Usage of RLP builtin

[janezpodhostnik]

Current Behavior

When trying to use the RLP builtin functions I got really confused.

This does not work:

import RLP
//....
RLP.decodeString("...".utf8)
//....

This also does not work:

// import RLP
//....
decodeString("...".utf8)
//....

But (confusingly) this works:

//import RLP
//....
RLP.decodeString("...".utf8)
//....

Expected Behavior

This is a bit confusing, and is not obvious from the docs: https://cadence-lang.org/docs/1.0/language/built-in-functions#rlp

Maybe add an example to the docs, or even allow the import RLP even if it is not doing anything.

IMO, the best solution might actually be so that you have to import RLP...

Steps To Reproduce

I ran this in a go test env:

import RLP

transaction(){
    prepare(signer: auth(Storage, Contracts, Keys, Inbox, Capabilities) &Account) {
        var f: fun(): Void = fun(){}
        f = fun() {
            var i = 0
            while i < 110 {
                i = i + 1
                RLP.decodeString("xxxxxxxxxxxxxxxxxxxxxx".utf8)
            }
        }
        f()
    }
    execute {
        var f: fun(): Void = fun(){}
    }
}

Environment

- Cadence version: 1.0
- Network: any

[turbolent]

We should allow the import and not report an error.

This also applies to other contracts that are part of the standard library, e.g. BLS.