Use throw rather than abort() for guid parse failures

[dfields-msft]

Make winrt::guid("...") more useful at runtime by throwing on failure instead of aborting the program. See #991

[dfields-msft]

@kennykerr does a successful run of "C++ for WinRT Xlang Internal Build" include the Clang validation you were asking for?

[kennykerr]

Thanks! Please add a test that verifies this works. At a glance, this won't compile.

[kennykerr]

Yes, you can either validate it locally or run the build once a test has been added.

[kennykerr]

Oh and the CI build for some reason will only run branches local to this repo.

[dfields-msft]

Does the test infrastructure have any existing support for compile-time negative tests (i.e. code that's expected to not compile)? I can certainly add compile-time and runtime positive tests, as well as a runtime negative test, but I'm not going to bite off setting up test infrastructure for compile-time negative tests if that's not already available...

[kennykerr]

No negative testing unfortunately.

Just need a test that validates it works in a constant expression (e.g. static_assert) and a runtime test that validates it works successfully (e.g. assert) and unsuccessfully (e.g. throw and catch).

[dfields-msft]

@kennykerr I'm not sure how to trigger the "C++ for WinRT Xlang internal build" pipeline run that's required by policy... Is this even possible, since my changes are coming from a different fork? I don't think I have permission to create a branch in the official microsoft fork.

[kennykerr]

I've given you Write access so you should be able to push a branch. Then you can go here and build your branch:

https://dev.azure.com/microsoft/Dart/_build?definitionId=31784

[dfields-msft]

Verified offline that Clang works with these changes too. @kennykerr any additional changes needed, or is this ready to merge?

[dfields-msft]

Thanks for approving the changes, @kennykerr! Looks like I'm not authorized to merge, so you may need to complete this PR yourself...

[kennykerr]

@DefaultRyan or @jlaanstra can you help? I'm on the beach. 😎