On Friday, 30 July 2021 09:20:45 BST John Covici wrote:
> On Thu, 29 Jul 2021 23:20:59 -0400,
> 
> thelma@sys-concept.com wrote:
> > On 7/29/21 9:10 PM, thelma@sys-concept.com wrote:
> > [snip]
> > 
> > > It seems to me "dev-lang/perl-5.34" was made stable and it is causing a
> > > problem.> 
> > I've tried to block perl-5.34 but I'm getting another conflict:
> > 
> > !!! Multiple package instances within a single package slot have been
> > pulled !!! into the dependency graph, resulting in a slot conflict:
> > 
> > dev-libs/icu:0
> > 
> >   (dev-libs/icu-69.1:0/69.1::gentoo, ebuild scheduled for merge)
> >   USE="-debug -doc -examples -static-libs" ABI_X86="(64) -32 (-x32)"
> >   pulled in by>   
> >     dev-libs/icu:0/69.1 required by
> >     (app-office/libreoffice-bin-7.1.3.2:0/0::gentoo, ebuild scheduled for
> >     merge) USE="java -gnome -kde" ABI_X86="(64)"
> >     PYTHON_SINGLE_TARGET="python3_9">     
> >                 ^^^^^^^
> 
> I would do two things --- put --verbose-conflicts  in your emerge
> command and then remove all the masked packages that you have done.
> Then you will get a better picture of what is really happening.  I
> would definitely update all your tool chains in this process, maybe
> seperately if you have not done it for a very long time.
> 
> I know its a mess with that icu business, but you maybe stuck -- it
> might be easier to do a re install.

First re-sync and then run:

emerge -uaNDv @system

This should bring your toolchain up to date.  Then carry on with @world.  
There were some perl updates recently and a perl-cleaner is probably necessary 
in the aftermath.