remove idle supply

.github/workflows/foundry.yml

@@ -80,12 +80,12 @@ jobs:
         include:
           - type: "slow"
             fuzz-runs: 32768
-            max-test-rejects: 1048576
+            max-test-rejects: 16777216
             invariant-runs: 64
             invariant-depth: 1024
           - type: "fast"
             fuzz-runs: 256
-            max-test-rejects: 65536
+            max-test-rejects: 262144
             invariant-runs: 16
             invariant-depth: 256
 

foundry.toml

@@ -14,6 +14,8 @@ tenderly = "https://rpc.tenderly.co/fork/${TENDERLY_FORK_ID}"
 [profile.default.fmt]
 wrap_comments = true
 
+[profile.default.fuzz]
+max_test_rejects = 16777216
 
 [profile.build]
 via-ir = true

src/MetaMorpho.sol

@@ -65,8 +65,8 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
     /// @notice The fee recipient.
     address public feeRecipient;
 
-    /// @notice The rewards recipient.
-    address public rewardsRecipient;
+    /// @notice The skim recipient.
+    address public skimRecipient;
 
     /// @notice The pending guardian.
     PendingAddress public pendingGuardian;
@@ -89,10 +89,6 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
     /// without duplicate.
     Id[] public withdrawQueue;
 
-    /// @notice Stores the idle liquidity.
-    /// @dev The idle liquidity does not generate any interest.
-    uint256 public idle;
-
     /// @notice Stores the total assets managed by this vault when the fee was last accrued.
     uint256 public lastTotalAssets;
 
@@ -183,13 +179,13 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
         emit EventsLib.SetIsAllocator(newAllocator, newIsAllocator);
     }
 
-    /// @notice Sets `rewardsRecipient` to `newRewardsRecipient`.
-    function setRewardsRecipient(address newRewardsRecipient) external onlyOwner {
-        if (newRewardsRecipient == rewardsRecipient) revert ErrorsLib.AlreadySet();
+    /// @notice Sets `skimRecipient` to `newSkimRecipient`.
+    function setSkimRecipient(address newSkimRecipient) external onlyOwner {
+        if (newSkimRecipient == skimRecipient) revert ErrorsLib.AlreadySet();
 
-        rewardsRecipient = newRewardsRecipient;
+        skimRecipient = newSkimRecipient;
 
-        emit EventsLib.SetRewardsRecipient(newRewardsRecipient);
+        emit EventsLib.SetSkimRecipient(newSkimRecipient);
     }
 
     /// @notice Submits a `newTimelock`.
@@ -376,6 +372,8 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
 
             if (supplyCap == 0) revert ErrorsLib.UnauthorizedMarket(id);
 
+            if (allocation.assets == type(uint256).max) allocation.assets = totalWithdrawn.zeroFloorSub(totalSupplied);
+
             (uint256 suppliedAssets,) =
                 MORPHO.supply(allocation.marketParams, allocation.assets, allocation.shares, address(this), hex"");
 
@@ -386,14 +384,7 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
             totalSupplied += suppliedAssets;
         }
 
-        if (totalWithdrawn > totalSupplied) {
-            idle += totalWithdrawn - totalSupplied;
-        } else {
-            uint256 idleSupplied = totalSupplied - totalWithdrawn;
-            if (idle < idleSupplied) revert ErrorsLib.InsufficientIdle();
-
-            idle -= idleSupplied;
-        }
+        if (totalWithdrawn != totalSupplied) revert ErrorsLib.InconsistentReallocation();
     }
 
     /* ONLY GUARDIAN FUNCTIONS */
@@ -451,17 +442,15 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
         _setCap(id, pendingCap[id].value);
     }
 
-    /// @notice Transfers `token` rewards collected by the vault to the `rewardsRecipient`.
-    /// @dev Can be used to extract any token that would be stuck on the contract as well.
-    function transferRewards(address token) external {
-        if (rewardsRecipient == address(0)) revert ErrorsLib.ZeroAddress();
+    /// @notice Skims the vault `token` balance to `skimRecipient`.
+    function skim(address token) external {
+        if (skimRecipient == address(0)) revert ErrorsLib.ZeroAddress();
 
         uint256 amount = IERC20(token).balanceOf(address(this));
-        if (token == asset()) amount -= idle;
 
-        SafeERC20.safeTransfer(IERC20(token), rewardsRecipient, amount);
+        SafeERC20.safeTransfer(IERC20(token), skimRecipient, amount);
 
