Eliminate duplicate math operations

[code423n4]

Handle

pauliax

Vulnerability details

Impact

Before:

  require(currentAllowance >= amount + burnt, "OVL:allowance<amount+burnt");
  unchecked { _approve(sender, msg.sender, currentAllowance - amount - burnt); }

After:

  uint totalAmount = amount + burnt;
  require(currentAllowance >= totalAmount, "OVL:allowance<amount+burnt");
  unchecked { _approve(sender, msg.sender, currentAllowance - totalAmount); }

This approach can be applied in several functions, e.g. transferFromBurn, _transferBurn.

[mesozoic-technology]

Super tiny savings here.