[swift-users] withUnsafeMutableBytes is killing me

[Rick Mann]

The following playground reproduces an issue I'm having, in that the code won't compile depending on the content of the closure. In fact, an empty closure is fine, but when I try to call certain things, it's not.

I figure it has something to do with the type inference for inPointer, but I can't figure out what it needs to work.

---------------------------
import Foundation

//	OKAY:

var msg = Data(capacity: 123456)
msg.withUnsafeMutableBytes
{ (inPointer) -> Void in
	foo(inPointer)
}

//error: cannot convert value of type '(_) -> Void' to expected argument type '(UnsafeMutablePointer<_>) -> _'
//{ (inPointer) -> Void in
//^~~~~~~~~~~~~~~~~~~~~~~~

msg.withUnsafeMutableBytes
{ (inPointer) -> Void in
}

//error: cannot convert value of type '(_) -> Void' to expected argument type '(UnsafeMutablePointer<_>) -> _'
//{ (inPointer) -> Void in
//^~~~~~~~~~~~~~~~~~~~~~~~

msg.withUnsafeMutableBytes
{ (inPointer) -> Void in
	var s: Int
	lgs_error(inPointer, 123456, &s)
}

func
foo(_ data: UnsafeMutableRawPointer!)
{
}

func
lgs_error(_ message: UnsafeMutablePointer<Int8>!,
	    _ message_capacity: Int,
	    _ message_size: UnsafeMutablePointer<Int>!) -> Int
{
}
---------------------------


-- 
Rick Mann
rmann at latencyzero.com