Support wasm

[haerdib]

Previous work done: #48

[Niederb]

One issue is that substrate has a dependency on wasmtime. This leads to a compilation error, but it probably does not make sense to compile a webassembly runtime with webassembly to begin with. So we would have to configure our code such that the dependency is not needed.

Compilation error:

...
cargo:warning=src/helpers.c:1:10: fatal error: 'setjmp.h' file not found
...

The dependency is triggered as soon as std is enabled in either sp-core or sp-io. sp-core is used by so many substrate crates that this basically means the dependency is enabled as soon as we enable std on any substrate crate.

Related issue: paritytech/substrate#13087

[haerdib]

Okay. To summarize:

• the api-client is wasm compatible in no-std mode ✔️
• To make std mode wasm compatible we would have to either
  1. get rid of sp-core / sp-io dependencies
  2. only depend on no-std part of spi-io, sp-core (not guaranteed though that it stops here, because the runtime is compiled to wasm in no-std mode)

Correct?

[Niederb]

Yes, pretty much. Basically we would need to make sure that std is not enabled in sp-wasm-interface. See here:
https://github.com/paritytech/substrate/blob/dd45632f298db02f6946c906296bbf86a74f4f46/primitives/wasm-interface/Cargo.toml#L27
I tried by not enabling std in sp-core, but this triggers other issues regarding Serialization/Deserialization and the ones described here paritytech/substrate#13087 (comment)

[Niederb]

Close this for now. See #513 for a follow up issue