Bug Report

Cairo version: 2.3.0

Current behavior:

We need to be able to handle recursive structures in Kakarot for the RLP decoding. The tests were running correctly in version 2.3.0-rc0 but are failing in 2.3.0 with this error :

thread 'main' panicked at /cargo/registry/src/index.crates.io-6f17d22bba15001f/salsa-0.16.1/src/lib.rs:490:48:
Internal error, cycle detected:

DatabaseKeyIndex { group_index: 2, query_index: 29, key_index: 759 }
DatabaseKeyIndex { group_index: 2, query_index: 29, key_index: 760 }

note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Error: 'scarb metadata' exited with error

If I modify the struct and the tests so that they don’t use struct recursion, the tests will run.

Expected behavior:

To be able to use struct recursion in 2.3.0 as well.

Steps to reproduce:

Ironically, I couldn’t reproduce the bug in a MRE so I might only be able to link you the related PR : https://github.com/kkrt-labs/kakarot-ssj/pull/457#issuecomment-1780949444

Once pulled, you should be able to run scarb test -f test_rlp. Once using cairo 2.3.0-rc0 and assert that the tests run. And once using cairo 2.3.0 and assert that the tests panic with the error mentionned above. (Do not forget to modify the Scarb.toml as well)

Here is the related struct found in rlp.cairo:

#[derive(Drop, Copy, PartialEq)]
enum RLPItem {
    String: Span<u8>,
    List: Span<RLPItem>
}

Any tests calling the decode() function will trigger the error.

Other information:

I tried to reproduce the bug in a brand new scarb project but it is running smoothly. I will keep updated if I manage to reproduce the bug in a smaller setup. This is confusing.