Tautological Compare Remediation

Overview

Related Detector: Tautological Compare

A condition whose result is fixed by type — uint >= 0 (always true), uint < 0 (always false) — provides no protection. It usually means the author intended a meaningful bound (> 0, >= minAmount) but wrote something the compiler can constant-fold. The remediation is to replace the tautology with the check that was actually intended.

Recommended Fix

Before (Vulnerable)

function deposit(uint256 amount) external {
    require(amount >= 0, "Invalid amount");   // always true — zero-value deposits slip through
    _credit(msg.sender, amount);
}

After (Fixed — the intended bound)

function deposit(uint256 amount) external {
    require(amount > 0, "Amount must be positive");   // real check
    _credit(msg.sender, amount);
}

Trace what the guard was protecting: a minimum size, a non-zero requirement, or a real upper bound — then encode that.

Common Mistakes

“Fixing” amount >= 0 to amount != 0 when the intent was actually a minimum threshold (>= minAmount).
Leaving a signed/unsigned confusion in place, where the impossible branch hides a real edge case.
Removing the check entirely instead of replacing it, dropping validation the function needs.