update BurnMintWithLockReleaseFlag to import the flag instead of rede…

…fining it for safety

contracts/gas-snapshots/ccip.gas-snapshot

@@ -30,7 +30,7 @@ BurnMintTokenPool_lockOrBurn:test_Setup_Success() (gas: 17851)
 BurnMintTokenPool_releaseOrMint:test_ChainNotAllowed_Revert() (gas: 28805)
 BurnMintTokenPool_releaseOrMint:test_PoolMintNotHealthy_Revert() (gas: 56253)
 BurnMintTokenPool_releaseOrMint:test_PoolMint_Success() (gas: 112391)
-BurnMintWithLockReleaseFlagTokenPool_lockOrBurn:test_PoolBurn_CorrectReturnData_Success() (gas: 242931)
+BurnMintWithLockReleaseFlagTokenPool_lockOrBurn:test_PoolBurn_CorrectReturnData_Success() (gas: 242252)
 BurnWithFromMintTokenPool_lockOrBurn:test_ChainNotAllowed_Revert() (gas: 28842)
 BurnWithFromMintTokenPool_lockOrBurn:test_PoolBurnRevertNotHealthy_Revert() (gas: 55271)
 BurnWithFromMintTokenPool_lockOrBurn:test_PoolBurn_Success() (gas: 244050)
@@ -425,38 +425,38 @@ FeeQuoter_validateDestFamilyAddress:test_InvalidEVMAddressPrecompiles_Revert() (
 FeeQuoter_validateDestFamilyAddress:test_InvalidEVMAddress_Revert() (gas: 10839)
 FeeQuoter_validateDestFamilyAddress:test_ValidEVMAddress_Success() (gas: 6731)
 FeeQuoter_validateDestFamilyAddress:test_ValidNonEVMAddress_Success() (gas: 6511)
-HybridUSDCTokenPoolMigrationTests:test_LockOrBurn_LockReleaseMechanism_then_switchToPrimary_Success() (gas: 209230)
-HybridUSDCTokenPoolMigrationTests:test_LockOrBurn_PrimaryMechanism_Success() (gas: 135861)
-HybridUSDCTokenPoolMigrationTests:test_LockOrBurn_WhileMigrationPause_Revert() (gas: 109814)
-HybridUSDCTokenPoolMigrationTests:test_LockOrBurn_onLockReleaseMechanism_Success() (gas: 147081)
-HybridUSDCTokenPoolMigrationTests:test_MintOrRelease_OnLockReleaseMechanism_Success() (gas: 217718)
-HybridUSDCTokenPoolMigrationTests:test_MintOrRelease_OnLockReleaseMechanism_then_switchToPrimary_Success() (gas: 426564)
-HybridUSDCTokenPoolMigrationTests:test_MintOrRelease_incomingMessageWithPrimaryMechanism() (gas: 268928)
-HybridUSDCTokenPoolMigrationTests:test_ProposeMigration_ChainNotUsingLockRelease_Revert() (gas: 15821)
-HybridUSDCTokenPoolMigrationTests:test_ReleaseOrMint_WhileMigrationPause_Revert() (gas: 114166)
-HybridUSDCTokenPoolMigrationTests:test_burnLockedUSDC_invalidPermissions_Revert() (gas: 39362)
-HybridUSDCTokenPoolMigrationTests:test_cancelExistingCCTPMigrationProposal() (gas: 56207)
-HybridUSDCTokenPoolMigrationTests:test_cannotCancelANonExistentMigrationProposal() (gas: 12736)
-HybridUSDCTokenPoolMigrationTests:test_cannotModifyLiquidityWithoutPermissions_Revert() (gas: 13373)
