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-devel/m4-1.4.20::gentoo [1.4.21::gentoo] USE="nls -examples -verify-sig" 1997 KiB

Total: 1 package (1 downgrade), Size of downloads: 1997 KiB