evm: Add makeCCTPv2Request

Author: bruce-riley

evm/README.md

@@ -94,6 +94,31 @@ executor.requestExecution{value: executorArgs.value}(
 
 <!-- cspell:enable -->
 
+#### Example v2 CCTP Request
+
+The `depositForBurn` function in CCTP v2 doesn't return anything, so we don't have a unique identifier for a transfer.
+The off-chain executor will detect all Circle V2 transfers in the transaction and relay them.
+
+<!-- cspell:disable -->
+
+```solidity
+import "example-messaging-executor/evm/src/interfaces/IExecutor.sol";
+import "example-messaging-executor/evm/src/libraries/ExecutorMessages.sol";
+...
+circleTokenMessenger.depositForBurn(amount, destinationDomain, mintRecipient, burnToken, destinationCaller, maxFee, minFinalityThreshold);
+
+executor.requestExecution{value: executorArgs.value}(
+    0,
+    bytes32(0),
+    executorArgs.refundAddress,
+    executorArgs.signedQuote,
+    ExecutorMessages.makeCCTPv2Request(),
+    executorArgs.instructions
+);
+```
+
+<!-- cspell:enable -->
+
 ### Execution Support
 
 #### v1 VAA Execution

evm/src/libraries/ExecutorMessages.sol

@@ -6,6 +6,7 @@ library ExecutorMessages {
     bytes4 private constant REQ_VAA_V1 = "ERV1";
     bytes4 private constant REQ_NTT_V1 = "ERN1";
     bytes4 private constant REQ_CCTP_V1 = "ERC1";
+    bytes4 private constant REQ_CCTP_V2 = "ERC2";
 
     /// @notice Payload length will not fit in a uint32.
     /// @dev Selector: 492f620d.
@@ -63,4 +64,12 @@ library ExecutorMessages {
     function makeCCTPv1Request(uint32 sourceDomain, uint64 nonce) internal pure returns (bytes memory) {
         return abi.encodePacked(REQ_CCTP_V1, sourceDomain, nonce);
     }
+
+    /// @notice Encodes a version 2 CCTP request payload.
+    ///         This request currently assumes the Executor will auto detect the event off chain.
+    ///         That may change in the future, in which case this interface would change.
+    /// @return bytes The encoded request.
+    function makeCCTPv2Request() internal pure returns (bytes memory) {
+        return abi.encodePacked(REQ_CCTP_V2, uint8(1));
+    }
 }

evm/test/ExecutorMessages.t.sol

@@ -46,4 +46,10 @@ contract ExecutorMessagesTest is Test {
         bytes memory buf = ExecutorMessages.makeCCTPv1Request(srcDomain, nonce);
         assertEq(keccak256(expected), keccak256(buf));
     }
+
+    function test_makeCCTPv2Request() public pure {
+        bytes memory expected = abi.encodePacked("ERC2", uint8(1));
+        bytes memory buf = ExecutorMessages.makeCCTPv2Request();
+        assertEq(keccak256(expected), keccak256(buf));
+    }
 }