Clean up a few general patterns that are now obviated by canImport
This aligns more generally with the cleanup that the Swift Package
Manager has already done in their automated XCTest-plumbing tool in
apple/swift-package-manager#1826.
We're now correctly checking for inheritance, adding @objc methods,
and adding @objc protocols for both CF types and objc_runtime_visible
classes (those without visible symbols). The latter is used for some
of the types in Dispatch, which has exposed some of the classes that
were considered implementation details on past OSs.
We still don't properly implement using 'as?' to check conformance to
a Swift protocol for a CF or objc_runtime_visible type, but we can do
that later.
rdar://problem/26850367
Implements SE-0055: https://github.com/apple/swift-evolution/blob/master/proposals/0055-optional-unsafe-pointers.md
- Add NULL as an extra inhabitant of Builtin.RawPointer (currently
hardcoded to 0 rather than being target-dependent).
- Import non-object pointers as Optional/IUO when nullable/null_unspecified
(like everything else).
- Change the type checker's *-to-pointer conversions to handle a layer of
optional.
- Use 'AutoreleasingUnsafeMutablePointer<NSError?>?' as the type of error
parameters exported to Objective-C.
- Drop NilLiteralConvertible conformance for all pointer types.
- Update the standard library and then all the tests.
I've decided to leave this commit only updating existing tests; any new
tests will come in the following commits. (That may mean some additional
implementation work to follow.)
The other major piece that's missing here is migration. I'm hoping we get
a lot of that with Swift 1.1's work for optional object references, but
I still need to investigate.
Introduces CoreGraphics.apinotes, in which we enable the
import-as-member inference system. Additionally, include some explicit
SwiftNames, for when inference doesn't produce the right result, and
to aid compatibility with the overlays.
Refactors many of the trivial overlays out, shrinking the
CoreGraphics.swift overlay by over half. Updates in-tree test
cases. The names we currently have will be highly in flux for a while,
and are likely to change frequently over the near term.
There are a few remaining known bugs that are worked around by
apinotes entries.
