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

Calculating dependencies ...

!!! Problem resolving dependencies for =media-libs/libmetalink-0.1.3-r3
 done!
Dependency resolution took 0.83 s (backtrack: 0/20).


!!! The ebuild selected to satisfy "=media-libs/libmetalink-0.1.3-r3" has unmet requirements.
- media-libs/libmetalink-0.1.3-r3::gentoo USE="-expat -static-libs -test -xml"

  The following REQUIRED_USE flag constraints are unsatisfied:
    exactly-one-of ( expat xml )