fflonk -> w3f-pcs rename breaking polkadot-omni-node installation and polkadot-sdk cargo update

[Yung-Beef]

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Description of bug

This fflonk W3F package was renamed to w3f-pcs yesterday

From this page I am trying cargo install --git https://github.com/paritytech/polkadot-sdk --tag polkadot-stable2412 --force polkadot-omni-node and getting:

error: failed to compile `polkadot-omni-node v0.1.0 (https://github.com/paritytech/polkadot-sdk?tag=polkadot-stable2412#967989c5)`, intermediate artifacts can be found at `/tmp/cargo-installM8reWS`.
To reuse those artifacts with a future compilation, set the environment variable `CARGO_TARGET_DIR` to that path.

Caused by:
  no matching package named `fflonk` found
  location searched: Git repository https://github.com/w3f/fflonk
  required by package `ring v0.1.0 (https://github.com/w3f/ring-proof?rev=665f5f5#665f5f51)`
      ... which satisfies git dependency `ring` of package `bandersnatch_vrfs v0.0.4 (https://github.com/w3f/ring-vrf?rev=0fef826#0fef8266)`
      ... which satisfies git dependency `bandersnatch_vrfs` of package `sp-core v28.0.0 (/home/tgang/.cargo/git/checkouts/polkadot-sdk-cff69157b985ed76/967989c/substrate/primitives/core)`
      ... which satisfies path dependency `sp-core` of package `polkadot-omni-node-lib v0.1.0 (/home/tgang/.cargo/git/checkouts/polkadot-sdk-cff69157b985ed76/967989c/cumulus/polkadot-omni-node/lib)`
      ... which satisfies path dependency `polkadot-omni-node-lib` of package `polkadot-omni-node v0.1.0 (/home/tgang/.cargo/git/checkouts/polkadot-sdk-cff69157b985ed76/967989c/cumulus/polkadot-omni-node)`

I see fflonk is still in the root Cargo.lock a few times so something needs to be updated.

Steps to reproduce

No response

[drskalman]

Sorry for the inconveniences 😔🙏 This was long time due. We had to have published the crate to crates.io long time ago w3f/ring-proof#38. It should be more stable now with versioning and crates.io so we don't break everything when we make progress on ring proof side.

The repo's name was no longer representative of what it is doing as it is not only fflonk but is a collection of polynomial commitments. So we should all move on to depend on https://crates.io/crates/w3f-pcs/ now. Thanks a lot.

[cmichi]

@Yung-Beef We also ran into the issue. We hotfixed it like this in our workspace Cargo.toml:

# hotfix for https://github.com/paritytech/polkadot-sdk/issues/7653
[patch.'https://github.com/w3f/fflonk']
fflonk = { git = "https://www.github.com/w3f/fflonk", rev = "be95d4c971b1d15b5badfc06ff13f5c07987d484" }

[drskalman]

@davxy maybe you could fix this quickily?

[davxy]

It seems the quick'n dirty solution here would be to adopt the same approach as in paritytech/verifiable#8. Specifically, we can point to bandersnatch_vrfs to lock in a fixed revision of ring_proof, which in turn relies on a fixed revision of fflonk. I’ll aim to prepare the patch tomorrow. After that, I’ll focus on replacing bandersnatch_vrfs with ark-ec-vrfs to implement a more robust and permanent fix.