fix: correct fee calculation for exactOut swaps in afterSwap example #1109
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The afterSwap hook fee example incorrectly calculated the fee amount using outputAmount for both exactIn and exactOut swaps. However, as noted in the documentation tip, the returned int128 is for the unspecified currency: - exactIn: unspecified = output token - exactOut: unspecified = input token The previous code always used outputAmount to compute feeAmount, which is incorrect for exactOut swaps where the fee should be calculated from the input amount. This fix: - Determines the unspecified token based on swap type - Uses the correct amount (output for exactIn, input for exactOut) - Simplifies feeCurrency assignment since it always matches unspecifiedIsToken0 Fixes Uniswap#1101
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Summary
This PR fixes a bug in the
afterSwaphook fee example where the fee amount was incorrectly calculated for exact output swaps.The issue: The documentation correctly states that the returned
int128is for the unspecified currency (output for exactIn, input for exactOut), but the code example always calculated the fee fromoutputAmount, which is wrong for exactOut swaps.The fix:
Changes
Fixes #1101