[Bug]: [rspack 1.6.1+] RealContentHashPlugin: circular hash dependency

[MatissJanis]

System Info

System:
OS: macOS 26.5.2
CPU: (16) arm64 Apple M4 Max
Memory: 1.65 GB / 64.00 GB
Shell: 5.9 - /bin/zsh
Binaries:
Node: 24.14.1
Yarn: 6.0.0-rc.13
npm: 11.11.0
bun: 1.3.6
Watchman: 2026.05.25.00
Browsers:
Chrome: 150.0.7871.187
Safari: 26.5.2

Details

Rspack panics when multiple async runtime chunks each embed a full chunk-id→[contenthash] map.

Other folks are working around the problem by setting realContentHash: false, but unfortunately that isn't a workable solution for us.

Rspack 1.6.0 works fine, but since 1.6.1 (up to 1.6.8) we run into this panic.

Reproduce link

https://github.com/MatissJanis/rspack-mf-contenthash-repro/tree/master

Reproduce Steps

yarn install
yarn build:mf

[MatissJanis]

To note: I am seeing this same issue in both rspack 1.6.1+ and rspack 2+