feat!: merge barretenberg_static_lib and barretenberg_wasm

[TomAFrench]

This PR starts the work of merging this workspace into a single crate. To simplify things, I've restricted the public interface of the crate to just be the Plonk struct (as this is necessary for nargo) to avoid any differences in the interface between targets. We should decide what else we want to expose before merging this.

The interfaces of most methods are identical between native and wasm backends. In these cases I've copied across the implementation from barretenberg_wasm and placed it in inside the function body from barretenberg_static_lib, these are then switched between with feature flags.

In a couple of cases the struct interfaces are different (Barretenberg/StandardComposer/Pippenger) so I've had to swap them out entirely based on the feature flags.

[phated]

Do these need to specify dep:?

[TomAFrench]

Do these need to specify dep:?

I initially had dep: on here but that means we run into this error:

error: Package `acvm-backend-barretenberg v0.1.0 (/home/tom/Programming/aztec_backend/acvm_backend_barretenberg)` does not have feature `wasmer`.
It has an optional dependency with that name, but that dependency uses the "dep:" syntax in the features table, so it does not have an implicit feature with that name.

So it seems like having a dep: flag conflicts with switching on feature flags on that dependency. (adding dep: to the other wasmer flags also results in an error.)

https://doc.rust-lang.org/cargo/reference/features.html#optional-dependencies

[TomAFrench]

Tomorrow I'll probably break out the different flavours of src/lib.rs into separate files for native/wasm backends. It's pretty messy with the chonky if-else.

[TomAFrench]

We're currently only testing the native backend due to us merging these two crates. I'd like to pass in the different feature flags so we can build/test the flake with both backends as otherwise we'll not be testing the wasm backend.

[kevaundray]

Left some general comments; was reading to understand more about this issue: noir-lang/acvm#211

[phated]

Some things I noticed when I pulled this down locally.

[TomAFrench]

Ah, this still needs the multiple outputs (native vs wasm) added to the flake as well.

[phated]

I noticed a few more things. I wonder if we can drop the cfg-if block for all the setup but I won't block on it.

[TomAFrench]

I wonder if we can drop the cfg-if block for all the setup but I won't block on it.

I don't see a good way to do this. Rust doesn't seem to like putting a scope around the two branches (similarly to how we do in pow2ceil) so we'd have to add the cfg to each and every element inside which would be uglier.

[phated]

I don't see a good way to do this. Rust doesn't seem to like putting a scope around the two branches (similarly to how we do in pow2ceil) so we'd have to add the cfg to each and every element inside which would be uglier.

I'm wondering if it would be better/worse to use your cfg on a mod like you did for crs.rs?

[TomAFrench]

You asked me to revert that change though 🫠 Ah gotcha, we can do it in a single file.

Yeah, I'm happy with that as it encapsulates more of the wasm internals.

[phated]

This is awesome! Let's get it merged so we can keep iterating on this crate 🎉