-        emit EventsLib.TransferRewards(_msgSender(), rewardsRecipient, token, amount);
+        emit EventsLib.Skim(_msgSender(), skimRecipient, token, amount);
     }
 
     /* ERC4626 (PUBLIC) */
@@ -471,6 +460,18 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
         return ERC4626.decimals();
     }
 
+    /// @inheritdoc IERC4626
+    function maxDeposit(address) public view override(IERC4626, ERC4626) returns (uint256) {
+        return _maxSupply();
+    }
+
+    /// @inheritdoc IERC4626
+    function maxMint(address) public view override(IERC4626, ERC4626) returns (uint256) {
+        uint256 suppliable = _maxSupply();
+
+        return _convertToShares(suppliable, Math.Rounding.Floor);
+    }
+
     /// @inheritdoc IERC4626
     function maxWithdraw(address owner) public view override(IERC4626, ERC4626) returns (uint256 assets) {
         (assets,,) = _maxWithdraw(owner);
@@ -532,8 +533,6 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
         for (uint256 i; i < withdrawQueue.length; ++i) {
             assets += _supplyBalance(_marketParams(withdrawQueue[i]));
         }
-
-        assets += idle;
     }
 
     /* ERC4626 (INTERNAL) */
@@ -558,6 +557,14 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
         assets -= _staticWithdrawMorpho(assets);
     }
 
+    /// @dev Returns the maximum amount of assets that the vault can withdraw from Morpho.
+    function _maxSupply() internal view returns (uint256 totalSuppliable) {
+        for (uint256 i; i < supplyQueue.length; ++i) {
+            Id id = supplyQueue[i];
+            totalSuppliable += _suppliable(_marketParams(id), id);
+        }
+    }
+
     /// @inheritdoc ERC4626
     /// @dev The accrual of performance fees is taken into account in the conversion.
     function _convertToShares(uint256 assets, Math.Rounding rounding) internal view override returns (uint256) {
@@ -618,7 +625,7 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
         internal
         override
     {
-        if (_withdrawMorpho(assets) != 0) revert ErrorsLib.WithdrawMorphoFailed();
+        _withdrawMorpho(assets);
 
         super._withdraw(caller, receiver, owner, assets, shares);
 
@@ -703,7 +710,7 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
 
     /* LIQUIDITY ALLOCATION */
 
-    /// @dev Supplies `assets` to Morpho and increase the idle liquidity if necessary.
+    /// @dev Supplies `assets` to Morpho.
     function _supplyMorpho(uint256 assets) internal {
         for (uint256 i; i < supplyQueue.length; ++i) {
             Id id = supplyQueue[i];
@@ -721,40 +728,33 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
             if (assets == 0) return;
         }
 
-        idle += assets;
+        if (assets != 0) revert ErrorsLib.AllCapsReached();
     }
 
-    /// @dev Withdraws `assets` from the idle liquidity and Morpho if necessary.
-    /// @return remaining The assets left to be withdrawn.
-    function _withdrawMorpho(uint256 assets) internal returns (uint256 remaining) {
-        (remaining, idle) = _withdrawIdle(assets);
-
-        if (remaining == 0) return 0;
-
+    /// @dev Withdraws `assets` from Morpho.
+    function _withdrawMorpho(uint256 assets) internal {
         for (uint256 i; i < withdrawQueue.length; ++i) {
             Id id = withdrawQueue[i];
             MarketParams memory marketParams = _marketParams(id);
 
-            uint256 toWithdraw = UtilsLib.min(_withdrawable(marketParams, id), remaining);
+            uint256 toWithdraw = UtilsLib.min(_withdrawable(marketParams, id), assets);
 
             if (toWithdraw > 0) {
                 // Using try/catch to skip markets that revert.
                 try MORPHO.withdraw(marketParams, toWithdraw, 0, address(this), address(this)) {
-                    remaining -= toWithdraw;
+                    assets -= toWithdraw;
                 } catch {}
             }
 
-            if (remaining == 0) return 0;
+            if (assets == 0) return;
         }
-    }
 
-    /// @dev Fakes a withdraw of `assets` from the idle liquidity and Morpho if necessary.
-    /// @return remaining The assets left to be withdrawn.
-    function _staticWithdrawMorpho(uint256 assets) internal view returns (uint256 remaining) {
-        (remaining,) = _withdrawIdle(assets);
-
-        if (remaining == 0) return 0;
+        if (assets != 0) revert ErrorsLib.WithdrawMorphoFailed();
+    }
 
