Encapsulate Unit return check

[joss-aztec]

Problem

Acir gen contains a brittle check for inferring whether or not a function returns Unit, which could be overlooked if the underlying representation changed. This check should be encapsulated.

Happy Case

Kev's suggestion

Alternatives Considered

No response

Additional Context

No response

Would you like to submit a PR for this Issue?

No

Support Needs

No response

[jfecher]

We should remove this check entirely and instead remove all unit values from the ssa form since they will never be used in operations. This would be similar to rust's elision of zero-sized types.

[joss-aztec]

So we'd instead infer the program returns no value by checking return_values.len() == 0?

[jfecher]

Right, and I think that'd be more straightforward as well.

[jfecher]

Looking at the check in question though, we wouldn't need it at all since the loop afterward would just loop 0 times

[joss-aztec]

@jfecher, do you still hope to remove unit values?

[joss-aztec]

Closing, as this has been addressed by #1646