Bug#1110359: Bug#1110466: unblock: lapack/3.12.1-5

[Simon McVittie]

On Tue, 05 Aug 2025 at 20:25:29 -0400, M. Zhou wrote:
> Package: libatlas3-base
...
>+Depends: libblas3 (= ${binary:Version}), ${misc:Depends}
...
> Description: transitional package

Should this be (>= ${binary:Version}) instead of (=)?

In other packages that migrated to another name via a transitional 
package (gdk-pixbuf, pango1.0) we've seen that sometimes users of stable 
releases have to keep the transitional package installed for a long 
time, even after it has been eliminated from Debian (hopefully during 
forky in this case), because third-party packages outside Debian still 
have a dependency on the old name.

After upgrading the transitional libatlas3-base to its Debian 13 version 
(for simplicity let's pretend that it's version 13) there are three 
possible scenarios:

1. libatlas3-base (= 13), libblas3 (= 13): good.
    This is the only one allowed by the proposed dependency.

2. libatlas3-base (= 13), libblas3 (<< 13):
    bad, for the reasons Helmut gave on #1110466

3. libatlas3-base (= 13), libblas3 (>> 13):
    should be fine, we can assume that libblas3 (>> 13) is
    "better than" libblas3 (= 13)

So I think the best-practice for empty transitional packages is that 
they should retain their previous Architecture and Multi-Arch, and have:

     Depends: the-new-package (>= some suitable version)

Thanks,
     smcv