Oz proxy backwards compatible

[bunsenstraat]

• allows deploying and upgrading on v4 and v5 of the erc1967 proxy
• add tests for both versions plus tests for the debugger

how to test:

• add a token, v5 will require version > 8.20:
• v5 can be added using remix templates
• v4 example:

      // SPDX-License-Identifier: MIT
      pragma solidity ^0.8.4;
      
      import "@openzeppelin/contracts-upgradeable@4.8.3/token/ERC721/ERC721Upgradeable.sol";
      import "@openzeppelin/contracts-upgradeable@4.8.3/access/OwnableUpgradeable.sol";
      import "@openzeppelin/contracts-upgradeable@4.8.3/proxy/utils/Initializable.sol";
      import "@openzeppelin/contracts-upgradeable@4.8.3/proxy/utils/UUPSUpgradeable.sol";
      
      contract MyToken is Initializable, ERC721Upgradeable, OwnableUpgradeable, UUPSUpgradeable {
          /// @custom:oz-upgrades-unsafe-allow constructor
          constructor() {
              _disableInitializers();
          }
      
          function initialize() initializer public {
              __ERC721_init("MyToken", "MTK");
              __Ownable_init();
              __UUPSUpgradeable_init();
          }
      
          function _authorizeUpgrade(address newImplementation)
              internal
              onlyOwner
              override
          {}
      }

• deploy this with proxy, for v5 add an address at parameter
• upgrade this contract with:

      import "./myTokenV1.sol";

      contract MyTokenV2 is MyToken {
        function version () public view returns (string memory) {
            return "MyTokenV2!";
        }
    }

• run a call ie 'version' on the second deployed proxy
• it should return MyTokenV2!
• run the debugger on this call

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[yann300]

this part didn't change too right? except of the new logs in the terminal.

[bunsenstraat]

no it's wrapped in a callback from the tx that gets the version of the erc

[bunsenstraat]

so it makes two calls depending on the version