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

Calculating dependencies ... done!
Dependency resolution took 1.03 s (backtrack: 0/20).

[ebuild  N     ] dev-libs/pcl-1.12-r2:0/1::gentoo  376 KiB
[ebuild  N     ] dev-libs/libatomic_ops-7.10.0::gentoo  531 KiB
[ebuild  N     ] dev-libs/boehm-gc-8.2.12::gentoo  USE="large threads -cxx -static-libs" 1204 KiB
[ebuild  N     ] dev-lang/crystal-1.21.0::gentoo  USE="-debug -doc -llvm-libunwind" LLVM_SLOT="22 -20 -21" 60682 KiB

Total: 4 packages (4 new), Size of downloads: 62791 KiB