Add reserved attribute

[shargon]

Close #1904

[AnnaShaleva]

@shargon, are we planning to include this PR into 3.6.0?

[shargon]

@shargon, are we planning to include this PR into 3.6.0?

I'm not in a hurry, except that @roman-khimov or @vncoelho want to

[roman-khimov]

Certainly not a blocker for 3.6, but it's good you've updated it anyway.

[roman-khimov]

Actually, the idea was to have a range of attributes (suppose you're creating an alternative to #1573 and defining 10 attributes instead of 3). And it's better be some upper range to reduce collisions with "regular" type.

[roman-khimov]

Like in #1904 (comment)

[vncoelho]

What do you mean by "Range of Attributes"?

In the way it is implemented we can setup a reserved byte that have ff possibilities as range for the dapp, right @shargon ?

[vncoelho]

Not in hurry, @shargon.

But this do not have any possible problem, does it have?
What if some transactions in the past used this attribute ID? Do we need to hard fork something?

[vncoelho]

            foreach (TransactionAttribute attribute in Attributes)
                if (!attribute.Verify(snapshot, this))
                    return VerifyResult.InvalidAttribute;

https://github.com/neo-project/neo/blob/535aa2057b6ddddb90b2009ef47f8ba16fd3d036/src/Neo/Network/P2P/Payloads/Transaction.cs#LL366C1-L368C58

[Jim8y]

Close as inactive