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

Calculating dependencies ... done!
Dependency resolution took 1.00 s (backtrack: 0/20).

[ebuild  N     ] dev-libs/libdwarf-2.3.2:0/2::gentoo  USE="-dwarfexample -dwarfgen -test" 3593 KiB
[ebuild  N     ] dev-cpp/cpptrace-1.0.4-r1::gentoo  USE="-test -unwind" 483 KiB

Total: 2 packages (2 new), Size of downloads: 4076 KiB