TransferHelper Static Analysis Findings

THR-01S: Deprecated Approval Methodology

Type	Severity	Location
Standard Conformity		TransferHelper.sol:L34

Description:

The linked statement invokes the safeApprove function which has been officially deprecated by the OpenZeppelin standard.

Impact:

The safeApprove function indirectly validates that the approval that already exists for the target party has been previously set to zero if being set to a non-zero value. This can cause significant issues in the case of upgrade-able contracts or contracts whose allowance may not be utilized in full as subsequent safeApprove invocations will fail rendering it inoperable.

Example:

Copy
34IERC20(token).safeApprove(to, value);

Recommendation:

We advise the code to utilize a safeIncreaseAllowance and / or a safeDecreaseAllowance depending on the execution context and desired result.

Alleviation:

The deprecated safeApprove approval methodology has been replaced by two new safeIncreaseAllowance and safeDecreaseAllowance functions that behave in a standard way.