[swift-users] Linux - Calendar date(byAdding:to:wrappingComponents:) returns nil when it shouldn't?

Alex Blewitt alblue at apple.com
Wed Oct 5 10:48:34 CDT 2016

> On 4 Oct 2016, at 20:10, Jason Ji via swift-users <swift-users at swift.org> wrote:
> Hello,
> I'm having an issue with (NS)Calendar on Linux which I think is a bug, but I just wanted to check first if it was just me or if this is indeed a bug. I've filed a bug report here, just in case: https://bugs.swift.org/browse/SR-2846 <https://bugs.swift.org/browse/SR-2846>
> In short, Calendar has a method date(byAdding:to:wrappingComponents:) which returns a new date which is the result of date arithmetic on the passed-in date. It works fine on El Capitan, but doesn't seem to work properly on Ubuntu 14.04. Below is some sample code:
> import Foundation
> let today = Date()
> let diffComponents = DateComponents(day: -1)
> let newDate = Calendar.current.date(byAdding: diffComponents, to: today)		//returns nil
> I've tried this in the swift REPL on Ubuntu 14.04 with both Swift 3.0-RELEASE, and the latest snapshot (October 2).
> If anyone else could try this out as a sanity check for me, that would be great - I'd be happy to be embarrassed that I've done something wrong.

It's worth explicitly specifying a calendar (so that it rules out any environmental setup) -- for example, Calendar(identifier:.gregorian). However, I see 'nil' as well as the return result for this operation, so it could be a bug.


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