Auth Code Style Findings

AUT-01C: Counter-Intuitive Optimization

Type	Severity	Location
Gas Optimization		Auth.sol:L32

Description:

The linked local variable is a remnant of the original solmate codebase where the authority variable is not immutable.

Example:

Copy
31function isAuthorized(address user, bytes4 functionSig) internal view virtual returns (bool) {
32    Authority auth = authority; // Memoizing authority saves us a warm SLOAD, around 100 gas.
33
34    // Checking if the caller is the owner only after calling the authority saves gas in most cases, but be
35    // aware that this makes protected functions uncallable even to the owner if the authority is out of order.
36    return (address(auth) != address(0) && auth.canCall(user, address(this), functionSig)) || user == owner;
37}

Recommendation:

We advise the local auth variable to be removed as it increases the gas cost instead of reducing it as no SLOAD is performed for authority.

Alleviation:

The Morpho team heeded our recommendation and revamped the original Solmate codebase to instead reflect access control calls to itself internally, significantly optimizing the gas cost of the contract.