+    /// @dev Fakes a withdraw of `assets` from Morpho.
+    /// @return The assets left to be withdrawn.
+    function _staticWithdrawMorpho(uint256 assets) internal view returns (uint256) {
         for (uint256 i; i < withdrawQueue.length; ++i) {
             Id id = withdrawQueue[i];
             MarketParams memory marketParams = _marketParams(id);
@@ -763,17 +763,12 @@ contract MetaMorpho is ERC4626, ERC20Permit, Ownable2Step, Multicall, IMetaMorph
             // 1. oracle.price() is never called (the vault doesn't borrow)
             // 2. `_withdrawable` caps to the liquidity available on Morpho
             // 3. virtually accruing interest didn't fail in `_withdrawable`
-            remaining -= UtilsLib.min(_withdrawable(marketParams, id), remaining);
+            assets -= UtilsLib.min(_withdrawable(marketParams, id), assets);
 
-            if (remaining == 0) return 0;
+            if (assets == 0) break;
         }
-    }
 
-    /// @dev Withdraws `assets` from the idle liquidity.
-    /// @return The remaining assets to withdraw.
-    /// @return The new `idle` liquidity value.
-    function _withdrawIdle(uint256 assets) internal view returns (uint256, uint256) {
-        return (assets.zeroFloorSub(idle), idle.zeroFloorSub(assets));
+        return assets;
     }
 
     /// @dev Returns the suppliable amount of assets on the market defined by `marketParams`.

src/interfaces/IMetaMorpho.sol

@@ -44,15 +44,14 @@ interface IMetaMorpho is IERC4626 {
 
     function fee() external view returns (uint96);
     function feeRecipient() external view returns (address);
-    function rewardsRecipient() external view returns (address);
+    function skimRecipient() external view returns (address);
     function timelock() external view returns (uint256);
     function supplyQueue(uint256) external view returns (Id);
     function supplyQueueSize() external view returns (uint256);
     function withdrawQueue(uint256) external view returns (Id);
     function withdrawQueueSize() external view returns (uint256);
     function config(Id) external view returns (uint192 cap, uint64 withdrawRank);
 
-    function idle() external view returns (uint256);
     function lastTotalAssets() external view returns (uint256);
 
     function submitTimelock(uint256 newTimelock) external;
@@ -74,12 +73,12 @@ interface IMetaMorpho is IERC4626 {
     function revokeGuardian() external;
     function pendingGuardian() external view returns (address guardian, uint96 submittedAt);
 
-    function transferRewards(address) external;
+    function skim(address) external;
 
     function setIsAllocator(address newAllocator, bool newIsAllocator) external;
     function setCurator(address newCurator) external;
     function setFeeRecipient(address newFeeRecipient) external;
-    function setRewardsRecipient(address) external;
+    function setSkimRecipient(address) external;
 
     function setSupplyQueue(Id[] calldata newSupplyQueue) external;
     function sortWithdrawQueue(uint256[] calldata indexes) external;

src/libraries/ErrorsLib.sol

@@ -69,6 +69,9 @@ library ErrorsLib {
     /// @notice Thrown when setting the fee to a non zero value while the fee recipient is the zero address.
     error ZeroFeeRecipient();
 
-    /// @notice Thrown when the idle liquidity is insufficient to cover supply during a reallocation of funds.
-    error InsufficientIdle();
+    /// @notice Thrown when the amount withdrawn is not excatly the amount supplied.
+    error InconsistentReallocation();
+
+    /// @notice Thrown when all caps have been reached.
+    error AllCapsReached();
 }

src/libraries/EventsLib.sol

@@ -12,11 +12,11 @@ library EventsLib {
     /// @notice Emitted when a pending `newTimelock` is submitted.
     event SubmitTimelock(uint256 newTimelock);
 
-    /// @notice Emitted `timelock` is set to `newTimelock`.
+    /// @notice Emitted when `timelock` is set to `newTimelock`.
     event SetTimelock(uint256 newTimelock);
 
-    /// @notice Emitted `rewardsDistibutor` is set to `newRewardsRecipient`.
-    event SetRewardsRecipient(address indexed newRewardsRecipient);
+    /// @notice Emitted when `skimRecipient` is set to `newSkimRecipient`.
+    event SetSkimRecipient(address indexed newSkimRecipient);
 
     /// @notice Emitted when a pending `newFee` is submitted.
     event SubmitFee(uint256 newFee);
@@ -66,10 +66,8 @@ library EventsLib {
     /// @notice Emitted when fees are accrued.
     event AccrueFee(uint256 feeShares);
 
