These are the packages that would be merged, in order:

Calculating dependencies ...

!!! Problem resolving dependencies for =app-containers/docker-credential-helpers-0.9.9
 done!
Dependency resolution took 0.84 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "=app-containers/docker-credential-helpers-0.9.9" has unmet requirements.
- app-containers/docker-credential-helpers-0.9.9::gentoo USE="-keyring -pass"

  The following REQUIRED_USE flag constraints are unsatisfied:
    any-of ( keyring pass )