After today's ghc-8.4.3 update: >>> Configuring source in /var/tmp/portage/dev-haskell/hscolour-1.24.4/work/hscolour-1.24.4 ... [0/92325] * Using cabal-1.24.2.0. * Prepending /usr/lib64/ghc-8.4.3 to LD_LIBRARY_PATH /usr/bin/ghc -package Cabal-1.24.2.0 --make /var/tmp/portage/dev-haskell/hscolour-1.24.4/work/hscolour-1.24.4/Setup.hs -j6 +RTS -A256M -qb0 -RTS -threaded -dynamic -o setup <command line>: cannot satisfy -package Cabal-1.24.2.0 (use -v for more information) /usr/bin/ghc -package Cabal-1.24.2.0 --make /var/tmp/portage/dev-haskell/hscolour-1.24.4/work/hscolour-1.24.4/Setup.hs -j6 +RTS -A256M -qb0 -RTS -threaded -o setup <command line>: cannot satisfy -package Cabal-1.24.2.0 (use -v for more information) * ERROR: dev-haskell/hscolour-1.24.4::haskell failed (configure phase): * compiling /var/tmp/portage/dev-haskell/hscolour-1.24.4/work/hscolour-1.24.4/Setup.hs failed * * Call stack: * ebuild.sh, line 124: Called src_configure * environment, line 2715: Called haskell-cabal_src_configure '--ghc-options=-rtsopts' * environment, line 1929: Called cabal-bootstrap * environment, line 393: Called die * The specific snippet of code: * } || make_setup "$@" || die "compiling ${setupmodule} failed";
ghc-8.4.3 will require cabal-2.2.0.1 or later installed.
My point is, that emerge is unable to detect that. Maybe because the Cabal requirement isn't known... After manually upgrading dev-haskell/cabal-2.2.0.1:0/2.2.0.1::haskell [1.24.2.0:0/1.24.2.0::haskell] first, world upgrade was finally successful.