Re: [gentoo-alt] Re: [PREFIX] Bootstrap stable?

[Fabian Groffen]

Hi Francois,

On 04-04-2019 07:23:50 +0000, Francois Bissey wrote:
> > On 4/04/2019, at 19:49, Fabian Groffen <grobian@g.o> wrote:
[snip]
> > On 04-04-2019 01:51:58 +0000, Francois Bissey wrote:
[snip]
> >> Basically if you want to reproduce some the scenarios managed by spack you
> >> need multiple prefix.
> >
> > So what scenarios exactly are these?
>
> It can be several versions of the same software as stated earlier. Either executable
> or libraries.
> For example while gromacs 5.x was stable a user wanted me to resurrect a copy of gromacs
> 3 something because it was the last version with a particular potential in the feature
> set and that’s what they wanted to use.
> You can have the same software compiled with different compilers. Which can be various
> version of gcc/intel compilers or other proprietary compiler (PGI comes to mind as well
> as cray which has its own toolchain). Because of potential incompatibilities in the
> Fortran binary interface you will have a tree by fortran compiler vendor and sometimes
> different version of the same compiler (gcc 4 to 6, gcc 7 and gcc 8 all have a different
> runtime want to troll bugzilla to see how many problems that created to users?).
> People will want a particular compiler because the software they use compiled with
> another compiler won’t pass the test suite or crash in their particular extreme
> scenario. And another group using the same software will want a different compiler for the
> same reason.

I see.  The tendency of Gentoo (or: some developers) has been to reduce
slots and concurrent versions.  GCC once had USE=multislot for instance,
Perl used to be slotted.  but I see how there is a wide range of
packages that never were slotted in Gentoo, and/or never will be.
I know there are projects that install "pillars" or something that
truely allow multiple concurrent versions to be installed, because they
use completely different target trees.  Prefix wasn't designed to be
like that, this would require a different approach from Portage itself.

I could see something like stacked prefixes to suit some of the above
use-cases, combined with binpkg support to quickly launch various
different incarnations of combinations of tools.  Nevertheless, there
will be problems.  And Prefix is never going to solve them all :)

Thanks for your explanation, I'm sure there must be some "pain" in even
having to describe the situation ...

Fabian

[snip]

-- 
Fabian Groffen
Gentoo on a different level