Re: [PATCH 1/2] diff: Fix modified lines stats with --stat and --numstat

> Thomas Guyot <tguyot@gmail.com> writes:
> 
> It is not "both ways", I think.  The idea is that when this variable
> is true, we know with certainty that these two are the same, but
> even when the variable is false, they still can be the same.  So
> true does mean there will not be diff.  False indeed is fuzzy.

> And as long as one side gives a 100% correct answer cheaply, we can
> use it as an optimization (and 'true' being that side in this case).
> 
> I have a mild suspicion that the name same_anything conveys a wrong
> impression, no matter what word you use for <anything>.  It does not
> capture that we are saying the "true" side has no false positive.
> 
> And that is why I alluded to "may_differ" earlier (with opposite
> polarity).  The flow would become:
> 
>     may_differ = !one->oid_valid || !two->oid_valid || !oideq(...);
> 
>     if (binary) {
>         if (!may_differ) {
>             added = deleted = 0;
>             ...
>         } else {
>             ... count added and deleted ...
>         }
>     } else if (rewrite) {
> 	...
>     } else if (may_differ) {
> 	... use xdl ...
>     }
> 
> and it would become quite straight-forward to follow.  When there is
> no chance that they may be different, we short-cut and otherwise we
> compute without cheating.  Only when they can be different, we do
> the expensive xdl thing.