[slang][lang-compliance] Introduce nondegeneracy check

[likeamahoney]

Based on 16.12.22 SystemVerilog LRM section and partially (F.4.3/F.5.2/F.5.5).

Also Ben Cohen's paper about nondegeneracy understanding from here.

Complex sequences are not often used in industrial/open source designs, but I think these checks will help to verify restrictions from 16.12.22 in most cases.

I written about ~300 lines of sv tests but i need help with more complex test cases but if anyone could also come up with more complex tests to test heuristics, that would be nice.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 74.46043% with 71 lines in your changes are missing coverage. Please review.

Project coverage is 94.14%. Comparing base (b1354ad) to head (a4b2714).

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[MikePopoloski]

Thank you for tackling this; the sections of the LRM that address this are daunting which is why I had not implemented it yet. I'll have to review this quite closely.

One thing that can help inform additional tests is looking at the coverage report, which shows some big chunks that haven't been tested at all yet.

[likeamahoney]

Thank you for tackling this; the sections of the LRM that address this are daunting which is why I had not implemented it yet. I'll have to review this quite closely.

One thing that can help inform additional tests is looking at the coverage report, which shows some big chunks that haven't been tested at all yet.

At the moment I only added a few tests to increase the possible coverage but at all it still in progress

[likeamahoney]

Thank you for tackling this; the sections of the LRM that address this are daunting which is why I had not implemented it yet. I'll have to review this quite closely. One thing that can help inform additional tests is looking at the coverage report, which shows some big chunks that haven't been tested at all yet.

At the moment I only added a few tests to increase the possible coverage but at all it still in progress

And also add support for checking nondegenerancy for lhs of "followed-by property" properties (e.g. #-# and #=#)

[MikePopoloski]

Ok, I think this is good enough to land -- we can tweak or improve it later if needed.