Member predicate C11GenericExpr::getAssociationExpr
Gets the expression of the nth element in the association list of
the generic selection.
For example, for
_Generic(e, int: "a", default: "b")
the expression for 0th element is "a", and the expression for the
1st element is "b". For the selected expression, this predicate
will yield a ReuseExpr, such that
this.getAssociationExpr(n).(ReuseExpr).getReusedExpr() = this.getExpr()