Update for SE-0107: UnsafeRawPointer
This adds a "mutating" initialize to UnsafePointer to make
Immutable -> Mutable conversions explicit.
These are quick fixes to stdlib, overlays, and test cases that are necessary
in order to remove arbitrary UnsafePointer conversions.
Many cases can be expressed better up by reworking the surrounding
code, but we first need a working starting point.
As proposed by SE-0107: UnsafeRawPointer:
https://github.com/apple/swift-evolution/blob/master/proposals/0107-unsaferawpointer.md#cstring-conversion
Adds String.init(cString: UnsafePointer<UInt8>)
Adds String.nulTerminatedUTF8CString: ContiguousArray<CChar>
This is necessary for eliminating UnsafePointer conversion. Such
conversion is extremely common for interoperability between Swift
strings and C strings to bridge the difference between CChar and
UTF8.CodeUnit. The standard library does not provide any convenient
utilities for converting between the differently typed
buffers. These APIs will handle the simplest cases involving C
interoperability. More convenience can be added later.
As proposed in SE-0107: UnsafeRawPointer:
Rename 'init(allocatingCapacity:)' to 'UnsafeMutablePointer.allocate(capacity:)'
Rename 'deallocateCapacity' to 'deallocate(capacity:)'
`allocate` should not be an initializer. It's primary function is to allocate
memory, not initialize a pointer.
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.
