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

Calculating dependencies ... done!
Dependency resolution took 1.55 s (backtrack: 0/20).

[ebuild     UD ] dev-lang/tcl-8.6.16:0/8.6::gentoo [8.6.17:0/8.6::gentoo] USE="threads -debug" 6859 KiB
[ebuild  N     ] dev-lang/tk-8.6.16:0/8.6::gentoo  USE="threads truetype (-aqua) -debug -test -xscreensaver" 4485 KiB

Total: 2 packages (1 downgrade, 1 new), Size of downloads: 11343 KiB