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

Calculating dependencies ... done!
Dependency resolution took 1.41 s (backtrack: 0/20).


The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by dev-python/matplotlib-3.11.2::gentoo[-test]
# required by sci-chemistry/chemex-2026.9.2::gentoo[-test,python_single_target_python3_14]
# required by =sci-chemistry/chemex-2026.9.2 (argument)
>=dev-python/pillow-13.0.0 webp

!!! The ebuild selected to satisfy ">=sci-libs/hdf5-1.10.4:=[hl(+)]" has unmet requirements.
- sci-libs/hdf5-2.2.0::gentoo USE="hl threads zlib -cxx -debug -fortran -mpi -szip -test -unsupported"

  The following REQUIRED_USE flag constraints are unsatisfied:
    !unsupported? ( threads? ( !hl ) )

  The above constraints are a subset of the following complete expression:
    !unsupported? ( at-most-one-of ( cxx mpi ) threads? ( !cxx !mpi !fortran !hl ) )

(dependency required by "dev-python/h5py-3.16.0::gentoo[-test]" [ebuild])
(dependency required by "dev-python/emcee-3.1.6::gentoo[-test]" [ebuild])
(dependency required by "sci-chemistry/chemex-2026.9.2::gentoo[-test,python_single_target_python3_14]" [ebuild])
(dependency required by "=sci-chemistry/chemex-2026.9.2" [argument])