-HybridUSDCTokenPoolMigrationTests:test_cannotProvideLiquidityWhenMigrationProposalPending_Revert() (gas: 67304)
-HybridUSDCTokenPoolMigrationTests:test_cannotRevertChainMechanism_afterMigration_Revert() (gas: 313390)
-HybridUSDCTokenPoolMigrationTests:test_cannotTransferLiquidityDuringPendingMigration_Revert() (gas: 177033)
-HybridUSDCTokenPoolMigrationTests:test_cnanotProvideLiquidity_AfterMigration_Revert() (gas: 313775)
+HybridUSDCTokenPoolMigrationTests:test_LockOrBurn_LockReleaseMechanism_then_switchToPrimary_Success() (gas: 209283)
+HybridUSDCTokenPoolMigrationTests:test_LockOrBurn_PrimaryMechanism_Success() (gas: 135879)
+HybridUSDCTokenPoolMigrationTests:test_LockOrBurn_WhileMigrationPause_Revert() (gas: 109794)
+HybridUSDCTokenPoolMigrationTests:test_LockOrBurn_onLockReleaseMechanism_Success() (gas: 147082)
+HybridUSDCTokenPoolMigrationTests:test_MintOrRelease_OnLockReleaseMechanism_Success() (gas: 217024)
+HybridUSDCTokenPoolMigrationTests:test_MintOrRelease_OnLockReleaseMechanism_then_switchToPrimary_Success() (gas: 425913)
+HybridUSDCTokenPoolMigrationTests:test_MintOrRelease_incomingMessageWithPrimaryMechanism() (gas: 268945)
+HybridUSDCTokenPoolMigrationTests:test_ProposeMigration_ChainNotUsingLockRelease_Revert() (gas: 15843)
+HybridUSDCTokenPoolMigrationTests:test_ReleaseOrMint_WhileMigrationPause_Revert() (gas: 113503)
+HybridUSDCTokenPoolMigrationTests:test_burnLockedUSDC_invalidPermissions_Revert() (gas: 39300)
+HybridUSDCTokenPoolMigrationTests:test_cancelExistingCCTPMigrationProposal() (gas: 56208)
+HybridUSDCTokenPoolMigrationTests:test_cannotCancelANonExistentMigrationProposal() (gas: 12758)
+HybridUSDCTokenPoolMigrationTests:test_cannotModifyLiquidityWithoutPermissions_Revert() (gas: 13395)
+HybridUSDCTokenPoolMigrationTests:test_cannotProvideLiquidityWhenMigrationProposalPending_Revert() (gas: 67370)
+HybridUSDCTokenPoolMigrationTests:test_cannotRevertChainMechanism_afterMigration_Revert() (gas: 313252)
+HybridUSDCTokenPoolMigrationTests:test_cannotTransferLiquidityDuringPendingMigration_Revert() (gas: 177053)
+HybridUSDCTokenPoolMigrationTests:test_cnanotProvideLiquidity_AfterMigration_Revert() (gas: 313637)
 HybridUSDCTokenPoolMigrationTests:test_excludeTokensWhenNoMigrationProposalPending_Revert() (gas: 13657)
-HybridUSDCTokenPoolMigrationTests:test_lockOrBurn_then_BurnInCCTPMigration_Success() (gas: 309952)
-HybridUSDCTokenPoolMigrationTests:test_transferLiquidity_Success() (gas: 167124)
-HybridUSDCTokenPoolMigrationTests:test_unstickManualTxAfterMigration_destChain_Success() (gas: 156736)
