to_matrices is called before inline_all_lcs

[weikengchen]

The current master branch may fail to index a circuit because the index function would call:

let matrices = cs.to_matrices().unwrap();

in make_matrices_square_for_indexer, before calling inline_all_lcs.

As a result, a developer would see "no symbolic LCs".

---

This problem is indeed fixed in the constraints PR #39 by removing a check in make_matrices_square_for_indexer.

See https://github.com/arkworks-rs/marlin/pull/39/files#diff-4a24591214fb91bafc31f147e9f82b39471e7a773de92a5a36f0776f434c6158R54

But I think we are not going to merge that PR soon, it may be worthwhile to fix this one sooner. (I will work to finish the constraints PR of poly-commit soon.)

[Pratyush]

Adding a comment from #42:

Because outlining changes the dimensions of the matrices, we should probably be making the matrices square after outlining, no?

[Pratyush]

Is this issue closeable @weikengchen ?