Lazily add clauses #61
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Slept on the problem. No. |
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I discovered a very sneaky (not really...) bug where incrementally added clauses can have the first two literals eliminated in such a way, that when the solver state is restored through reconstruction stack, they are assigned to false at level 0, making watch invariants invalid. Apparently, none of the incremental tests caught it.
The easiest solution I came up with is to always restore the solver first, and add clauses after. Perhaps not the cleanest solution, but we had something similar with having to memorize newly added clauses anyway. Why not go all in on the idea of adding clauses when needed?
I am sure there is another approach which adds clauses eagerly, but laziness is the simplest solution I came up with.