Merge branch 'main' into bound-fees-upper-limit

solidity/contracts/lib/ERC4626Fees.sol

@@ -84,6 +84,13 @@ abstract contract ERC4626Fees is ERC4626Upgradeable {
         }
     }
 
+    /// @dev Calculate the maximum amount of assets that can be withdrawn
+    ///      by an account including fees. See {IERC4626-maxWithdraw}.
+    function _maxWithdraw(address account) internal view returns (uint256) {
+        uint256 maxAssets = super.maxWithdraw(account);
+        return maxAssets - _feeOnTotal(maxAssets, _exitFeeBasisPoints());
+    }
+
     // === Fee configuration ===
 
     // slither-disable-next-line dead-code

solidity/contracts/stBTC.sol

@@ -331,7 +331,7 @@ contract stBTC is ERC4626Fees, PausableOwnable {
         if (paused()) {
             return 0;
         }
-        return super.maxWithdraw(owner);
+        return _maxWithdraw(owner);
     }
 
     /// @dev Returns the maximum amount of Vault shares that can be redeemed from

solidity/test/stBTC.test.ts

@@ -2172,6 +2172,50 @@ describe("stBTC", () => {
     })
   })
 
+  describe("maxWithdraw", () => {
+    beforeAfterSnapshotWrapper()
+    const amountToDeposit = to1e18(1)
+    let expectedDepositedAmount: bigint
+    let expectedWithdrawnAmount: bigint
+
+    before(async () => {
+      await tbtc
+        .connect(depositor1)
+        .approve(await stbtc.getAddress(), amountToDeposit)
+      await stbtc
+        .connect(depositor1)
+        .deposit(amountToDeposit, depositor1.address)
+      expectedDepositedAmount =
+        amountToDeposit - feeOnTotal(amountToDeposit, entryFeeBasisPoints)
+      expectedWithdrawnAmount =
+        expectedDepositedAmount -
+        feeOnTotal(expectedDepositedAmount, exitFeeBasisPoints)
+    })
+
+    it("should account for the exit fee", async () => {
+      const maxWithdraw = await stbtc.maxWithdraw(depositor1.address)
+
+      expect(maxWithdraw).to.be.eq(expectedWithdrawnAmount)
+    })
+
+    it("should be equal to the actual redeemable amount", async () => {
+      const maxWithdraw = await stbtc.maxWithdraw(depositor1.address)
+      const availableShares = await stbtc.balanceOf(depositor1.address)
+
+      const tx = await stbtc.redeem(
+        availableShares,
+        depositor1.address,
+        depositor1.address,
+      )
+
+      await expect(tx).to.changeTokenBalances(
+        tbtc,
+        [depositor1.address],
+        [maxWithdraw],
+      )
+    })
+  })
+
   describe("feeOnTotal - internal test helper", () => {
     context("when the fee's modulo remainder is greater than 0", () => {
       it("should add 1 to the result", () => {