Preserving empty lines in free text fields

[jlwoodwa]

cabal-fmt strips empty lines from all fields. However, with the new free text rules (haskell/cabal#5981), empty lines seem to be the only way to break paragraphs in the description field, etc. (Previously, a line containing a single period would do the trick, and cabal-fmt preserved this.)

Can cabal-fmt be changed to preserve empty lines in free text fields?

[phadej]

Yes, that would be good to fix.

I'm not sure where (and why) the empty lines are stripped.

[shlevy]

@phadej Would this be a hard fix? Can you point to where to look?

[phadej]

@shlevy I suspect it's an issue in Cabal-syntax. See #86

The traceShowId prints `"First Paragraph\nSecond Paragraph", i.e. there is a missing line feed already.

https://github.com/haskell/cabal/blob/f01e000b92ddf8cf04a175228e0758fafb732a4d/Cabal-syntax/src/Distribution/FieldGrammar/Parsec.hs#L404 is a suspect. It makes the indentation be right, but it forgets to insert empty lines when the are between input FieldLines (i.e. positionRow differ by two or more).

[phadej]

Actually no. The issue is in cabal-fmt (but Cabal-syntax does not have a bug)

[phadej]

The #86 seems to work, I'll cleanup it later this month