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Submission Details
Severity: gas
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# `_burnDsc` function on `DSCEngine` can be simplified

LaScaloneta

Summary

_burnDsc function on DSCEngine can be simplified to avoid extra calls.

Vulnerability Details

Instead of doing a transfer and a burn, you can just use burnFrom.

Impact

Gas impact Overall gas change: -336291 (-2.229%)

testRevertsIfTokenLengthDoesntMatchPriceFeeds() (gas: -40 (-0.022%))
testRevertsIfMintFails() (gas: -36694 (-1.805%))
testRevertsIfTransferFromFails() (gas: -36694 (-1.876%))
testRevertsIfTransferFails() (gas: -36694 (-1.901%))
testMustImproveHealthFactorOnLiquidation() (gas: -81010 (-3.427%))
testUserStillHasSomeEthAfterLiquidation() (gas: -20737 (-4.160%))
testLiquidationPayoutIsCorrect() (gas: -20737 (-4.281%))
testLiquidatorTakesOnUsersDebt() (gas: -20737 (-4.289%))
testUserHasNoMoreDebt() (gas: -20737 (-4.290%))
testCanRedeemDepositedCollateral() (gas: -20737 (-8.240%))
testCanBurnDsc() (gas: -20737 (-8.739%))
testMustRedeemMoreThanZero() (gas: -20737 (-8.751%))
Overall gas change: -336291 (-2.229%)

Tools Used

Manual revision

Recommendations

diff --git a/src/DSCEngine.sol b/src/DSCEngine.sol
index a7a6639..1906a92 100644
--- a/src/DSCEngine.sol
+++ b/src/DSCEngine.sol
@@ -271,12 +271,7 @@ contract DSCEngine is ReentrancyGuard {
*/
function _burnDsc(uint256 amountDscToBurn, address onBehalfOf, address dscFrom) private {
s_DSCMinted[onBehalfOf] -= amountDscToBurn;
- bool success = i_dsc.transferFrom(dscFrom, address(this), amountDscToBurn);
- // This conditional is hypothtically unreachable
- if (!success) {
- revert DSCEngine__TransferFailed();
- }
- i_dsc.burn(amountDscToBurn);
+ i_dsc.burnFrom(dscFrom, amountDscToBurn);
}
function _redeemCollateral(address from, address to, address tokenCollateralAddress, uint256 amountCollateral)

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