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

Calculating dependencies ... done!
Dependency resolution took 1.52 s (backtrack: 0/20).

[ebuild     UD ] sys-devel/m4-1.4.19-r2::gentoo [1.4.21::gentoo] USE="nls -examples -verify-sig" 1623 KiB

Total: 1 package (1 downgrade), Size of downloads: 1623 KiB