I think your onto it Philippe but then why is it behaving that way? I updated my earlier script (attached) and added 2 things.
1. print("Start: \(data.startIndex), End: \(data.endIndex), Count:
\(data.count)") after the data.removeFirst(4). 2. The startIndex offset
you suggested.
It no longer crashes. Hooray!
Swift 3.1:
Start: 0, End: 2, Count: 2
Base64: QWE=, String: Aa
Swift 3.2:
Start: 4, End: 6, Count: 2
Base64: QWE=, String: Aa
Oh wait. Woah. That's a really subtle change that has some very real
consequences.
Is this expected and/or documented? Because I certainly would not have
expected that drastic of a change. I'll obviously need to go read a lot
more of the changes between Swift 3.1 and Swift 3.2 if these sorts of
changes are in scope.
On Thu, Aug 24, 2017, at 02:10 PM, Philippe Hausler wrote:
> I see the issue.. the latest version traps (appropriately so).
>
> let str = String(bytes: data[..<2], encoding: .utf8)!
>
> The sub-range of the slice you have is incorrectly indexed. Try this
> out (I am presuming this is what you mean):>
> let str = String(bytes: data[data.startIndex..<(data.startIndex + 2)],
> encoding: .utf8)!>
>> On Aug 24, 2017, at 11:07 AM, Philippe Hausler
>> <phaus...@apple.com> wrote:>>
>> Is there a radar or bugs.swift.org ticket filed on this?
>>
>> I presume because of the import this is a Darwin thing and not a
>> linux thing.>>
>>> On Aug 24, 2017, at 11:05 AM, Michael Gottesman via swift-dev <swift-
>>> d...@swift.org> wrote:>>>
>>>
>>>> On Aug 24, 2017, at 10:47 AM, Ryan Lovelett via swift-dev <swift-
>>>> d...@swift.org> wrote:>>>>
>>>> I've found what I believe is a bug. Though I'm unclear if the bug
>>>> is in>>>> Swift 3.1 or Swift 3.2/4.0. All I can say for sure is the
>>>> behavior is>>>> quite drastically different between the two.
>>>>
>>>> For the code below (and attached):
>>>>
>>>> import Cocoa
>>>>
>>>> var data = Data(bytes: [0x50, 0x4B, 0x01, 0x02, 0x41, 0x61])
>>>> data.removeFirst(4)
>>>> let base64 = data.base64EncodedString()
>>>> let str = String(bytes: data[0..<2], encoding: .utf8)!
>>>> print("Base64: \(base64), String: \(str)")
>>>>
>>>> If I compile and run that with the Swift included in Xcode 8.3.3
>>>> (e.g.,>>>> swift ./data-bug.swift) it outputs: Base64: QWE=, String: Aa.
>>>> Which is>>>> what I expect.
>>>>
>>>> With the Swift that is included with Xcode 9.0 beta 6 (9M214v)
>>>> (e.g.,>>>> swift -swift-version 3 ./data-bug.swift). It performs an illegal
>>>> hardware instruction and crashes. It also does this if I use
>>>> use the>>>> version 4 of the compiler.
>>>>
>>>> Is this a bug? If so where is the bug? Was this always meant to
>>>> not work>>>> and Swift 3.1 just happened to work or is there now an issue
>>>> in the>>>> Swift 3.2 implementation?
>>>
>>> I have not engaged my brain with the particulars of the rest of the
>>> email, but high level question: does this happen without
>>> optimization? Or does it happen only with optimization?>>>
>>> Michael
>>>
>>>> <data-bug.swift>_______________________________________________
>>>> swift-dev mailing list
>>>> swift-...@swift.org
>>>> https://lists.swift.org/mailman/listinfo/swift-dev
>>>
>>> _______________________________________________
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>>> swift-...@swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-dev
data-bug.swift
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