signer/core can't compile to wasm due to unix constrains

[goldbock]

System information

go-ethereum tip

Expected behaviour

compile to wasm

Actual behaviour

signer/core package does not compile to wasm

Steps to reproduce the behaviour

import "github.com/ethereum/go-ethereum/signer/core"

Use the signer/core to generate an EIP712Domain signature;

Backtrace

      imports github.com/ethereum/go-ethereum/signer/core
        imports github.com/ethereum/go-ethereum/consensus/clique
        imports github.com/ethereum/go-ethereum/consensus
        imports github.com/ethereum/go-ethereum/core/state
        imports github.com/VictoriaMetrics/fastcache
        imports golang.org/x/sys/unix: build constraints exclude all Go files in /Users/x/go/pkg/mod/golang.org/x/sys@v0.0.0-20210910150752-751e447fb3d0/unix

I've used go-ethereum successfully in wasm environment for a while until I had to use EIP712Domain signature and import types from "signer/core". I've fixed the build tags on fast cache in VictoriaMetrics/fastcache#62 but there seem to be other transitive dependencies such leveldb and edsrzf/mmap-go that require file locking.

I believe the TypedData structs should perhaps be exported in a separate package so that the client can generate EIP712Domain signatures without importing (transitively) leveldb and other packages that require file synchronisation.

A more broad scope would be to make the whole go-ethereum sdk wasm compatible ( #16192 ) but that's a different, bigger issue.

[holiman]

Yes, I guess we can move the TypedData to it's own package. Want to make a PR?
EDIT: I can make the move myself, probably simpler, because we'll probably have a lot of nitpicks about naming and what to put in there etc.

[goldbock]

@holiman I think it would be great if you do it... I will probably mess the package organisation.

As a quick workaround I actually patched (in a brutal/poor way) several packages[0] that throw errors on wasm compilation to make sure that I won't hit unix constraints errors if I ever need to use other go-ethereum packages that have these dependencies.

[0] go-ethereum/accounts/scwallet (disabled support in js)
goleveldb
prometheus-junkyard/tsdb
edsrzf/mmap-go
VictoriaMetrics/fastcache ( easy fix)

[fjl]

Seems to me like package signer/core/apitypes is the ideal location for TypedData. We created this package specifically for types which are used by the RPC API, and it was created because of a similar dependency issue.