wasm-pack build fails for WebRTC + gossipsub in libp2p v0.56.0 due to ahash → getrandom v0.3.4

[fgtest1]

Summary

When building a WASM P2P node with gossipsub and webrtc-websys in libp2p v0.56.0, the build fails due to an unresolved getrandom backend requirement, even though all correct features are enabled.

This blocks browser-to-browser gossipsub in WASM until either:

• The ahash dependency is fully removed from gossipsub, or
• Proper WebRTC transport APIs are exposed in SwarmBuilder.

Steps to Reproduce

1. Create a minimal WASM crate with:

   [dependencies.libp2p]
   version = "0.56.0"
   default-features = false
   features = [
     "webrtc-websys",
     "noise",
     "wasm-bindgen",
     "gossipsub"
   ]
   
   

2. Implement a basic NetworkBehaviour with gossipsub::Behaviour
3. Try to build with:wasm-pack build --target web
   4.Expected Behavior
   Compiles successfully (as implied by docs and examples)
   WebRTC transport works via .with_webrtc() or equivalent

Actual Behavior
Error 1: Missing .with_webrtc() method
error[E0599]: no method named with_webrtc found for struct SwarmBuilder<...>

Error 2: getrandom v0.3.4 fails in WASM

This happens because:

libp2p-gossipsub v0.49.2 → hashlink → hashbrown → ahash → getrandom v0.3.4
ahash does not enable the wasm_js feature on its getrandom dependency
Even if I add getrandom = { version = "0.3.4", features = ["wasm_js"] },
Cargo doesn’t propagate the feature to transitive deps

Workarounds Tried
✅ Removing gossipsub → compiles (but loses pubsub)
✅ Using websocket-websys instead → works, but requires relay
❌ Adding "serde" or "other" features → doesn’t fix missing .with_webrtc()
❌ Patching getrandom → fails due to ahash hard dependency

Environment
libp2p version: 0.56.0
Rust version: rustc 1.83.0 (or latest stable)
Target: wasm32-unknown-unknown
OS: Windows 11 (but reproducible on Linux/macOS)

Additional Context
PR #5098 replaced ahash with fxhash, which should fix the getrandom issue
However, v0.56.0 still uses ahash, and there’s no published version with the fix
Also, the WebRTC transport API (SwarmBuilder::with_webrtc()) appears to be missing or unstable

Request
Release v0.57.0 with the ahash → fxhash migration (from #5098)
Document the correct way to use WebRTC in WASM — current examples reference .with_webrtc(), but it doesn’t exist in v0.56.0
Clarify whether gossipsub is truly WASM-compatible today

Thank you for your work on libp2p

[lat-murmeldjur]

for me this solved it:

RUSTFLAGS='--cfg getrandom_backend="wasm_js"' wasm-pack build --target web --out-dir static

in cargo.toml:

getrandom = { version = "0.3.3", features = ["wasm_js"] }