Setup.lhs problem with absent cabal-doctest

[duog]

I ran into an error in Setup.lhs, where MIN_VERSION_cabal_doctest was undefined. This triggered the #ifdef that seems to be a copy/paste of parts of
https://github.com/phadej/cabal-doctest/blob/master/src/Distribution/Extra/Doctest.hs
However generateBuildModule as defined in Setup.lhs takes 3 parameters, but is called elsewhere in Setup.lhs with 4 parameters. The version in cabal-doctest takes 4 parameters, so I guess you need to redo your copy/paste.

[RyanGlScott]

A little more detail would appreciated, as I have no idea what the error you're referring to is. What steps do you need to perform to reproduce this? Including versions of GHC/build tools would be helpful as well.

[duog]

I am experiencing a type error at https://github.com/ekmett/lens/blob/master/Setup.lhs#L187 when trying to cabal configure on lens master branch. I am using GHC head, or close to it.

MIN_VERSION_cabal_doctest(1,0,0) is 0 for whatever reason, I am sure that's a problem in my environment somewhere.
Hence the CPP in Setup.lhs causes generateBuildModule to be defined at https://github.com/ekmett/lens/blob/master/Setup.lhs#L64 rather than to be imported from cabal-doctest. However the defintions in Setup.lhs and cabal-doctest differ in their arity. generateBuildModule is called with 4 parameters, but defined with 3, boom.

[duog]

I don't have a dev environment on me to check a reproduction right now, but if you can remove cabal-doctest from your package database and cabal configure that would do it. You might have to use a version of cabal-install that doesn't know about setup-depends.

[duog]

I see that ekmetts other packages do a similar thing, but they define generateBuildModule with 4 parameters. Compare:
https://github.com/ekmett/comonad/blob/master/Setup.lhs#L59
https://github.com/ekmett/lens/blob/master/Setup.lhs#L64

[RyanGlScott]

Ah, very nice catch. Thanks!