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

Calculating dependencies ... done!
Dependency resolution took 1.61 s (backtrack: 0/20).

[ebuild  N     ] dev-libs/libpcre-8.45-r4:3::gentoo  USE="bzip2 cxx jit pcre16 readline (unicode) zlib -libedit -pcre32 -static-libs -valgrind" 1542 KiB
[ebuild     UD ] app-shells/zsh-5.9-r7::gentoo [5.9.0.3-r2::gentoo] USE="gdbm pcre -caps -debug -doc -examples -maildir -static -valgrind" 3255 KiB

Total: 2 packages (1 downgrade, 1 new), Size of downloads: 4797 KiB