Yield Delegation / Rebasing Token Rewrite

contracts/contracts/echidna/EchidnaHelper.sol

@@ -131,42 +131,6 @@ contract EchidnaHelper is EchidnaSetup {
         ousd.approve(spender, amount);
     }
 
-    /**
-     * @notice Increase the allowance of an account to spend OUSD
-     * @param ownerAcc Account that owns the OUSD
-     * @param spenderAcc Account that is approved to spend the OUSD
-     * @param amount Amount to increase the allowance by
-     */
-    function increaseAllowance(
-        uint8 ownerAcc,
-        uint8 spenderAcc,
-        uint256 amount
-    ) public {
-        address owner = getAccount(ownerAcc);
-        address spender = getAccount(spenderAcc);
-        hevm.prank(owner);
-        // slither-disable-next-line unused-return
-        ousd.increaseAllowance(spender, amount);
-    }
-
-    /**
-     * @notice Decrease the allowance of an account to spend OUSD
-     * @param ownerAcc Account that owns the OUSD
-     * @param spenderAcc Account that is approved to spend the OUSD
-     * @param amount Amount to decrease the allowance by
-     */
-    function decreaseAllowance(
-        uint8 ownerAcc,
-        uint8 spenderAcc,
-        uint256 amount
-    ) public {
-        address owner = getAccount(ownerAcc);
-        address spender = getAccount(spenderAcc);
-        hevm.prank(owner);
-        // slither-disable-next-line unused-return
-        ousd.decreaseAllowance(spender, amount);
-    }
-
     /**
      * @notice Get the sum of all OUSD balances
      * @return total Total balance

contracts/contracts/echidna/EchidnaSetup.sol

@@ -19,7 +19,7 @@ contract EchidnaSetup is EchidnaConfig {
      * @notice Deploy the OUSD contract and set up initial state
      */
     constructor() {
-        ousd.initialize("Origin Dollar", "OUSD", ADDRESS_VAULT, 1e18);
+        ousd.initialize(ADDRESS_VAULT, 1e18);
 
         // Deploy dummny contracts as users
         Dummy outsider = new Dummy();

contracts/contracts/echidna/EchidnaTestApproval.sol

@@ -94,46 +94,4 @@ contract EchidnaTestApproval is EchidnaTestMintBurn {
 
         assert(allowanceAfter2 == amount / 2);
     }
-
-    /**
-     * @notice Increasing the allowance should raise it by the amount provided
-     * @param ownerAcc The account that is approving
-     * @param spenderAcc The account that is being approved
-     * @param amount The amount to approve
-     */
-    function testIncreaseAllowance(
-        uint8 ownerAcc,
-        uint8 spenderAcc,
-        uint256 amount
-    ) public {
-        address owner = getAccount(ownerAcc);
-        address spender = getAccount(spenderAcc);
-
-        uint256 allowanceBefore = ousd.allowance(owner, spender);
-        increaseAllowance(ownerAcc, spenderAcc, amount);
-        uint256 allowanceAfter = ousd.allowance(owner, spender);
-
-        assert(allowanceAfter == allowanceBefore + amount);
-    }
-
-    /**
-     * @notice Decreasing the allowance should lower it by the amount provided
-     * @param ownerAcc The account that is approving
-     * @param spenderAcc The account that is being approved
-     * @param amount The amount to approve
-     */
-    function testDecreaseAllowance(
-        uint8 ownerAcc,
-        uint8 spenderAcc,
-        uint256 amount
-    ) public {
-        address owner = getAccount(ownerAcc);
-        address spender = getAccount(spenderAcc);
-
-        uint256 allowanceBefore = ousd.allowance(owner, spender);
-        decreaseAllowance(ownerAcc, spenderAcc, amount);
-        uint256 allowanceAfter = ousd.allowance(owner, spender);
-
-        assert(allowanceAfter == allowanceBefore - amount);
-    }
 }

contracts/contracts/echidna/OUSDEchidna.sol

@@ -10,6 +10,7 @@ contract OUSDEchidna is OUSD {
         public
         returns (bool)
     {
-        return _isNonRebasingAccount(_account);
+        _autoMigrate(_account);
+        return alternativeCreditsPerToken[_account] > 0;
     }
 }

contracts/contracts/flipper/Flipper.sol

@@ -19,7 +19,7 @@ contract Flipper is Governable {
 
     // Settable coin addresses allow easy testing and use of mock currencies.
     IERC20 immutable dai;
-    OUSD immutable ousd;
+    address immutable ousd;
     IERC20 immutable usdc;
     Tether immutable usdt;
 
@@ -37,7 +37,7 @@ contract Flipper is Governable {
         require(address(_usdc) != address(0));
         require(address(_usdt) != address(0));
         dai = IERC20(_dai);
-        ousd = OUSD(_ousd);
+        ousd = _ousd;
         usdc = IERC20(_usdc);
         usdt = Tether(_usdt);
     }
@@ -54,7 +54,10 @@ contract Flipper is Governable {
             dai.transferFrom(msg.sender, address(this), amount),
             "DAI transfer failed"
         );
-        require(ousd.transfer(msg.sender, amount), "OUSD transfer failed");
+        require(
+            IERC20(ousd).transfer(msg.sender, amount),
+            "OUSD transfer failed"
+        );
     }
 
