[Toybox] sort -V

[Rob Landley]

On 12/19/18 1:41 PM, enh via Toybox wrote:
> it turns out that we have a few users of `sort -V`. i'd always assumed
> this meant "use the GNU strverscmp(3) function as your comparator" but
> no, it's slightly different...
> 
> https://www.gnu.org/software/coreutils/manual/html_node/Details-about-version-sort.html

That's really unpleasant.

> the first github match for that function says this:
> 
>   This implements the algorithm for comparison of version strings
>   specified by Debian and now widely adopted. The detailed
>   specification can be found in the Debian Policy Manual in the
>   section on the 'Version' control field. This version of the code
>   implements that from s5.6.12 of Debian Policy v3.8.0.1
>   http://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version

That's outright insane.

> at which point i _wish_ it was just the stupid strverscmp...

While I have some experience in this area:

https://github.com/landley/aboriginal/blob/master/sources/functions.sh#L248

It's not a happy thing.

What is the _context_ of the users of sort -V? If I do try to implement
something, what does success look like here? (Do we have a sort.test patch we
can start with?)

Rob

P.S. Still trying to finish grep --color, probably not getting to this today...