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

Calculating dependencies ... done!
Dependency resolution took 0.99 s (backtrack: 0/20).

[ebuild  N     ] media-libs/flac-1.5.0:0/11-14::gentoo  USE="cxx -debug -ogg -static-libs" CPU_FLAGS_X86="avx avx2" 1054 KiB
[ebuild  N     ] dev-perl/Audio-FLAC-Header-2.400.0-r5::gentoo  USE="-test" PERL_FEATURES="ithreads (-debug) -quadmath" 119 KiB

Total: 2 packages (2 new), Size of downloads: 1172 KiB