly-introduced Clang functionality to load API notes stored
alongside the headers for a module or, for a framework, in an APINotes
subdirectory within the framework. Fixes rdar://problem/28455644.
