On Thu, Feb 22, 2018 at 7:58 AM, Nico Weber <tha...@chromium.org> wrote:
> I have a small personal project where I used to use this. I tried > switching to <optional> instead, but that apparently requires -std=c++17. > With that, things build fine with my locally-built clang, but latest Xcode > clang doesn't accept that flag yet. So I tried -std=c++1z, but latest Xcode > (9.2) doesn't even include the <optional> header yet. So now I have no way > of being able to build my project with both trunk clang and Xcode clang. > Maybe a one-year deprecation period is too short? > Nico -- I'm sorry you were caught out by this. (It's not a huge deal, I have a optional<> implementation in my project for > platforms that don't ship it yet, but things used to be fine on mac until > this change at least. It's also not an important project, I just thought > I'd point out that this makes life more complicated than it would be if the > deletion period was longer.) > Yes, but it also makes life less complicated also. In fact, optional was the poster child for removing stuff from experimental. experimental::optional and std::optional have diverged, and are significantly different today (and only going to get more different in the future) The cost for someone to move to std::optional will never be lower than it is now. (they're only going to become more different). I really didn't (and don't) want to maintain two closely related (but different, and slowly diverging) code bases - and (repeatedly) explain to people the difference between them. As for Apple not shipping std::optional, I too am dismayed by that, but I have no control over that. :-( I don't know when Apple will ship std::optional (they don't share their product plans with me), but it requires an update to libc++.dylib, and in the past they have gone *years* without updating the dylib. Hopefully they will update before LLVM 7 ships in August. -- Marshall
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