Add a SafeERC20:safePermit function (#3280)

contracts/mocks/SafeERC20Helper.sol

@@ -4,6 +4,7 @@ pragma solidity ^0.8.0;
 
 import "../utils/Context.sol";
 import "../token/ERC20/IERC20.sol";
+import "../token/ERC20/extensions/draft-ERC20Permit.sol";
 import "../token/ERC20/utils/SafeERC20.sol";
 
 contract ERC20ReturnFalseMock is Context {
@@ -105,6 +106,43 @@ contract ERC20NoReturnMock is Context {
     }
 }
 
+contract ERC20PermitNoRevertMock is
+    ERC20("ERC20PermitNoRevertMock", "ERC20PermitNoRevertMock"),
+    ERC20Permit("ERC20PermitNoRevertMock")
+{
+    function getChainId() external view returns (uint256) {
+        return block.chainid;
+    }
+
+    function permitThatMayRevert(
+        address owner,
+        address spender,
+        uint256 value,
+        uint256 deadline,
+        uint8 v,
+        bytes32 r,
+        bytes32 s
+    ) public virtual {
+        super.permit(owner, spender, value, deadline, v, r, s);
+    }
+
+    function permit(
+        address owner,
+        address spender,
+        uint256 value,
+        uint256 deadline,
+        uint8 v,
+        bytes32 r,
+        bytes32 s
+    ) public virtual override {
+        try this.permitThatMayRevert(owner, spender, value, deadline, v, r, s) {
+            // do nothing
+        } catch {
+            // do nothing
+        }
+    }
+}
+
 contract SafeERC20Wrapper is Context {
     using SafeERC20 for IERC20;
 
@@ -134,6 +172,18 @@ contract SafeERC20Wrapper is Context {
         _token.safeDecreaseAllowance(address(0), amount);
     }
 
+    function permit(
+        address owner,
+        address spender,
+        uint256 value,
+        uint256 deadline,
+        uint8 v,
+        bytes32 r,
+        bytes32 s
+    ) public {
+        SafeERC20.safePermit(IERC20Permit(address(_token)), owner, spender, value, deadline, v, r, s);
+    }
+
     function setAllowance(uint256 allowance_) public {
         ERC20ReturnTrueMock(address(_token)).setAllowance(allowance_);
     }

contracts/token/ERC20/utils/SafeERC20.sol

@@ -4,6 +4,7 @@
 pragma solidity ^0.8.0;
 
 import "../IERC20.sol";
+import "../extensions/draft-IERC20Permit.sol";
 import "../../../utils/Address.sol";
 
 /**
@@ -79,6 +80,22 @@ library SafeERC20 {
         }
     }
 
+    function safePermit(
+        IERC20Permit token,
+        address owner,
+        address spender,
+        uint256 value,
+        uint256 deadline,
+        uint8 v,
+        bytes32 r,
+        bytes32 s
+    ) internal {
+        uint256 nonceBefore = token.nonces(owner);
+        token.permit(owner, spender, value, deadline, v, r, s);
+        uint256 nonceAfter = token.nonces(owner);
+        require(nonceAfter == nonceBefore + 1, "SafeERC20: permit did not succeed");
+    }
+
     /**
      * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
      * on the return value: the return value is optional (but if data is returned, it must not be false).