`cabal-docspec` fails if it cannot find `~/.cabal/config`

[RyanGlScott]

I am attempting to run cabal-docspec locally on a machine where my cabal configuration is located at ~/.config/cabal/config, which is now the default location with cabal-install-3.10 and later. When I do so, cabal-docspec fails with:

$ cabal-docspec
[   0.00001] ghc.info: ghc
[   0.00034] process.0.start: cwd=/tmp ghc --info
[   0.02450] peu.exception: SomeException
/home/ryanglscott/.cabal/config: withBinaryFile: does not exist (No such file or directory)

Presumably, it's looking for the configuration in ~/.cabal/config instead. Is there a way to tell cabal-docspec to look in a different location?

[RyanGlScott]

There is a way, although it's controlled by the cabal-install-parsers library, not by cabal-docspec itself. If you set the CABAL_CONFIG environment variable, e.g.,

$ export CABAL_CONFIG=~/.config/cabal/config

Then cabal-docspec will behave as expected.

[RyanGlScott]

Also, make sure that your ~/.config/cabal/config file explicitly defines the store-dir location, e.g.,

store-dir: /home/ryanglscott/.local/state/cabal/store

If it doesn't define store-dir, then cabal-install-parsers will default to ~/.cabal/store, which isn't where the cabal store is located by default with cabal-install-parsers-3.10+. This will lead to confusing errors when using cabal-docspec that look like:

[  10.07491] debug: stderr:
<command line>: cannot satisfy -package-id comonad-6-inplace: 
    comonad-6-inplace is unusable due to missing dependencies:
      indexed-traversable-0.1.2.1-0505391f249b00d3d49b7c397ce20702cb416ce0667632bc3d065696e2a95ddb tagged-0.8.8-0a00515bf4d9c16b0038b5a06fbb7b9c3d11beeeb5c2f10e7a03cad02a091e24
    (use -v for more information)

[  10.07607] debug: stdout:

[  10.07617] peu.die: Failure while starting GHCi: ExitFailure 1
proci: canceling
proci: terminating
proci: pid Nothing
proci: waiting for termination

[RyanGlScott]

haskell-CI/haskell-ci#655 is an upstream issue about cabal-install-parsers not supporting XDG-style paths.