Exclude MsHtml APIs

[kennykerr]

These older APIs were only intended for JScript and VBScript clients, but MsHtml is by far the single largest module and as such takes a nice chunk out of the overall package size.

[rylev]

Wow! It would be nice if we clearly documented somewhere which APIs are being excluded since we're now not quite a 1 to 1 mapping to the metadata.

[kennykerr]

Yes, I really need to spend some time and write a more complete FAQ.

[kennykerr]

See #1933

[mwcampbell]

These older APIs were only intended for JScript and VBScript clients

I'm not sure about intention, but the vtable-based interfaces are certainly usable from C++, and presumably would be from Rust as well. I can think of two categories of software that make use of these interfaces: programs that embed the MSHTML engine (usually via the WebBrowser ActiveX control), and assistive technologies (e.g. screen readers) that have specific support for the MSHTML engine (which includes all actively maintained Windows screen readers except Narrator). I wrote one such screen reader (before my time at Microsoft, and it's not so actively maintained now), and if I were to port it to Rust, I would definitely need bindings for the MSHTML API. One may respond that the IE engine is dead anyway, and we may want to just forget about it, but it's still part of Windows, so removing MSHTML seems like going back on the promise of "any Windows API past, present, and future".

Would it be feasible to bring back the MSHTML API in a separate crate? How hard is it to do that for pieces of the Windows SDK, since it all comes from the same metadata and there will likely be cross-crate dependencies?

[kennykerr]

It can be reintroduced in a few different ways if the need arises. The windows-bindgen crate fulfills the promise of "any Windows API past, present, and future", is used to generate the windows crate, and any additional crates for supplemental APIs like this.

[mwcampbell]

OK, if it's feasible to have a separate mshtml crate via windows-bindgen, I will be happy to maintain such a crate if I have the need for it.