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

Calculating dependencies ... done!
Dependency resolution took 0.98 s (backtrack: 0/20).

[ebuild  N     ] sci-libs/sundials-5.8.0:0/5::gentoo  USE="int64 openmp static-libs threads -doc -examples -fortran -hypre -lapack -mpi -sparse -superlumt" 23451 KiB

Total: 1 package (1 new), Size of downloads: 23451 KiB