[SR-2468] Add a predefined enum for a deallocator that matches UnsafeMutableRawPointer.allocate in Data(bytesNoCopy:count:deallocator)

[swift-ci]

Previous ID	SR-2468
Radar	radar://27987799
Original Reporter	slizeray (JIRA User)
Type	Improvement

Additional Detail from JIRA

Votes	0
Component/s	Foundation
Labels	Improvement, SDKOverlay
Assignee	None
Priority	Medium

md5: 350bc083a2e707af5a997f7350836230

Issue Description:

At the moment we must define a custom allocator for the following code:

let retPointer = UnsafeMutableRawPointer.allocate(bytes: size, alignedTo: MemoryLayout<UInt8>.alignment)

let d = Data(bytesNoCopy: retPointer, count: size, deallocator: .custom({ (ptr, size) in
ptr.deallocate(bytes: size, alignedTo: 1)
}))

It would be nice to have a predefined enum for a deallocator that matches UnsafeMutableRawPointer.allocate

[swift-ci]

Comment by Stéphane Lizeray (JIRA)

@parkera @atrick here is the feature request we have been discussing about by mail in the swift-users mailing list

[atrick]

Thanks for filing this.

The same predefined deallocator should work with memory allocated from either:

UnsafeMutablePointer<T>.allocate(capacity:)

or

UnsafeMutableRawPointer.allocate(bytes: alignedTo:)

It just needs to store the size and alignment and invoke:

UnsafeMutableRawPointer.deallocate(bytes: alignedTo:)