fix!: correct the compile_circuit

[guorong009]

Description

Correct the logic of converting selectors to fixed columns in compile_circuit

Related issues

• None

Changes

• update compile_circuit
  add the logic of considering the selectors_poly when computing fixed columns
• add a new ci check for running the examples
  • create a new sh script to test the successful run of examples
  • add ci check in github actions

Context

If you try to run the shuffle example in current main branch, you can find that it is failing here.

cargo run --package halo2_proofs --example shuffle 

The reason is that there is tiny error in the implementation converting selectors to fixed column, in compile_circuit. This PR resolves this issue.

[ed255]

There's a detail here that I don't understand. With this change the cs we get here has selector columns (they have not yet been converted to fixed columns).

Then afterwards we convert the ConstraintSystem into ConstraintSystemMid. In that conversion we're converting Expression into ExpressionMid, and if the Expression has a selector it will panic:

halo2/halo2_frontend/src/plonk/circuit/expression.rs

Line 471 in 9eedeb5

Expression::Selector(_) => unreachable!(),

So I think that calling vk_read or pk_read for a circuit that uses Selectors will panic.

[guorong009]

Hmm, I don't think so.
The pk_read & vk_read are utilities to read the keys that were already compiled & stored somewhere.
In other word, the keys include the info of fixed columns converted from Selectors, not Selectors.

[ed255]

If you try to run the shuffle example in current main branch, you can find that it is failing here.

cargo run --package halo2_proofs --example shuffle 

I think this is showing a big problem we have, we don't have enough unit tests, and the real tests that we have are examples but they are not run via github actions. I think we should run the examples as check via github actions for every PR.

[guorong009]

If you try to run the shuffle example in current main branch, you can find that it is failing here.

cargo run --package halo2_proofs --example shuffle 

I think this is showing a big problem we have, we don't have enough unit tests, and the real tests that we have are examples but they are not run via github actions. I think we should run the examples as check via github actions for every PR.

Yes, I agree. @ed255
Here, I add the CI to check examples running. 5627fce 41e4da2

[guorong009]

Close this PR in favor of #322 .