Man page is reffering to non-existing PDF files.
The GHC man page states
Extensive documentation is available in various other formats including PDF and HTML; see below.
However, there is no further reference to these documents. We could, for example, give the link to the latest online documentation:
https://downloads.haskell.org/ghc/latest/docs/html/
or
https://downloads.haskell.org/ghc/latest/docs/users_guide.pdf
Thank you!