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

Calculating dependencies ... done!
Dependency resolution took 1.71 s (backtrack: 0/20).

[ebuild  N     ] app-text/dos2unix-7.5.7::gentoo  USE="nls -debug -test -verify-sig" 977 KiB
[ebuild  N     ] dev-lang/ghc-9.8.4-r1:0/9.8.4::gentoo  USE="gmp (-big-endian) -doc -elfutils -ghcbootstrap -ghcmakebinary -llvm -numa -profile -test -unregisterised -verify-sig" LLVM_SLOT="20 -17 -18 -19" 238903 KiB
[ebuild  N     ] app-admin/haskell-updater-1.5.0.0::gentoo  45 KiB
[ebuild  N     ] dev-haskell/parsec-3.1.17.0:0/3.1.17.0::gentoo  USE="-doc -hscolour -profile" 38 KiB
[ebuild  N     ] dev-haskell/text-2.1.1:0/2.1.1::gentoo  USE="simdutf -doc -hscolour -profile" 294 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/data-default-class-0.1.2.0:0/0.1.2.0::gentoo  USE="-doc -hscolour -profile" 3 KiB
[ebuild  N     ] dev-haskell/old-locale-1.0.0.7:0/1.0.0.7::gentoo  USE="-doc -hscolour -profile" 4 KiB
[ebuild  N     ] dev-haskell/dlist-1.0:0/1.0::gentoo  USE="-doc -hscolour -profile -test -werror" 23 KiB
[ebuild  N     ] dev-haskell/data-default-instances-containers-0.0.1:0/0.0.1::gentoo  USE="-doc -hscolour -profile" 2 KiB
[ebuild  N     ] dev-haskell/data-default-instances-dlist-0.0.1:0/0.0.1::gentoo  USE="-doc -hscolour -profile" 2 KiB
[ebuild  N     ] dev-haskell/data-default-instances-old-locale-0.0.1:0/0.0.1::gentoo  USE="-doc -hscolour -profile" 2 KiB
[ebuild  N     ] dev-haskell/data-default-0.7.1.1:0/0.7.1.1::gentoo  USE="-doc -hscolour -profile" 2 KiB

Total: 14 packages (14 new), Size of downloads: 240906 KiB

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

dev-haskell/data-default-class:0

  (dev-haskell/data-default-class-0.2.0.0:0/0.2.0.0::gentoo, ebuild scheduled for merge) USE="-doc -hscolour -profile" conflicts with
    <dev-haskell/data-default-class-0.2:= required by (dev-haskell/data-default-instances-containers-0.0.1:0/0.0.1::gentoo, ebuild scheduled for merge) USE="-doc -hscolour -profile"
    ^                               ^^^  

dev-haskell/data-default:0

  (dev-haskell/data-default-0.8.0.1:0/0.8.0.1::gentoo, ebuild scheduled for merge) USE="-doc -hscolour -profile -test" conflicts with
    =dev-haskell/data-default-0.7.1.1