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require not working in view/pure functions

See original GitHub issue

Many functions in openzepplin contracts are using require statement in view function but it doesn’t work as expected.

📝 Details require in view function does not actually perform any role for now. It is being used in many openzepplin contract. For example: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/ERC721.sol#L62 https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/ERC721.sol#L74 https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/token/ERC721/ERC721.sol#L106

It doesn’t stop execution even if require condition is false and return the output. In case address is return data type, it returns zero address and in case uint256 is return type, it returns 3963877391197344453575983046348115674221700746820753546331534351508065746944 whose hex value is 8C379A000000000000000000000000000000000000000000000000000000000 which is the function selector for function Error(string).

Also this works fine with remix-vm and truffle test vm but shows above behaviour with each Ethereum testnet.

I think we need to add a note to inform the users about it in function developer comments or do what is discussed.

Issue Analytics

State:
Created 4 years ago
Comments:7 (7 by maintainers)

Top GitHub Comments

2reactions

frangiocommented, Sep 9, 2019

Thanks for bringing this up @Aniket-Engg! It’s an interesting subtlety. Unfortunately since this affects basically everything, I’m not sure where we would place the notice in our documentation. I guess we can consider that this has been tackled by @abcoathup’s thorough forum post and close it.

2reactions

abcoathupcommented, Aug 21, 2019

Hi @Aniket-Engg

Thanks for raising this. I have created a topic in the forum and made it a wiki post (so that anyone can edit it): https://forum.openzeppelin.com/t/require-in-view-pure-functions-dont-revert-on-public-networks/1211