Circuit::configure() forces you to know the circuit configuration at compile time

[georgwiese]

The Circuit trait requires me to implement the configure() function, defined as:

    /// The circuit is given an opportunity to describe the exact gate
    /// arrangement, column arrangement, etc.
    fn configure(meta: &mut ConstraintSystem<F>) -> Self::Config;

Because (unlike Circuit::synthesize()) I don't have access to &self here, I must know the configuration at compile time.

What's the reason for that? Is there a way around it?

In my case, I'm writing a tool that proves the inference of an ML model. The exact circuit depends on the model, which is dynamically loaded from a file. I understand the model needs to be available at key generation time, but why must I compile it into the program?

[georgwiese]

So it turns out that this is fixed in the PSE fork by privacy-scaling-explorations#168: One can activate the circuit-params feature, which adds two functions to the Circuit trait:

    fn params(&self) -> Self::Params;

    fn configure_with_params(
        meta: &mut ConstraintSystem<F>,
        _params: Self::Params,
    ) -> Self::Config:

That way, you can access self indirectly because the prover will do:

let config = ConcreteCircuit::configure_with_params(&mut cs, circuit.params());

This solves the problem for me! However, I'll leave the issue open for now, as this repo doesn't seem to have an equivalent solution.