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

Calculating dependencies ... done!
Dependency resolution took 1.81 s (backtrack: 6/20).

[ebuild  N     ] app-text/dos2unix-7.5.7::gentoo  USE="nls -debug -test -verify-sig" 977 KiB
[ebuild  N     ] dev-lang/ghc-9.0.2-r4:0/9.0.2::gentoo  USE="gmp (-big-endian) -binary -doc -elfutils -ghcbootstrap -ghcmakebinary (-llvm) -numa -profile -test -unregisterised" 147774 KiB
[ebuild  N     ] app-admin/haskell-updater-1.5.0.0::gentoo  45 KiB
[ebuild  N     ] dev-haskell/parsec-3.1.14.0-r2:0/3.1.14.0::gentoo  USE="-doc -hscolour -profile" 40 KiB
[ebuild  N     ] dev-haskell/text-1.2.5.0-r1:0/1.2.5.0::gentoo  USE="-doc -hscolour -profile" 153 KiB
[ebuild  N     ] dev-haskell/fail-4.9.0.0:0/4.9.0.0::gentoo  USE="-profile" 3 KiB
[ebuild  N     ] dev-haskell/cabal-syntax-3.10.3.0:0/3.10.3.0::gentoo  USE="-doc -hscolour -profile" 228 KiB
[ebuild  N     ] dev-haskell/cabal-3.10.3.0:0/3.10.3.0::gentoo  USE="-doc -hscolour -profile" 389 KiB
[ebuild  N     ] dev-haskell/bytestring-builder-0.10.8.2.0-r1:0/0.10.8.2.0::gentoo  USE="-doc -hscolour -profile" 47 KiB
[ebuild  N     ] dev-haskell/cereal-0.5.8.1:0/0.5.8.1::gentoo  USE="-doc -hscolour -profile -test" 20 KiB

Total: 10 packages (10 new), Size of downloads: 149671 KiB

WARNING: One or more updates/rebuilds have been skipped due to a dependency conflict:

dev-lang/ghc:0

  (dev-lang/ghc-9.8.4-r1:0/9.8.4::gentoo, ebuild scheduled for merge) USE="gmp (-big-endian) -doc -elfutils -ghcbootstrap -ghcmakebinary -llvm -numa -profile -test -unregisterised -verify-sig" LLVM_SLOT="20 -17 -18 -19" conflicts with
    <dev-lang/ghc-9.1:= required by (dev-haskell/cereal-0.5.8.1:0/0.5.8.1::gentoo, ebuild scheduled for merge) USE="-doc -hscolour -profile -test"
    ^             ^^^  


!!! The following update(s) have been skipped due to unsatisfied dependencies
!!! triggered by backtracking:

dev-haskell/text:0
dev-haskell/parsec:0