-HybridUSDCTokenPoolMigrationTests:test_unstickManualTxAfterMigration_homeChain_Success() (gas: 516552)
-HybridUSDCTokenPoolTests:test_LockOrBurn_LockReleaseMechanism_then_switchToPrimary_Success() (gas: 209230)
-HybridUSDCTokenPoolTests:test_LockOrBurn_PrimaryMechanism_Success() (gas: 135880)
-HybridUSDCTokenPoolTests:test_LockOrBurn_WhileMigrationPause_Revert() (gas: 109814)
-HybridUSDCTokenPoolTests:test_LockOrBurn_onLockReleaseMechanism_Success() (gas: 147079)
-HybridUSDCTokenPoolTests:test_MintOrRelease_OnLockReleaseMechanism_Success() (gas: 217696)
-HybridUSDCTokenPoolTests:test_MintOrRelease_OnLockReleaseMechanism_then_switchToPrimary_Success() (gas: 426520)
-HybridUSDCTokenPoolTests:test_MintOrRelease_incomingMessageWithPrimaryMechanism() (gas: 268910)
-HybridUSDCTokenPoolTests:test_ReleaseOrMint_WhileMigrationPause_Revert() (gas: 114210)
-HybridUSDCTokenPoolTests:test_cannotTransferLiquidityDuringPendingMigration_Revert() (gas: 176989)
-HybridUSDCTokenPoolTests:test_transferLiquidity_Success() (gas: 167107)
+HybridUSDCTokenPoolMigrationTests:test_lockOrBurn_then_BurnInCCTPMigration_Success() (gas: 309797)
+HybridUSDCTokenPoolMigrationTests:test_transferLiquidity_Success() (gas: 167051)
+HybridUSDCTokenPoolMigrationTests:test_unstickManualTxAfterMigration_destChain_Success() (gas: 156096)
+HybridUSDCTokenPoolMigrationTests:test_unstickManualTxAfterMigration_homeChain_Success() (gas: 515988)
+HybridUSDCTokenPoolTests:test_LockOrBurn_LockReleaseMechanism_then_switchToPrimary_Success() (gas: 209283)
+HybridUSDCTokenPoolTests:test_LockOrBurn_PrimaryMechanism_Success() (gas: 135897)
+HybridUSDCTokenPoolTests:test_LockOrBurn_WhileMigrationPause_Revert() (gas: 109794)
+HybridUSDCTokenPoolTests:test_LockOrBurn_onLockReleaseMechanism_Success() (gas: 147080)
+HybridUSDCTokenPoolTests:test_MintOrRelease_OnLockReleaseMechanism_Success() (gas: 217002)
+HybridUSDCTokenPoolTests:test_MintOrRelease_OnLockReleaseMechanism_then_switchToPrimary_Success() (gas: 425869)
+HybridUSDCTokenPoolTests:test_MintOrRelease_incomingMessageWithPrimaryMechanism() (gas: 268928)
+HybridUSDCTokenPoolTests:test_ReleaseOrMint_WhileMigrationPause_Revert() (gas: 113547)
+HybridUSDCTokenPoolTests:test_cannotTransferLiquidityDuringPendingMigration_Revert() (gas: 177009)
+HybridUSDCTokenPoolTests:test_transferLiquidity_Success() (gas: 167033)
 LockReleaseTokenPoolAndProxy_setRebalancer:test_SetRebalancer_Revert() (gas: 10989)
 LockReleaseTokenPoolAndProxy_setRebalancer:test_SetRebalancer_Success() (gas: 18028)
 LockReleaseTokenPoolPoolAndProxy_canAcceptLiquidity:test_CanAcceptLiquidity_Success() (gas: 3051552)

