Re: [gentoo-dev] rfc: glibc versions prior to 2.19-r1

[Andrew Savchenko]

On Mon, 22 Dec 2014 22:22:41 +0100 Andreas K. Huettel wrote:
> Am Montag, 22. Dezember 2014, 17:20:31 schrieb Andrew Savchenko:
> > On Mon, 22 Dec 2014 17:11:01 +0100 Andreas K. Huettel wrote:
> > [...]
> >
> > > (On a related note, do we really need gcc 2.95.3-r10, 3.3.6-r1, 3.4.6-r2,
> > > 4.0.4, 4.1.2, 4.2.4-r1, 4.3.6-r1, 4.4.7, 4.5.1-r1, 4.5.2, 4.5.3-r2,
> > > 4.5.4, 4.6.0, 4.6.1-r1, 4.6.2, 4.6.3, 4.6.4, 4.7.0, 4.7.1, 4.7.2-r1,
> > > 4.7.3-r1, 4.7.4, 4.8.0, 4.8.1-r1, 4.8.2, 4.8.3, 4.9.0, 4.9.1, and (deep
> > > breath) 4.9.2?
> >
> > Yes, we do. There is a lot of software out there which needs
> > specific gcc version. E.g. I have fortran code which depends
> > gcc:3.4. Other example are cuda implementations which usually lag
> > behind mainstream gcc by one middle version.
>
> Which gives us 3.4, 4.6, 4.7, 4.8, 4.9 at most.

That was just two examples from my experience. Other users may
have different demands. That's why I'm not sure it is safe to
remove 2.95. Also people may need older versions for testing (e.g.
to check for possible regressions).

As far as I understand right now older gcc versions are not a large
maintenance hassle, so to be on a safe side we should keep the
latest version on each branch. That is exactly what is done right
now: prior to (4.5) we have only latest ebuild per branch.

> > And please don't say "just fix it",
>
> I'm not saying "just fix it", I'm saying "... and of course you will happily
> join toolchain team and/or maintain the single gcc version that you need, at
> your own pace".

Frankly I had thoughts about joining toolchain, but probably I'm
too green as a Gentoo dev to do this right now.

> > some of such software is
> > binary, some other is too large to be updated regularly.
>
> Please give REASONS why things should remain maintained. So far (except for
> the gcc-3/hardened explanations, and for gcc-3 doing more fortran than
> gcc-4(??)) this is mostly mumbo-jumbo about "someone might need it",
> proprietary binary blobs (should we even care? if yes, why?) and similar.
>
> I'm VERY happy to hear arguments. Especially if they come with good practical
> and detailed examples that we all can understand. I guess we're all curious to
> learn about more Gentoo use cases.

I can't justify for you each gcc version in the list, but I already
described use cases I encountered. The main point is that most
users don't read this list and it is highly likely that people need
another gcc versions for similar reasons but for a different
software.

As far as I understand from this discussion, a main issue is that
proposed changes in toolchain.eclass will broke old ebuilds.
Solution looks very simple to me: just use toolchain-v2.eclass for
new stuff.

Best regards,
Andrew Savchenko