Re: [gentoo-user] Building packages in different prefix without rebuilding system packages

["François-Xavier Carton" <fx.carton@yahoo.fr>]

On Thu, May 14, 2020 at 09:26:10AM -0400, Michael Orlitzky wrote:
> On 5/14/20 7:55 AM, Neil Bothwick wrote:
> > On Thu, 14 May 2020 18:17:06 +0800, Pengcheng Xu wrote:
> > 
> >> That seems interesting.  Do we need to include Portage install prefix
> >> (/var/tmp/portage/category/package/..., the image path prefix before
> >> actually merging with /)?
> >>
> >> Regards,
> > 
> > No, just the --prefix=/home/blah/ that you want added to the ./configure
> > invocation.
> > 
> 
> This is a good way to install packages that you've built by hand into
> (say) your home directory, but it will cause problems if you try to
> trick portage into doing it. The big problem is that no other packages
> are going to know where to find the thing you just installed. Everything
> else in the Gentoo repository is designed to use standard values of
> PATH, LD_LIBRARY_PATH, the compiler's include dir, PKG_CONFIG_PATH, etc.
> If you take one program and put it somewhere non-standard, then every
> package depending on it is going to break.
> 
> If you install an *additional* copy (built by hand) in your home
> directory, that's fine -- the system copy will still be in the right
> place -- you just don't want to hide the system copy where nobody can
> find it.
> 

In my case, this wouldn't be a problem: I don't want the packages to be
accessed by anyone, just one user. I can set PATH, LD_LIBRARY_PATH,
PKG_CONFIG_PATH and MANPATH for that user. I already do that for things
I build manually anyway.

EXTRA_ECONF is nice, I didn't know about it. It looks like MYCMAKEARGS
can be used for cmake ebuilds. For other build systems, it might be
necessary to edit the ebuild, or set different variables.

I still kinda think that being able to install with a prefix (like
EPREFIX) but using the base system would be a nice feature. As discussed
previously, there would be the problem of updates; but it isn't very
different from installing software manually. If I clone something and
build it locally, a world update might break break it, and portage
cannot rebuild it automatically since it's not aware of it. This is why
I think it would be nice if portage supported it; that way, after an
update of the base system, updating the prefix system would solve the
problems. It's probably difficult to implement that in portage, though.