contracts/src/v0.8/ccip/pools/USDC/BurnMintWithLockReleaseFlagTokenPool.sol

@@ -5,16 +5,14 @@ import {IBurnMintERC20} from "../../../shared/token/ERC20/IBurnMintERC20.sol";
 
 import {Pool} from "../../libraries/Pool.sol";
 import {BurnMintTokenPool} from "../BurnMintTokenPool.sol";
+import {LOCK_RELEASE_FLAG} from "./HybridLockReleaseUSDCTokenPool.sol";
 
 /// @notice A standard BurnMintTokenPool with modified destPoolData so that the remote pool knows to release tokens
 /// instead of minting. This enables interoperability with HybridLockReleaseUSDCTokenPool which uses
 // the destPoolData to determine whether to mint or release tokens.
 /// @dev The only difference between this contract and BurnMintTokenPool is the destPoolData returns the
 /// abi-encoded LOCK_RELEASE_FLAG instead of an empty string.
 contract BurnMintWithLockReleaseFlagTokenPool is BurnMintTokenPool {
-  /// bytes4(keccak256("NO_CCTP_USE_LOCK_RELEASE"))
-  bytes4 public constant LOCK_RELEASE_FLAG = 0xfa7c07de;
-
   constructor(
     IBurnMintERC20 token,
     address[] memory allowlist,
@@ -24,6 +22,8 @@ contract BurnMintWithLockReleaseFlagTokenPool is BurnMintTokenPool {
 
   /// @notice Burn the token in the pool
   /// @dev The _validateLockOrBurn check is an essential security check
+  /// @dev Performs the exact same functionality as BurnMintTokenPool, but returns the LOCK_RELEASE_FLAG
+  /// as the destPoolData to signal to the remote pool to release tokens instead of minting them.
   function lockOrBurn(
     Pool.LockOrBurnInV1 calldata lockOrBurnIn
   ) external override returns (Pool.LockOrBurnOutV1 memory) {
@@ -33,6 +33,7 @@ contract BurnMintWithLockReleaseFlagTokenPool is BurnMintTokenPool {
 
     emit Burned(msg.sender, lockOrBurnIn.amount);
 
+    // LOCK_RELEASE_FLAG = bytes4(keccak256("NO_CCTP_USE_LOCK_RELEASE"))
     return Pool.LockOrBurnOutV1({
       destTokenAddress: getRemoteToken(lockOrBurnIn.remoteChainSelector),
       destPoolData: abi.encode(LOCK_RELEASE_FLAG)

contracts/src/v0.8/ccip/pools/USDC/HybridLockReleaseUSDCTokenPool.sol

@@ -14,6 +14,9 @@ import {IERC20} from "../../../vendor/openzeppelin-solidity/v4.8.3/contracts/tok
 import {SafeERC20} from "../../../vendor/openzeppelin-solidity/v4.8.3/contracts/token/ERC20/utils/SafeERC20.sol";
 import {EnumerableSet} from "../../../vendor/openzeppelin-solidity/v4.8.3/contracts/utils/structs/EnumerableSet.sol";
 
+// bytes4(keccak256("NO_CCTP_USE_LOCK_RELEASE"))
+bytes4 constant LOCK_RELEASE_FLAG = 0xfa7c07de;
+
 /// @notice A token pool for USDC which uses CCTP for supported chains and Lock/Release for all others
 /// @dev The functionality from LockReleaseTokenPool.sol has been duplicated due to lack of compiler support for shared
 /// constructors between parents
@@ -34,9 +37,6 @@ contract HybridLockReleaseUSDCTokenPool is USDCTokenPool, USDCBridgeMigrator {
   error LanePausedForCCTPMigration(uint64 remoteChainSelector);
   error TokenLockingNotAllowedAfterMigration(uint64 remoteChainSelector);
 
-  /// bytes4(keccak256("NO_CCTP_USE_LOCK_RELEASE"))
-  bytes4 public constant LOCK_RELEASE_FLAG = 0xfa7c07de;
-
   /// @notice The address of the liquidity provider for a specific chain.
   /// External liquidity is not required when there is one canonical token deployed to a chain,
   /// and CCIP is facilitating mint/burn on all the other chains, in which case the invariant

contracts/src/v0.8/ccip/test/pools/BurnMintWithLockReleaseFlagTokenPool.t.sol

@@ -5,6 +5,8 @@ import {Pool} from "../../libraries/Pool.sol";
 import {RateLimiter} from "../../libraries/RateLimiter.sol";
 import {TokenPool} from "../../pools/TokenPool.sol";
 import {BurnMintWithLockReleaseFlagTokenPool} from "../../pools/USDC/BurnMintWithLockReleaseFlagTokenPool.sol";
+
+import {LOCK_RELEASE_FLAG} from "../../pools/USDC/HybridLockReleaseUSDCTokenPool.sol";
 import {BurnMintSetup} from "./BurnMintSetup.t.sol";
 
