Cancun Network Upgrade Meta Thread

Cancun Network Upgrade Meta Thread (Jan '23 update)

On ACDE#153, we agreed to try out Network Upgrade Meta Threads for Cancun.

Instead of creating a new thread, we can repurpose this one given there were already some comments here. We can use this to discuss things like:

  • What should be the main priority/priorities for the upgrade;
  • When, roughly, should we aim for the upgrade to happen, and the tradeoffs of including a marginal feature vs. delaying;
  • How to split multi-upgrade features across >1 upgrade, and the implications of including a subset of those features in a specific upgrade

I’ll keep a list of notable proposals/suggestions updated here to make it easy to scan.

Note: EIP champions who’d like to propose their EIP for Cancun should add the cancun-candidate tag to a post about the EIP on this forum.

Dec 2022 Shanghai/Cancun Proposals:

Original Post (Dec '22)

Click to expand

Similarly to what we did for Shanghai, I propose using this thread to discuss how we should go about choosing EIPs for the post-Shanghai EL upgrade, Cancun.

At the very least, EIPs which wish to be considered for the upgrade should add the cancun-candidate to either their existing EthMagicians topics, or create a new one focused on Cancun consideration.

For context, please refer to AllCoreDevs 151. Here is a summary posted to the R&D discord:

and a relevant Cancun comment by @protolambda:


I’d like to raise that perhaps the discussions around SELFDESTRUCT may benefit from a revival. There are two bigger proposals on the topic: EIP-4758 and EIP-6046.

A new analysis was shared lately by @jwasinger.


Solidity would like to propose EIP-663 for Cancun. It has been EFI before in 2019-2020, dependent on immediate arguments. EOF provides that trivially, so it’s fair to say that with EOF 663’s issues become resolved. It’s supported by Solidity, Vyper and Huff, the main direct users of 663. I need to check with Fe as well, but I don’t think they’d be against because they currently compile to Yul which would benefit from this. With 663:

  • All languages can save gas by not moving local variables to memory when they don’t fit on the reachable part of the stack anymore.
  • Solidity specifically can cut a big chunk of its roadmap short. The item of “solving stack-too-deep errors”, which include complex optimizers and transformations would simply be done. This also benefits any other language that wishes to optimize local variables by always keeping them on the stack. This consequently brings security advantages by avoiding complex compiler behavior.

If EOF goes in Shanghai, I don’t think it would be possible to add 663 as well.
If EOF goes in Cancun, I think there would be time to add 663 as well given the time until then and how simple it is.


I would like to propose EIP-5920: PAY opcode. I won’t provide a motivation here, since you can just read the motivation section of the EIP itself.

1 Like

In relation to the selfdestruct stuff, I would like to propose EIP-6190 as a non-breaking selfdestruct solution.


Thanks for creating this Tim. Some opinions my own and some the Besu team’s:

  • Priorities should be EOF and 4844, (and whatever consensus we reach on SELFDESTRUCT). The EIP grab-bag approach from Shanghai, while useful, should be limited if we can. There are often many details that come up during the implementation phase and I think it would be best to avoid creep on this already large fork.
  • I think the progress on 4844 in the workshop should drive a timeline. We initially dubbed this a fast-follow fork, which sounds like early 2H. With Shanghai, timelines are dictated by our need to ship withdrawals. While we can accumulate some tech-debt in Shanghai for withdrawals as we have a chance to correct it in Cancun, more pervasive protocol changes in 4844 and EOF will be quickly enshrined tools, langs, and live contracts. To this end, delays are more prudent than shipping “something,” especially with EOF and EVM version requiring support in clients and languages.
  • I have no preference on this - protocol schedules are flexible. We can ship code that lives dormant for a while on Mainnet while we iron it out elsewhere. Weakly in favor of ship often, test often approach.



I’d like to propose EIP-1153 for inclusion in Cancun. I’ve updated the candidate thread with the latest status. Further progress on EIP-1153 is blocked by marking it for inclusion, allowing it to be part of devnets and giving client developers a reason to finish code reviews and merge the outstanding PRs.

And some meta commentary: the main reason EIP-1153 is not in Shanghai is that EOF was added in December and removed a month later. I think this is a failure of prioritization that deserves more discussion. I’d suggest this time around not committing to anything else (other than EIP-4844) for which the spec is not finalized, and EOF is still figuring out parts of the spec (e.g. just a week ago DELEGATECALL into legacy code was brought up).

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To increase Layer 2 adoption we need lower cost transactions, hence the need for EIP4844.

Shapella was focused on withdraOWLs :owl:.
Dencun (Cancun + Deneb) should focus on blobspace :blowfish:.
The timeline for Cancun should be based on EIP4844 readiness. e.g. May/June.

Any additional EIPs should have finalized specs and not add significant delay (e.g. more that 1-2 months) to the delivery of Cancun, otherwise they should be candidates for inclusion in the Prague upgrade later in 2023 or early 2024.

EIPs to add to Cancun in addition to EIP4844

Assume finalized EIP spec and EIPs don’t add significant delay to delivery of Cancun.

  • EIP1153: Transient storage opcodes
  • EIP2537: Precompile for BLS12-381 curve operations
  • EOF
  • Other (reply with details)

0 voters

It’s simple and the spec is basically finalized. There’s a PR to add it to nethermind: Add EIP-5920 by Pandapip1 · Pull Request #5166 · NethermindEth/nethermind · GitHub

EIP2537 or a new implementation for a BLS precompile would be great in order to make it easier for decentralized off-chain networks Lido or Gelato to utilize BLS for threshold signatures.