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Reverting on `approve()` if allowance is not 0 is not compliant with ERC-20 interface #6

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sohkai opened this issue Jun 3, 2020 · 0 comments

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sohkai commented Jun 3, 2020

See https://github.com/aragon/minime/blob/master/contracts/MiniMeToken.sol#L232-L236.

Some discussion on this was held in OpenZeppelin: github.com/OpenZeppelin/openzeppelin-contracts/issues/438, and is in the ERC20 spec:

NOTE: To prevent attack vectors like the one described here and discussed here, clients SHOULD make sure to create user interfaces in such a way that they set the allowance first to 0 before setting it to another value for the same spender. THOUGH The contract itself shouldn't enforce it, to allow backwards compatilibilty with contracts deployed before

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