How to change deployed bytecode of a given contract

Example foundry project demonstrating how to change the bytecode of a deployed contract. This example is heavily inspired by this excellent talk.

How Does it work ?

Summary

The "trick" to change bytecode of a deployed contract consists of combining a selfdestruct call on the original implementation and then redeploying different bytecode to the same address using CREATE2.

Required contracts

1. Contract whose constructor returns bytecode loaded from another contract, instead of its own compiled source code. Choice.sol
2. Contract that can control the bytecode to be deployed in storage and creates an instance of above mentioned contract with CREATE2
3. Implementations that contain a selfdestruct call. (ContractV1,ContractV2)

Transactions to execute

1. Deploy Overwrite.sol contract. (DeployDependencies.sol)
2. Call Overwrite contract and set the code to be deployed to the first version.(SetCode.sol)
3. Call Overwrite contract and deploy contract with given salt value. (CreateInstance.sol)
4. Call selfdestruct method on the deployed instance (DestroyInstance.sol)
5. Repeat step 2 with the new bytecode
6. Repeat step 3 using the same salt value

Getting started

Install Foundry

The best source of documentation is the foundry-book which contains chapters on all elements of the framework.

1. Install foundryup tool by running curl -L https://foundry.paradigm.xyz | bash
2. Install / Update foundry with foundryup

Install dependencies

forge install

Run tests

forge test