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

Calculating dependencies ... done!
Dependency resolution took 1.51 s (backtrack: 0/20).

[ebuild     UD ] sys-libs/libunwind-1.8.2-r1:0/8::gentoo [1.8.3:0/8::gentoo] USE="zlib -debug -debug-frame -doc -libatomic -lzma -static-libs -test" 986 KiB

Total: 1 package (1 downgrade), Size of downloads: 986 KiB