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

Calculating dependencies ... done!
Dependency resolution took 0.97 s (backtrack: 0/20).

[ebuild  N     ] dev-lang/ocaml-5.5.1:0/5.5.1::gentoo  USE="ocamlopt -emacs -flambda -latex -test -xemacs" 6457 KiB
[ebuild  N     ] dev-ml/findlib-1.9.6-r1::gentoo  USE="ocamlopt -doc -tk" 265 KiB
[blocks B      ] dev-ml/findlib:0/0 ("dev-ml/findlib:0/0" is soft blocking dev-lang/ocaml-5.5.1)

Total: 2 packages (2 new), Size of downloads: 6722 KiB
Conflict: 1 block (1 unsatisfied)

 * Error: The above package list contains packages which cannot be
 * installed at the same time on the same system.

  (dev-ml/findlib-1.9.6-r1:0/0::gentoo, ebuild scheduled for merge) pulled in by
    =dev-ml/findlib-1.9.6-r1


For more information about Blocked Packages, please refer to the following
section of the Gentoo Linux x86 Handbook (architecture is irrelevant):

https://wiki.gentoo.org/wiki/Handbook:X86/Working/Portage#Blocked_packages