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taikoxyz · May 9, 2024 · a0d4b61 · a0d4b61
1 parent 0d7a806
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Showing 2 changed files with 12 additions and 29 deletions.
diff --git a/packages/protocol/contracts/tokenvault/BridgedERC20.sol b/packages/protocol/contracts/tokenvault/BridgedERC20.sol
@@ -49,6 +49,7 @@ contract BridgedERC20 is EssentialContract, IBridgedERC20, ERC20Upgradeable {
     error BTOKEN_INVALID_PARAMS();
     error BTOKEN_INVALID_TO_ADDR();
     error BTOKEN_MINT_DISALLOWED();
+    error BTOKEN_BURN_DISALLOWED();
 
     /// @notice Initializes the contract.
     /// @param _owner The owner of this contract. msg.sender will be used if this value is zero.
@@ -115,29 +116,25 @@ contract BridgedERC20 is EssentialContract, IBridgedERC20, ERC20Upgradeable {
             emit MigratedFrom(_migratingAddress, _account, _amount);
         } else {
             // Bridging from vault
-            _authorizedMintBurn(msg.sender);
+            _authorizedMint(msg.sender);
         }
 
         _mint(_account, _amount);
     }
 
-    /// @notice Burns tokens in case of 'migrating out' from msg.sender (EOA) or from the ERC20Vault
-    /// if bridging back to canonical token.
+    /// @notice Burns tokens in case of 'migrating out' from msg.sender.
     /// @param _amount The amount of tokens to burn.
     function burn(uint256 _amount) external whenNotPaused nonReentrant {
-        if (isMigratingOut()) {
-            // Outbound migration
-            address _migratingAddress = migratingAddress;
-            emit MigratedTo(_migratingAddress, msg.sender, _amount);
-            // Ask the new bridged token to mint token for the user.
-            IBridgedERC20(_migratingAddress).mint(msg.sender, _amount);
-        } else {
-            // When user wants to burn tokens only during 'migrating out' phase is possible. If
-            // ERC20Vault burns the tokens, that will go through the burn(amount) function.
-            _authorizedMintBurn(msg.sender);
-        }
+        if (!isMigratingOut()) revert BTOKEN_BURN_DISALLOWED();
+
+        // Outbound migration
+        address _migratingAddress = migratingAddress;
 
         _burn(msg.sender, _amount);
+
+        emit MigratedTo(_migratingAddress, msg.sender, _amount);
+        // Ask the new bridged token to mint token for the user.
+        IBridgedERC20(_migratingAddress).mint(msg.sender, _amount);
     }
 
     /// @dev Transfers tokens then burn.
@@ -192,8 +189,5 @@ contract BridgedERC20 is EssentialContract, IBridgedERC20, ERC20Upgradeable {
         return super._beforeTokenTransfer(_from, _to, _amount);
     }
 
-    function _authorizedMintBurn(address addr)
-        private
-        onlyFromOwnerOrNamed(LibStrings.B_ERC20_VAULT)
-    { }
+    function _authorizedMint(address addr) private onlyFromOwnerOrNamed(LibStrings.B_ERC20_VAULT) { }
 }
diff --git a/packages/protocol/test/tokenvault/BridgedERC20.t.sol b/packages/protocol/test/tokenvault/BridgedERC20.t.sol
@@ -99,12 +99,6 @@ contract TestBridgedERC20 is TaikoTest {
         newToken.mint(Bob, 15);
         assertEq(newToken.balanceOf(Bob), 235);
 
-        // Vault can only burn if it owns the tokens
-        vm.prank(vault);
-        vm.expectRevert();
-        newToken.burn(25);
-        assertEq(newToken.balanceOf(Bob), 235);
-
         // Imitate current bridge-back operation, as Bob gave approval (for bridging back) and then
         // ERC20Vault does the "transfer and burn"
         vm.prank(Bob);
@@ -113,11 +107,6 @@ contract TestBridgedERC20 is TaikoTest {
         // Following the "transfer and burn" pattern
         vm.prank(vault);
         newToken.transferFrom(Bob, vault, 25);
-
-        vm.prank(vault);
-        newToken.burn(25);
-
-        assertEq(newToken.balanceOf(Bob), 210);
     }
 
     function deployBridgedToken(string memory name) internal returns (BridgedERC20) {