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,
-- 
Pengcheng Xu
https://jsteward.moe

> -----Original Message-----
> From: Neil Bothwick <neil@digimed.co.uk>
> Sent: Thursday, May 14, 2020 6:07 PM
> To: gentoo-user@lists.gentoo.org
> Subject: Re: [gentoo-user] Building packages in different prefix without
> rebuilding system packages
> 
> On Thu, 14 May 2020 16:46:58 +0800, Pengcheng Xu wrote:
> 
> > What you're trying to achieve sounded a lot like `./configure
> > --prefix=...` to me.  If you're just dealing a small amount of things,
> > I would suggest modifying the ebuild (in a local overlay) and changes
> > where the program installs to.
> 
> You may be able to avoid modifying ebuilds by setting the --prefix option in
> $EXTRA_ECONF.
> 
> 
> --
> Neil Bothwick
> 
> Top Oxymorons Number 8: Tight slacks