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

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

[ebuild     UD ] dev-lang/swig-4.2.1::gentoo [4.3.1::gentoo] USE="pcre -ccache -doc -test" 8169 KiB

Total: 1 package (1 downgrade), Size of downloads: 8169 KiB