-    /// @notice Emitted when an `amount` of `token` is transferred to the `rewardsRecipient` by `caller`.
-    event TransferRewards(
-        address indexed caller, address indexed rewardsRecipient, address indexed token, uint256 amount
-    );
+    /// @notice Emitted when an `amount` of `token` is transferred to the `skimRecipient` by `caller`.
+    event Skim(address indexed caller, address indexed skimRecipient, address indexed token, uint256 amount);
 
     /// @notice Emitted when a new MetaMorpho vault is created.
     /// @param metaMorpho The address of the MetaMorpho vault.

test/forge/ERC4626A16zTest.sol

@@ -14,5 +14,7 @@ contract ERC4626A16zTest is IntegrationTest, ERC4626Test {
         _delta_ = 0;
         _vaultMayBeEmpty = true;
         _unlimitedAmount = true;
+
+        _setCap(allMarkets[0], 1e28);
     }
 }

test/forge/ERC4626Test.sol

@@ -87,26 +87,6 @@ contract ERC4626Test is IntegrationTest, IMorphoFlashLoanCallback {
         assertEq(vault.balanceOf(ONBEHALF), shares - redeemed, "balanceOf(ONBEHALF)");
     }
 
-    function testWithdrawIdle(uint256 deposited, uint256 withdrawn) public {
-        deposited = bound(deposited, MIN_TEST_ASSETS, MAX_TEST_ASSETS);
-        withdrawn = bound(withdrawn, 0, deposited);
-
-        _setCap(allMarkets[0], 0);
-
-        loanToken.setBalance(SUPPLIER, deposited);
-
-        vm.prank(SUPPLIER);
-        uint256 shares = vault.deposit(deposited, ONBEHALF);
-
-        vm.expectEmit();
-        emit EventsLib.UpdateLastTotalAssets(vault.totalAssets() - withdrawn);
-        vm.prank(ONBEHALF);
-        uint256 redeemed = vault.withdraw(withdrawn, RECEIVER, ONBEHALF);
-
-        assertEq(vault.balanceOf(ONBEHALF), shares - redeemed, "balanceOf(ONBEHALF)");
-        assertEq(vault.idle(), deposited - withdrawn, "idle");
-    }
-
     function testRedeemTooMuch(uint256 deposited) public {
         deposited = bound(deposited, MIN_TEST_ASSETS, MAX_TEST_ASSETS);
 
@@ -236,28 +216,15 @@ contract ERC4626Test is IntegrationTest, IMorphoFlashLoanCallback {
         vault.transferFrom(ONBEHALF, RECEIVER, shares);
     }
 
-    function testWithdrawMoreThanBalanceButLessThanTotalAssets(uint256 deposited, uint256 assets) public {
+    function testWithdrawMoreThanBalanceButLessThanTotalAssets(uint256 deposited) public {
         deposited = bound(deposited, MIN_TEST_ASSETS, MAX_TEST_ASSETS);
 
         loanToken.setBalance(SUPPLIER, deposited);
-
-        vm.prank(SUPPLIER);
-        uint256 shares = vault.deposit(deposited, ONBEHALF);
-
-        assets = bound(assets, deposited + 1, type(uint256).max / (deposited + 10 ** ConstantsLib.DECIMALS_OFFSET));
-
-        uint256 toAdd = assets - deposited + 1;
-        loanToken.setBalance(SUPPLIER, toAdd);
-
-        vm.prank(SUPPLIER);
-        vault.deposit(toAdd, SUPPLIER);
-
-        uint256 sharesBurnt = vault.previewWithdraw(assets);
-        vm.prank(ONBEHALF);
-        vm.expectRevert(
-            abi.encodeWithSelector(IERC20Errors.ERC20InsufficientBalance.selector, ONBEHALF, shares, sharesBurnt)
-        );
-        vault.withdraw(assets, RECEIVER, ONBEHALF);
+        vm.startPrank(SUPPLIER);
+        vault.deposit(deposited / 2, ONBEHALF);
+        vault.deposit(deposited / 2, SUPPLIER);
+        vm.expectRevert();
+        vault.withdraw(deposited, RECEIVER, SUPPLIER);
     }
 
     function testWithdrawMoreThanTotalAssets(uint256 deposited, uint256 assets) public {

test/forge/MetaMorphoFactoryTest.sol

@@ -14,7 +14,7 @@ contract MetaMorphoFactoryTest is IntegrationTest {
         factory = new MetaMorphoFactory(address(morpho));
     }
 
-    function testFactoryAddresssZero() public {
+    function testFactoryAddressZero() public {
         vm.expectRevert(ErrorsLib.ZeroAddress.selector);
         new MetaMorphoFactory(address(0));
     }