Wasm support

[wehlutyk]

Hi!

There is discussion over at Frommi/miniz_oxide#34 (and previously Frommi/miniz_oxide#26) to support Wasm for miniz_oxide_c_api (on top of miniz_oxide) using the libc-stub hack from alexcrichton/wasm-sodium. From there, it's only a small addition to flate2-rs to make this crate compile to wasm32. Would you take that as PR, or would you rather wait until libc has an implementation for wasm32?

[alexcrichton]

Sounds like a great idea to me!

I think we should enable the rust-backend feature by default on wasm to make sure flate2 builds by default on wasm as well!

[wehlutyk]

Great!

Ah yes, the rust_backend thing would be nice. I currently have to surface that feature through client crates of flate2-rs such as lopdf.

Will be back once the miniz_oxide change is made.

Edit: realising that's already possible in my fork, I didn't know it was possible!

[wehlutyk]

Correction: I can't find a way to set a default feature for a given target. Are you referring to rust-lang/cargo#1197?

[alexcrichton]

Nah we'd just hardcode this in the code, an unconditional target-specific dependency would be added for wasm and then on wasm the code would unconditionally (regardless of features) use miniz_oxide

[alexcrichton]

This should be implemented now!