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

Calculating dependencies ... done!
Dependency resolution took 1.04 s (backtrack: 0/20).

[ebuild  N     ] dev-cpp/gflags-2.2.2-r1:0/2.2::gentoo  USE="-static-libs -test" 97 KiB
[ebuild  N     ] dev-cpp/glog-0.6.0-r1:0/1::gentoo  USE="libunwind -gflags -llvm-libunwind -test" 189 KiB
[ebuild  N     ] dev-libs/pfs-0.10.0::gentoo  USE="-test" 235 KiB
[ebuild  N     ] dev-cpp/nlohmann_json-3.12.0-r1::gentoo  USE="-test" 9452 KiB
[ebuild  N     ] dev-cpp/gtest-1.17.0:0/1.17.0::gentoo  USE="(-abseil) -doc -examples -test" 865 KiB
[ebuild  N     ] dev-libs/dynolog-0.3.2-r1::gentoo  USE="-debug -perf-events -test" 18262 KiB

Total: 6 packages (6 new), Size of downloads: 29098 KiB