Build fails with: class template optional is only available with C++17 or later. about windows-appsample-xaml-hosting

[bmitchell287]

Thanks to both of you. We're looking into the issue and the PR. We'll follow up shortly.

[MarkIngramUK]

I've put in a PR to fix this #2

[bmitchell287]

@MarkIngramUK - Hi Mark, just to confirm, were you also hitting this issue prior to any adjustments? We just tried on 15.8.6 but we're not able to reproduce.

[MarkIngramUK]

@MarkIngramUK - Hi Mark, just to confirm, were you also hitting this issue prior to any adjustments? We just tried on 15.8.6 but we're not able to reproduce.

Hi @bmitchell287 , yes, I cloned the repo two days and experienced the same issues. I believe I had 15.8.6 installed at the time (along with Windows 1809).

[MarkIngramUK]

@bmitchell287 , I've just noticed I only changed the project config settings for the x64 builds (I can update the PR tomorrow) - are you guys trying to repro via Win32 config?

[JoshuaPartlow]

@MarkIngramUK - Hi Mark, we've tried repro'ing in a number of ways (including both configs) with no luck. Not quite sure why we're not seeing the same errors as you both. We'll keep trying in the morning though to see if we can determine what's different.

@rido-min - Hi Ricardo, When you updated to add the /std:c++17 flag, did you happen to notice what was showing in your project properties prior to that? If you have a moment, would you also be able to verify if Mark's suggested fix of adding the WindowsApp.lib dependency fixes things for you as well? Some details on doing so are here or in Mark's pull request itself.

[MarkIngramUK]

@JoshuaPartlow @bmitchell287 - I think I've just worked out why this was failing. I've just checked out the commit before my fixes, did a clean and build, and everything worked fine. The only thing that has changed between when I first built, and retrying it today is, I have installed the C++/WinRT VSIX extension. I assume you guys also have the VSIX installed? And I bet @rido-min probably doesn't.

[JoshuaPartlow]

@MarkIngramUK - Hi Mark, that's definitely what it is, we were able to confirm on our end. We missed including the VSIX download in the README info as a prerequisite as we've had it installed for awhile. We were able to validate what you both were seeing. Thanks so much for helping us with your PR and support for the project! We'll merge in your PR shortly and update the README. As an fyi, there's now also a NuGet package that provides build support for C++ /WinRT. We'll get that added shortly, but you can see details about how that works along with the VSIX here.

@rido-min - Hi Ricardo, I believe the information here should address your issue. If you install the VSIX and are still having issues after pulling the latest, please let us know.

[rido-min]

Fixed