First part of glue code for HarfBuzz

[hsivonen]

Towards #2514.

I have reserved the crate name: https://crates.io/crates/icu_harfbuzz

[hsivonen]

Follow-ups: #2840, #2833, #2832, #2838.

[sffc]

I reviewed this with @echeran. Looks quite good; thanks for figuring out how to do these bindings!

[Manishearth]

So at a high level this looks really great!

One thing I'm wondering about is whether this should go into the metacrate. I kind of feel that this isn't an ICU4X component as much as it is an ICU4X integration (or "port"). A lot of the stuff under ffi/ serves this purpose (but in a more general way), I wonder if it's time we had a new "ports" folder for things that use ICU4X to do new exciting things in ways that are themselves crateworthy.

I also don't want a native dependency in our default deptree 😄 We can play around with that, of course.

[sffc]

Agree that it would be nice to avoid native deps in the icu metacrate. I think this should just be a standlone crate.

[hsivonen]

Agree that it would be nice to avoid native deps in the icu metacrate. I think this should just be a standlone crate.

Concretely, how should I place this crate in the repo's directory structure?

[sffc]

Agree that it would be nice to avoid native deps in the icu metacrate. I think this should just be a standlone crate.

Concretely, how should I place this crate in the repo's directory structure?

Discussed in today's call. It should be ffi/harfbuzz eventually, or you can start it as experimental/harfbuzz. It's just that it can be a separate crate icu_harfbuzz without being plugged into the icu metacrate.

[sffc]

@hsivonen What's the status of this PR? Are you waiting on reviewers or is there more you plan to do first?

[sffc]

Discussion: put this in the workspace but not the metacrate.

[hsivonen]

I have both 1) removed icu_harfbuzz from the metacrate and 2) turned off the default features of harfbuzz-sys to build Harfbuzz itself and Freetype.

[hsivonen]

Apparently tests need Harfbuzz itself to be built.