overview of interop ERC20 support

[jakim929]

Context

#82
Goal: provide context / coalesce interop ERC20 efforts so we can decide what features to build into supersim

Different types of tokens

source https://www.notion.so/defi-wonderland/Extending-SuperchainERC20-to-L2-native-tokens-and-custom-e91ca08dd3eb4434834bf74f56237abf

1. standard L1 bridged: this is the primary focus right now, and has been specced out mostly
2. standard L2 native
3. custom L1 bridged: ie. uses a special bridge / escrow
4. custom L2 native

Overview of specs / implementations so far

SuperchainERC20

• specs: https://specs.optimism.io/interop/token-bridging.html#interface
• High level interface for all interoperable ERC20
• Specified that it should be built on top of the L2ToL2CrossDomainMessenger for messaging capabilities
• functions
  • sendERC20(address _to, uint256 _amount, uint256 _chainId)
  • relayERC20(address _from, address _to, uint256 _amount)
• events
  • event SendERC20(address indexed from, address indexed to, uint256 amount, uint256 destination)
  • event RelayERC20(address indexed from, address indexed to, uint256 amount, uint256 source)

OptimismSuperchainERC20

• impl: OptimismSuperchainERC20
• implements the SuperchainERC20 interface
• bridged version of an L1 native token
• allows the L2StandardBridge to burn / mint tokens on interop
• also allows burning / minting when sendERC20 / relayERC20 is called
• post interop, ALL L1 native tokens will have two representations on the L2: OptimismMintableERC20 and OptimismSuperchainERC20

SuperchainERC20 factory

• design docs: design-doc: SuperchainERC20 Factory for L1 native tokens design-docs#50
• deploys the OptimismSuperchainERC20 contract specified above using Create3, and stores the deployment details in storage

L2StandardBridge upgrade: Liquidity migration

• specs: interop: liquidity migration specs specs#294
• Upgrades the L2StandardBridge to support the following function convert(address _from, address _to, uint256 _amount)
  • allows between existing OptimismMintableERC20 <> OptimismSuperchainERC20 using the L2StandardBridge
• This is how an existing L2 ERC20 based on a L1 native ERC20 will be upgraded to be interoperable

SuperchainWETH

• specs: https://specs.optimism.io/interop/superchain-weth.html
• impl: feat: introduce SuperchainWETH and ETHLiquidity optimism#11042
• WETH implementation that conforms to SuperchainERC20

Notes

• The primary focus currently is support for L1 native, deposited ERC20s
  • design-doc: SuperchainERC20 Factory for L1 native tokens design-docs#50 (comment)
• We'll need better tooling (CLI?) for handling multi-chain deployments (for ERC20 contracts)
  • the factories will use CREATE3 to create deterministic addresses across chains
  • ideally something like supersim deploy --all MyContract.sol
• The contracts (OptimismSuperchainERC20, OptimismSuperchainERC20Factory, new L2StandardBridge) are still in development, we should wait until they are finalized before using it
• We're still unable to import the monorepo contracts and build it inside supersim foundry environment. This will hinder our ability to tweak / build on top of the existing contracts