Fixes dust balance handling for pallet revive (#9357)

fix issue: paritytech/contract-issues#141

Corrects the condition for minting a new currency unit when transferring
dust. The condition was incorrectly checking
`to_info.dust.saturating_add(dust) >= plank` which could lead to
unexpected minting behavior. It now correctly checks if `to_info.dust >=
plank` before minting.

Author: sekisamu

prdoc/pr_9357.prdoc

@@ -0,0 +1,11 @@
+title: "Fix dust balance handling in ETH transfers"
+
+doc:
+  - audience: Runtime Dev
+    description: |-
+      Fixed a bug in the eth-decimals implementation where ETH transfers were failing due to incorrect receiver dust balance handling. The condition for minting a new currency unit when transferring dust was checking `to_info.dust.saturating_add(dust) >= plank` which `to_info.dust` has been added twice, could lead to unexpected minting behavior.
+      This fix ensures that ETH transfers work correctly, enabling proper operation of DeFi protocols like Uniswap on PolkaVM.
+
+crates:
+  - name: pallet-revive
+    bump: patch

substrate/frame/revive/src/exec.rs

@@ -1443,7 +1443,7 @@ where
 			transfer_balance::<T>(from, to, value)?;
 			transfer_dust::<T>(&mut from_info, &mut to_info, dust)?;
 
-			if to_info.dust.saturating_add(dust) >= plank {
+			if to_info.dust >= plank {
 				T::Currency::mint_into(to, 1u32.into())?;
 				to_info.dust =
 					to_info.dust.checked_sub(plank).ok_or_else(|| Error::<T>::TransferFailed)?;

substrate/frame/revive/src/tests.rs

@@ -518,6 +518,15 @@ fn transfer_with_dust_works() {
 			expected_to_balance: BalanceWithDust::new_unchecked::<Test>(2, 0),
 			total_issuance_diff: -1,
 		},
+		TestCase {
+			description: "receiver dust less than 1 plank",
+			from_balance: BalanceWithDust::new_unchecked::<Test>(100, plank / 10),
+			to_balance: BalanceWithDust::new_unchecked::<Test>(0, plank / 2),
+			amount: BalanceWithDust::new_unchecked::<Test>(1, plank / 10 * 3),
+			expected_from_balance: BalanceWithDust::new_unchecked::<Test>(98, plank / 10 * 8),
+			expected_to_balance: BalanceWithDust::new_unchecked::<Test>(1, plank / 10 * 8),
+			total_issuance_diff: 1,
+		},
 	];
 
 	for TestCase {