Forbid most uses of msg.sender in favor of _msgSender()

src/Context.sol

@@ -1,16 +1,24 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.21;
 
-abstract contract Context {
-    function _msgSender() internal view virtual returns (address) {
+abstract contract ContextAbstract {
+    function _msgSender() internal view virtual returns (address);
+
+    function _msgData() internal view virtual returns (bytes calldata);
+
+    function _isForwarded() internal view virtual returns (bool);
+}
+
+abstract contract Context is ContextAbstract {
+    function _msgSender() internal view virtual override returns (address) {
         return msg.sender;
     }
 
-    function _msgData() internal view virtual returns (bytes calldata) {
+    function _msgData() internal view virtual override returns (bytes calldata) {
         return msg.data;
     }
 
-    function _isForwarded() internal view virtual returns (bool) {
+    function _isForwarded() internal view virtual override returns (bool) {
         return false;
     }
 }

src/Settler.sol

@@ -180,15 +180,15 @@ contract Settler is Permit2Payment, Basic, OtcOrderSettlement, UniswapV3, Uniswa
                     bytes memory sig
                 ) = abi.decode(data, (address, uint256, uint256, bytes, ISignatureTransfer.PermitTransferFrom, bytes));
 
-                sellTokenForTokenToUniswapV3(path, amountIn, amountOutMin, recipient, msg.sender, permit, sig);
+                sellTokenForTokenToUniswapV3(path, amountIn, amountOutMin, recipient, _msgSender(), permit, sig);
             } else {
-                _dispatch(0, action, data, msg.sender);
+                _dispatch(0, action, data, _msgSender());
             }
         }
 
         for (uint256 i = 1; i < actions.length; i = i.unsafeInc()) {
             (bytes4 action, bytes calldata data) = actions.decodeCall(i);
-            _dispatch(i, action, data, msg.sender);
+            _dispatch(i, action, data, _msgSender());
         }
 
         _checkSlippageAndTransfer(slippage);

src/core/OtcOrderSettlement.sol

@@ -128,18 +128,18 @@ abstract contract OtcOrderSettlement is Permit2PaymentAbstract {
         ISignatureTransfer.SignatureTransferDetails memory takerTransferDetails;
         Consideration memory consideration;
         (takerTransferDetails, consideration.token, consideration.amount) = _permitToTransferDetails(takerPermit, maker);
-        consideration.counterparty = msg.sender;
+        consideration.counterparty = _msgSender();
 
         bytes32 witness = _hashConsideration(consideration);
         // There is no taker witness (see below)
 
         // Maker pays recipient (optional fee)
         _permit2TransferFrom(makerPermit, makerTransferDetails, maker, witness, CONSIDERATION_WITNESS, makerSig);
         // Taker pays Maker (optional fee)
-        // We don't need to include a witness here. Taker is `msg.sender`, so
+        // We don't need to include a witness here. Taker is `_msgSender()`, so
         // `recipient` and the maker's details are already authenticated. We're just
         // using PERMIT2 to move tokens, not to provide authentication.
-        _permit2TransferFrom(takerPermit, takerTransferDetails, msg.sender, takerSig);
+        _permit2TransferFrom(takerPermit, takerTransferDetails, _msgSender(), takerSig);
 
         emit OtcOrderFilled(
             _hashOtcOrder(
@@ -149,7 +149,7 @@ abstract contract OtcOrderSettlement is Permit2PaymentAbstract {
                 )
             ),
             maker,
-            msg.sender,
+            _msgSender(),
             buyToken,
             consideration.token,
             buyAmount,

src/core/Permit2Payment.sol

@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: MIT
 pragma solidity ^0.8.21;
 
+import {ContextAbstract} from "../Context.sol";
 import {AllowanceHolderContext} from "../AllowanceHolderContext.sol";
 import {AllowanceHolder} from "../AllowanceHolder.sol";
 
@@ -40,7 +41,7 @@ library UnsafeArray {
     }
 }
 
-abstract contract Permit2PaymentAbstract {
+abstract contract Permit2PaymentAbstract is ContextAbstract {
     string internal constant TOKEN_PERMISSIONS_TYPE = "TokenPermissions(address token,uint256 amount)";
 
     function PERMIT2() internal view virtual returns (ISignatureTransfer);