Return amount in cancel and withdraw functions

[smol-ninja]

While brainstorming https://github.com/sablier-labs/company-discussions/discussions/85, I came to realize that its super useful to return amounts in functions which transfer tokens:

• cancel
• cancelMultiple
• withdrawMax
• withdrawMaxAndTransfer

Currently, it requires making two calls such as refundableAmountOf followed by cancel.

cc @sablier-labs/solidity in case you have any objection.

[andreivladbrg]

Re the withdraw functions, we already have return values for the "Max" functions (which is what matters—this was also added after this finding). As for withdraw and withdrawMultiple, I don’t think it’s relevant, as we already have the amount parameters:

//                            ↓ integrators are already in control of the amount that is being withdrawn
lockup.withdraw(streamId, to, amount);

As for the cancel and cancelMultiple functions, I remember talking about this before, but I can’t find where exactly, so I’m not sure what arguments were raised back then. The question now is: what amount should be returned—the refunded amount to the sender or the recipient’s withdrawable amount? Should we return one, or both?

[smol-ninja]

Agree with your argument with withdraw and withdrawMultiple.

Re. cancel and cancelMultiple, I would suggest to return the amount transferred to the sender. Its the sender who is calling these functions and should be returned the amount transferred to him.

[PaulRBerg]

Agree with the plan.