Not the ResultType, you mean, but the input type, right? Yeah, I finally
figured that out, although it doesn't explain another situation I'm
experiencing that I didn't include in the post.
However, that doesn't explain why it can't infer it in the last example.
> On Apr 25, 2017, at 02:58 , Ole Begemann <o...@oleb.net> wrote:
>
> The withUnsafeMutableBytes method has two generic parameters, ResultType and
> ContentType:
>
> mutating func withUnsafeMutableBytes<ResultType, ContentType>(_ body:
> (UnsafeMutablePointer<ContentType>) throws -> ResultType) rethrows ->
> ResultType
>
> In your examples, the type checker can't infer the type of ResultType. You'll
> have to state it explicitly by specifying the type of the closure's argument.
> For example:
>
> msg.withUnsafeMutableBytes {
> (inPointer
> : UnsafeMutablePointer<UInt8>
> ) -> Void in
> // ...
> }
>
>
> On 25.04.2017 10:45, Rick Mann via swift-users wrote:
>> 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
rm...@latencyzero.com
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