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

Calculating dependencies ... done!
Dependency resolution took 1.04 s (backtrack: 1/20).



[ebuild  N     ] dev-ml/yojson-2.2.2-r1:0/2.2.2::gentoo  USE="ocamlopt -examples -test" 58 KiB
[ebuild  N     ]  dev-ml/sedlex-3.7:0/3.7::gentoo  USE="ocamlopt -test" 141 KiB
[ebuild  N     ]   dev-ml/ppxlib-0.39.0:0/0.39.0::gentoo  USE="ocamlopt -test" 687 KiB

Total: 3 packages (3 new), Size of downloads: 884 KiB

 * Error: circular dependencies:

(dev-ml/ppxlib-0.39.0:0/0.39.0::gentoo, ebuild scheduled for merge) depends on
 (dev-ml/yojson-2.2.2-r1:0/2.2.2::gentoo, ebuild scheduled for merge) (buildtime_slot_op)
  (dev-ml/ppxlib-0.39.0:0/0.39.0::gentoo, ebuild scheduled for merge) (buildtime_slot_op)

 * Note that circular dependencies can often be avoided by temporarily
 * disabling USE flags that trigger optional dependencies.