When attempting to compile Swift 2 code (or any Swift code using the
Swift 2 names) in Swift 3, the compiler diagnostics are often entirely
useless because the names have changed radically enough that one
generally gets "no member named 'foo'" errors rather than a helpful
"'foo' was renamed to 'bar'" error. This makes for a very poor user
experience when (e.g.) trying to move Swift 2 code forward to Swift 3.
To improve the experience, when the Swift 2 and Swift 3 names of an
API differ, the Clang importer will produce a "stub" declaration that
matches the Swift 2 API. That stub will be marked with a synthesized
attribute
@available(unavailable, renamed: "the-swift-3-name")
that enables better diagnostics (e.g., "'foo' is unavailable: renamed
to 'bar') along with Fix-Its (courtesy of @jrose-apple's recent work)
that fix the Swift 2 code to compile in Swift 3.
This change addresses much of rdar://problem/25309323 (concerning QoI
of Swift 2 code compiled with a Swift 3 compiler), but some cleanup
remains.
The Clang importer implicitly synthesizes @discardableResult for
nearly all imported functions. Printing this attribute in the
generated interface leads to a lot of noise. Mark it as implicit so we
don't print it.
There's an odd, and unknown bug in the Clang Importer where we seem to
fail a Clang lookup of NSObject the very first time we try. While I'm
still diagnosing this, un-block SILGen work.
Introduce abstraction patterns for curried C-functions-as-methods for type lowering, and plumb the "foreign self parameter index" through call emission so that we emit the "self" parameter in the right position. This gets us handling C functions imported as methods with explicit swift_name attributes in simple, fully-applied cases. There's still more work to be done for properties, partial applications, and initializers introduced by extensions.
Expands support for inference of computed properties, whether instance
or static, to include get-only. Adds test cases for both inference and
manual annotation for static computed properties.
When a global function is determined to be a lone getter or a
getter/setter pair, import it as a property. Handle global, instance,
and static properties.
As part of this, generalize importAsMethod to also handle static
methods and map pointer-to-non-const arguments to 'mutating' methods.
When printing the interface for a (sub)module, make sure that we only
print those extensions that were created to hold that submodule's
globals that were imported as members.
Print module functionality hooked up to import global functions a
methods, if dictated by the swift_name attribute. Test case included.
No SILGen support yet.
Wire up the extensions created when importing globals-as-members via
the same mechanisms we use for Objective-C categories, e.g.,
implementing loadAllExtensions() to find the extensions and lazily
loading their members via the member loader. Addresses most of my
comments on the way extensions were wired in.
Extend our testing for importing globals as members to two different
submodules, so we can see the separation of extensions.
As part of this, fold getOrCreateExtension into importDeclContextOf.
Specially identify and import-as-init. Module printing works, but not
SILGen.
This will break any SILGen tests over a file that imports a module
with an import-as-init name, as newly imported inits are not hooked up
correctly.
When importing as a member, we want a single unique extension
declaration per type per Clang submodule. This adds the mapping,
switches import-as-member VarDecl importing to use it, and forces the
created extensions to show up.
