Warning: The install command is a part of the legacy v1 style of cabal usage.

Please switch to using either the new project style and the new-install
command or the legacy v1-install alias as new-style projects will become the
default in the next version of cabal-install. Please file a bug if you cannot
replicate a working v1- use case with the new-style commands.

For more information, see: https://wiki.haskell.org/Cabal/NewBuild

Resolving dependencies...
Starting     happy-1.19.11
Building     happy-1.19.11
Completed    happy-1.19.11
Warning: could not create a symlink in /home/builder/.cabal/bin for happy
because the file exists there already but is not managed by cabal. You can
create a symlink for this executable manually if you wish. The executable file
has been installed at
/home/builder/hackage-server/build-cache/tmp-install/bin/happy