Re: [Monotone-devel] Re: using empty() instead of size()

[Ulf Ochsenfahrt]

Bruce Stephens wrote:
> "Derek Scherger" <address@hidden> writes:
>
> > Even if size does have to traverse a list to count the elements one would
> > expect that traversing an *empty* list should be reasonably quick.
>
> Sure, but presumably the extra cost is traversing a non-empty list to
> find that it's not empty.  One would hope that an inlined size()
> together with a good optimizing compiler might be able to avoid the
> cost, but perhaps that's not feasible.

If there is an invalid pointer in the non-empty list, the program can 
crash. If the compiler optimizes (i.e. removes) the list traversal, the 
program doesn't crash. Thus, the optimization would change the runtime 
behavior of the program.

Cheers,

-- Ulf