Well, you probably meant assert(A || !A), but even so that will of course never be an issue if A is a value, it becomes only a problem if A is replaced by somet

Well, you probably meant assert(A || !A), but even so that will of course never be an issue if A is a value, it becomes only a problem if A is replaced by something like a() (which I assume to be a pure function for the purpose of this comment). Of course a() || !a() is never going to be false either, so assert(a() || !a()) will never abort your program, but that doesn't mean a() || !a() will ever be true (if a() never finishes calculating then neither will a() || !a()).