remove requirment on macOS 10.13

[tomerd]

motivation: simplify downstream libraries

changes: use custom ISO8601 decoders on macOS < 10.13

[tomerd]

closes #152

[tomerd]

@helje5

[tomerd]

note strptime is not available via Glibc so this is a bit uglier with #if os blocks

[fabianfett]

Hey @tomerd, I've thought about this a little more... Since strptime is not available through Glibc, we use this really only for macOS before 10.13. In the Swift.package we define the minimum Swift version though with 5.2. I doubt that there is any macOS version out there with 10.12 that runs Swift 5.2, not to speak of a current Xcode version that runs on macOS 10.12 or below, which is the only use case for this.

So maybe we should just preconditionFailure if we are below 10.13? wdyt? Sorry for coming up with this now, after you've already implemented it.

[tomerd]

that sounds okay to me too. @helje5 wdyt?

[helje5]

Either is fine for me. There are some Mac users which tend to stick to older versions, but they are probably not Swift target audience in the first place ;-)

[helje5]

The really interesting question here is why spm decided to stick to 10.10 still, that feels a little weird, but the same reasoning should be applied i guess

[tomerd]

@fabianfett what is your concern about taking this as-is? code bloat/complexity?

[fabianfett]

@fabianfett what is your concern about taking this as-is? code bloat/complexity?

@tomerd I came to the conclusion, when I thought about, how we could test this... Date conversions should be tested by a unit test imho. When thinking about it, I wasn’t sure if there is actually a machine that could fulfill the requirements to run this branch. If there is no machine that the code could be ever run on, we shouldn’t add it because it increases complexity.

[tomerd]

@fabianfett addressed

[fabianfett]

@tomerd leftover?

[tomerd]

good catch, removed

[fabianfett]

Thanks @tomerd LGTM