Member predicate UselessNullCoalescingExpression::StructuralComparisonConfig::candidate

Holds if elements x and y are candidates for testing structural equality.

Subclasses are expected to override this predicate to identify the top-level elements which they want to compare. Care should be taken to avoid identifying too many pairs of elements, as in general there are very many structurally equal subtrees in a program, and in order to keep the computation feasible we must focus attention.

Note that this relation is not expected to be symmetric – it’s fine to include a pair (x, y) but not (y, x). In fact, not including the symmetrically implied fact will save half the computation time on the structural comparison.

predicate candidate(Element x, Element y)