Use extcodehash instead of extcodesize

[abhi3700]

🧐 Motivation
This is for saving gas by 300 unit.

📝 Details
The extcodesize uses 300 gas more than extcodehash to determine whether or not an address is a contract. Hence, this is pertaining to that.

This line-27 refers to the isContract function in AddressUpgradeable.sol file. This function is supposed to modified to this:

function isContract(address account) public view returns (bool) {
    bytes32 hash;
    assembly {
        hash := extcodehash(account)
    }
    return (hash != 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470);
}

[Amxx]

Hello @abhi3700

I think this is a really interesting proposal. It should however be done on the @openzeppelin-contracts repository. Can you please open an issue there?

[frangio]

See OpenZeppelin/openzeppelin-contracts#1802 (comment). We used extcodehash in the past but went back to extcodesize as it was shown to be more efficient. If this is no longer the case please open another issue.