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

Calculating dependencies ... done!
Dependency resolution took 1.53 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

Total: 1 package (1 downgrade), Size of downloads: 6859 KiB