[WIP] Fix PIL optimizer

[georgwiese]

Fixes #2051

[chriseth]

So you are saying that this code snippet x[0] is not turned into an IndexAccess(Reference("x"), 0) but instead into a Reference("x[0]")?

[georgwiese]

I'm not done with the test. Indeed, this seems to work in main, but something like this seems to be happening in the file referenced in #2051.

[georgwiese]

This is a small test to reproduce the issue: #2055

[georgwiese]

OK, I based this PR against #2055. Sounds like the way I fixed the issue is wrong though, the core issue is that there is a Reference("x[0]") in the first place?

This is how this prover function is represented:

{
    let intermediate = N::x[0] + 1_expr;
    query |i| {
        let _: expr = intermediate;
    }
}

Do you know how to fix it though? 😬

[georgwiese]

Superseded by #2056