Update SpokePool.sol

Author: nicholaspai

contracts/SpokePool.sol

@@ -60,7 +60,12 @@ abstract contract SpokePool is
     WETH9Interface private DEPRECATED_wrappedNativeToken;
     uint32 private DEPRECATED_depositQuoteTimeBuffer;
 
-    // Count of deposits is used to construct a unique deposit identifier for this spoke pool.
+    // Count of deposits is used to construct a unique deposit identifier for this spoke pool. This value
+    // gets emitted and incremented on each depositV3 call. Because its a uint32, it will get implicitly cast to
+    // uint256 in the emitted V3FundsDeposited event by setting its most significant bits to 0.
+    // This variable name `numberOfDeposits` should ideally be re-named to
+    // depositNonceCounter or something similar because its not a true representation of the number of deposits
+    // because `unsafeDepositV3` can be called directly and bypass this increment.
     uint32 public numberOfDeposits;
 
     // Whether deposits and fills are disabled.
@@ -514,6 +519,13 @@ abstract contract SpokePool is
         uint32 exclusivityParameter,
         bytes calldata message
     ) public payable override nonReentrant unpausedDeposits {
+        // Increment deposit nonce variable `numberOfDeposits` so that deposit ID for this deposit on this
+        // spoke pool is unique. This variable `numberOfDeposits` should ideally be re-named to
+        // depositNonceCounter or something similar because its not a true representation of the number of deposits
+        // because `unsafeDepositV3` can be called directly and bypass this increment.
+        // The `numberOfDeposits` is a uint32 that will get implicitly cast to uint256 by setting the
+        // most significant bits to 0, which creates very little chance this an unsafe deposit ID collides
+        // with a safe deposit ID.
         DepositV3Params memory params = DepositV3Params({
             depositor: depositor,
             recipient: recipient,