     /// @notice Sell OUSD for Dai
@@ -63,7 +66,7 @@ contract Flipper is Governable {
         require(amount <= MAXIMUM_PER_TRADE, "Amount too large");
         require(dai.transfer(msg.sender, amount), "DAI transfer failed");
         require(
-            ousd.transferFrom(msg.sender, address(this), amount),
+            IERC20(ousd).transferFrom(msg.sender, address(this), amount),
             "OUSD transfer failed"
         );
     }
@@ -77,7 +80,10 @@ contract Flipper is Governable {
             usdc.transferFrom(msg.sender, address(this), amount / 1e12),
             "USDC transfer failed"
         );
-        require(ousd.transfer(msg.sender, amount), "OUSD transfer failed");
+        require(
+            IERC20(ousd).transfer(msg.sender, amount),
+            "OUSD transfer failed"
+        );
     }
 
     /// @notice Sell OUSD for USDC
@@ -89,7 +95,7 @@ contract Flipper is Governable {
             "USDC transfer failed"
         );
         require(
-            ousd.transferFrom(msg.sender, address(this), amount),
+            IERC20(ousd).transferFrom(msg.sender, address(this), amount),
             "OUSD transfer failed"
         );
     }
@@ -102,7 +108,10 @@ contract Flipper is Governable {
         // USDT does not return a boolean and reverts,
         // so no need for a require.
         usdt.transferFrom(msg.sender, address(this), amount / 1e12);
-        require(ousd.transfer(msg.sender, amount), "OUSD transfer failed");
+        require(
+            IERC20(ousd).transfer(msg.sender, amount),
+            "OUSD transfer failed"
+        );
     }
 
     /// @notice Sell OUSD for USDT
@@ -113,7 +122,7 @@ contract Flipper is Governable {
         // so no need for a require.
         usdt.transfer(msg.sender, amount / 1e12);
         require(
-            ousd.transferFrom(msg.sender, address(this), amount),
+            IERC20(ousd).transferFrom(msg.sender, address(this), amount),
             "OUSD transfer failed"
         );
     }
@@ -125,7 +134,7 @@ contract Flipper is Governable {
     /// @dev Opting into yield reduces the gas cost per transfer by about 4K, since
     /// ousd needs to do less accounting and one less storage write.
     function rebaseOptIn() external onlyGovernor nonReentrant {
-        ousd.rebaseOptIn();
+        OUSD(ousd).rebaseOptIn();
     }
 
     /// @notice Owner function to withdraw a specific amount of a token
@@ -142,7 +151,10 @@ contract Flipper is Governable {
     /// again by transferring assets to the contract.
     function withdrawAll() external onlyGovernor nonReentrant {
         IERC20(dai).safeTransfer(_governor(), dai.balanceOf(address(this)));
-        IERC20(ousd).safeTransfer(_governor(), ousd.balanceOf(address(this)));
+        IERC20(ousd).safeTransfer(
+            _governor(),
+            IERC20(ousd).balanceOf(address(this))
+        );
         IERC20(address(usdt)).safeTransfer(
             _governor(),
             usdt.balanceOf(address(this))

contracts/contracts/mocks/MockNonRebasing.sol

@@ -34,8 +34,8 @@ contract MockNonRebasing {
         oUSD.transferFrom(_from, _to, _value);
     }
 
-    function increaseAllowance(address _spender, uint256 _addedValue) public {
-        oUSD.increaseAllowance(_spender, _addedValue);
+    function approve(address _spender, uint256 _addedValue) public {
+        oUSD.approve(_spender, _addedValue);
     }
 
     function mintOusd(

contracts/contracts/mocks/TestUpgradedOUSD.sol

@@ -0,0 +1,25 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.0;
+
+import "../token/OUSD.sol";
+
+// used to alter internal state of OUSD contract
+contract TestUpgradedOUSD is OUSD {
+    constructor() OUSD() {}
+
+    function overwriteCreditBalances(address _account, uint256 _creditBalance)
+        public
+    {
+        creditBalances[_account] = _creditBalance;
+    }
+
+    function overwriteAlternativeCPT(address _account, uint256 _acpt) public {
+        alternativeCreditsPerToken[_account] = _acpt;
+    }
+
+    function overwriteRebaseState(address _account, RebaseOptions _rebaseOption)
+        public
+    {
+        rebaseState[_account] = _rebaseOption;
+    }
+}

contracts/contracts/token/OETH.sol

@@ -8,5 +8,15 @@ import { OUSD } from "./OUSD.sol";
  * @author Origin Protocol Inc
  */
 contract OETH is OUSD {
+    function symbol() external pure override returns (string memory) {
+        return "OETH";
+    }
 
+    function name() external pure override returns (string memory) {
+        return "Origin Ether";
+    }
+
+    function decimals() external pure override returns (uint8) {
+        return 18;
+    }
 }

contracts/contracts/token/OETHBase.sol

@@ -2,20 +2,21 @@
 pragma solidity ^0.8.0;
 
 import { OUSD } from "./OUSD.sol";
-import { InitializableERC20Detailed } from "../utils/InitializableERC20Detailed.sol";
 
 /**
  * @title OETH Token Contract
  * @author Origin Protocol Inc
  */
 contract OETHBase is OUSD {
-    /**
-     * @dev OETHb is already intialized on Base. So `initialize`
-     *      cannot be used again. And the `name` and `symbol`
-     *      methods aren't `virtual`. That's the reason this
-     *      function exists.
-     */
-    function initialize2() external onlyGovernor {
-        InitializableERC20Detailed._initialize("Super OETH", "superOETHb", 18);
+    function symbol() external pure override returns (string memory) {
+        return "superOETHb";
+    }
+
+    function name() external pure override returns (string memory) {
+        return "Super OETH";
+    }
+
+    function decimals() external pure override returns (uint8) {
+        return 18;
     }
 }