/usr/lib/ghc-doc/hoogle/gnuidn.txt is in libghc-gnuidn-doc 0.2-4build1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-gnuidn-doc/html/gnuidn.txt
/usr/lib/ghc-doc/hoogle/../../../share/doc/libghc-gnuidn-doc/html/gnuidn.txt