Emit Approval events from burnFrom and transferFrom (Closes #74)

[truls]

No description provided.

[peteremiljensen]

You cannot tell from an approve event whether it's decreasing or increasing allowance? In other words, it is the same event whether you perform transferFrom or approves a number of tokens?

[truls]

You cannot tell from an approve event whether it's decreasing or increasing allowance? In other words, it is the same event whether you perform transferFrom or approves a number of tokens?

It is implemented according to OpenZeppelin/openzeppelin-contracts#707 which is referenced by the audit report. I'm not sure if ERC20 defines which events should be emitted and when.

[peteremiljensen]

But it looks like you are emitting an event with the transfer/burning value change instead of the new allowance value. You have to emit the new allowance value if you want it to match OpenZeppelin/openzeppelin-contracts#707

So, instead of

emit Approval(from, originSender, value);

you need

emit Approval(from, originSender, _externalERC20Storage.allowed(from, originSender));