Set windows-implement min rust-version

[wravery]

Both the #[implement] macro and the implement feature in windows require newly stabilized features in rustc 1.61 (which just hit stable 🎉). We can specify it on the macro crate so anyone who wants to use the macro knows they need to update their toolchain and gets a clear error message if they don't.

I don't think you can specify a conditional rust-version which depends on the feature, but if there's a way to do that it would make sense to add it to the windows crate as well.

[kennykerr]

As part of #1771 I planned to remove the nightly restriction for testing. It is not sufficient to set the rust-version (although definitely a good move) as we also need to ensure that the yml scripts actually test that version. It's probably simplest to set the min version for the windows crate as a whole and test that via the yml scripts. The yml scripts are currently only testing 1.59 and nightly. The yml scripts are generated here:

https://github.com/microsoft/windows-rs/blob/master/crates/tools/yml/src/main.rs

[wravery]

As part of #1771 I planned to remove the nightly restriction for testing. It is not sufficient to set the rust-version (although definitely a good move) as we also need to ensure that the yml scripts actually test that version. It's probably simplest to set the min version for the windows crate as a whole and test that via the yml scripts. The yml scripts are currently only testing 1.59 and nightly. The yml scripts are generated here:

https://github.com/microsoft/windows-rs/blob/master/crates/tools/yml/src/main.rs

OK, do you mean that you would like me to add rust-version to windows and update the yml script (presumably to update stable and nightly, and drop/replace 1.59 with stable) in the same PR? Or is that more of a forward-looking suggestion for another PR?

[kennykerr]

Updating the yml generation is a much bigger job - happy for you to do it if you're in a hurry - but equally happy for you to wait until I've wrapped that up in a few days. I'm just not comfortable updating the rust-version without testing. I hope to get that done next week.

[wravery]

Updating the yml generation is a much bigger job - happy for you to do it if you're in a hurry - but equally happy for you to wait until I've wrapped that up in a few days. I'm just not comfortable updating the rust-version without testing. I hope to get that done next week.

OK, what about updating just windows-implement in this PR first, then? It looks like it passed all the CI checks, but I guess that means they aren't testing the macro crate (or only testing it on nightly)?

[kennykerr]

Yep, it's only testing with nightly. I think the change is harmless now that 1.61 is stable, so I'll take it but yeah there's more work to be done.

[wravery]

I think this may have already made the conditional MSRV work. When you add the implement feature to windows, it adds windows-implement as a dependency, right? When it tries to build windows-implement, it should already error out for its greater MSRV on earlier toolchains. 😄

[kennykerr]

Yep... 😄 Although testing that would mean having to have different runs for the different min versions.