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

Calculating dependencies ... done!
Dependency resolution took 1.06 s (backtrack: 0/20).

[ebuild  N     ] dev-lang/tk-8.6.17:0/8.6::gentoo  USE="threads truetype (-aqua) -debug -test -xscreensaver" 4486 KiB
[ebuild  N     ] app-shells/tcsh-6.24.16::gentoo  USE="nls -man" 939 KiB
[ebuild  N     ] sci-electronics/irsim-9.7.93-r1::gentoo  464 KiB

Total: 3 packages (3 new), Size of downloads: 5888 KiB