why not use tx.origin == msg.sender to judge the caller is a contract address or EOA?

[flyq]

https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/AddressUtils.sol

[nventuro]

First of all, isContract checks the code size for any address, not just the caller.

With that out of the way, there are multiple reasons why tx.origin is usually a bad idea, at least security-wise: see here an issue where removing it from Solidity was proposed, and here a suggestion from Vitalik to 'not assume that tx.origin will continue to be usable or meaningful'.

[flyq]

thx