 import {IERC20} from "../../../vendor/openzeppelin-solidity/v4.8.3/contracts/token/ERC20/IERC20.sol";
@@ -57,6 +59,6 @@ contract BurnMintWithLockReleaseFlagTokenPool_lockOrBurn is BurnMintWithLockRele
 
     assertEq(s_burnMintERC677.balanceOf(address(s_pool)), 0);
 
-    assertEq(bytes4(lockOrBurnOut.destPoolData), s_pool.LOCK_RELEASE_FLAG());
+    assertEq(bytes4(lockOrBurnOut.destPoolData), LOCK_RELEASE_FLAG);
   }
 }

contracts/src/v0.8/ccip/test/pools/HybridLockReleaseUSDCTokenPool.t.sol

@@ -14,6 +14,7 @@ import {RateLimiter} from "../../libraries/RateLimiter.sol";
 
 import {TokenPool} from "../../pools/TokenPool.sol";
 import {HybridLockReleaseUSDCTokenPool} from "../../pools/USDC/HybridLockReleaseUSDCTokenPool.sol";
+import {LOCK_RELEASE_FLAG} from "../../pools/USDC/HybridLockReleaseUSDCTokenPool.sol";
 import {USDCBridgeMigrator} from "../../pools/USDC/USDCBridgeMigrator.sol";
 import {USDCTokenPool} from "../../pools/USDC/USDCTokenPool.sol";
 import {BaseTest} from "../BaseTest.t.sol";
@@ -224,7 +225,7 @@ contract HybridUSDCTokenPoolTests is USDCTokenPoolSetup {
         localToken: address(s_token),
         remoteChainSelector: SOURCE_CHAIN_SELECTOR,
         sourcePoolAddress: sourceTokenData.sourcePoolAddress,
-        sourcePoolData: abi.encode(s_usdcTokenPool.LOCK_RELEASE_FLAG()),
+        sourcePoolData: abi.encode(LOCK_RELEASE_FLAG),
         offchainTokenData: ""
       })
     );
@@ -442,7 +443,7 @@ contract HybridUSDCTokenPoolTests is USDCTokenPoolSetup {
       destGasAmount: USDC_DEST_TOKEN_GAS
     });
 
-    bytes memory sourcePoolDataLockRelease = abi.encode(s_usdcTokenPool.LOCK_RELEASE_FLAG());
+    bytes memory sourcePoolDataLockRelease = abi.encode(LOCK_RELEASE_FLAG);
 
     uint256 amount = 1e6;
 
@@ -757,7 +758,7 @@ contract HybridUSDCTokenPoolMigrationTests is HybridUSDCTokenPoolTests {
         localToken: address(s_token),
         remoteChainSelector: SOURCE_CHAIN_SELECTOR,
         sourcePoolAddress: sourceTokenData.sourcePoolAddress,
-        sourcePoolData: abi.encode(s_usdcTokenPool.LOCK_RELEASE_FLAG()),
+        sourcePoolData: abi.encode(LOCK_RELEASE_FLAG),
         offchainTokenData: ""
       })
     );
@@ -876,7 +877,7 @@ contract HybridUSDCTokenPoolMigrationTests is HybridUSDCTokenPoolTests {
         localToken: address(s_token),
         remoteChainSelector: SOURCE_CHAIN_SELECTOR,
         sourcePoolAddress: sourceTokenData.sourcePoolAddress,
-        sourcePoolData: abi.encode(s_usdcTokenPool.LOCK_RELEASE_FLAG()),
+        sourcePoolData: abi.encode(LOCK_RELEASE_FLAG),
         offchainTokenData: ""
       })
     );