Hidden re-ordering of packages passed to opam show

[craigfe]

When invoking opam show with multiple packages, the results are reported in alphabetical order of package name. This is fine (if a bit odd) when all of the metadata is displayed, but is a bit pernicious when used in combination with the --field option:

ᐅ opam show --field=version -- irmin ocamlformat alcotest
1.1.0
2.1.0
0.14.1

(Here the versions are in the order alcotest, irmin, ocamlformat, but this is non-obvious.)

I would expect the result order to be the same as the order of options passed to opam show. Failing that, the manpage for opam show should probably indicate that results given out-of-order.

[rjbou]

Internally, opam reorder, but I don't know if it the intended behavior since the beginning or a side-effect.
@samoht @dbuenzli how do you handle that in your scripts?

[samoht]

I don't think any of my script is relying on that order.

[avsm]

I've typically passed --field=name,version and parsed the output. I agree that preserving the input order would minimise surprise.