`make style` fails "The GHC parser (in Haddock mode) failed"

[mpickering]

If I try to run the make style rule to apply the formatter to all my files then I get:

[nix-shell:~/cabal]$ make style
cabal-install/src/Distribution/Client/Semaphore/System.hs:66:1
  The GHC parser (in Haddock mode) failed:
  [GHC-58481] parse error (possibly incorrect indentation or mismatched brackets)
make: *** [Makefile:22: style] Error 102

It also seems to apply formatting to a lot of files which I haven't modified.

[ffaf1]

It also seems to apply formatting to a lot of files which I haven't modified.

As per Code Style, try make style-modified.

[ulysses4ever]

Do you use fourmolu of the correct version? (0.12)

[mpickering]

How do I know the correct version? Perhaps a check in the script would be good to ensure that.

[ulysses4ever]

It's documented in CONTRIBUTING.md (under the very section that was referenced above be y ffaf1).

A check would be terrific, indeed.

[ulysses4ever]

Should we close this?