`cabal format` is not listed in --help message

[osa1]

Any ideas why this command is hidden? I recently discovered this and I think it's very useful.

[23Skidoo]

There are some bugs, e.g. #2353.

[23Skidoo]

Fixing this is trivial, but we'll need to fix #2661 and #2681 first before making this feature public. See discussion in #2607, specifically https://github.com/haskell/cabal/pull/2607#issuecomment-113414514.

[gbaz]

It looks like both the referenced bugs were fixed. Are there any further blockers?

[gbaz]

Here's a script I bodged together from the one in the other ticket, but updated for the latest cabal.

module Main (main) where

import Control.Monad
import Control.Applicative
import Distribution.Verbosity
import Distribution.Client.IndexUtils
import qualified Distribution.PackageDescription.Parsec as PackageDesc.Parse
import Distribution.PackageDescription.PrettyPrint
import Distribution.ParseUtils
import qualified Data.ByteString.Char8 as BS
import Data.List

check :: FilePath -> IO ()
check cabal = do
  print cabal
  cabalfile <- BS.readFile cabal
  let desc1 = parsePackageDescription  cabalfile
  case desc1 of
    Nothing -> print "failparse"
    Just desc -> do
      let desc' = parsePackageDescription $ BS.pack (showGenericPackageDescription desc)
      when (Just desc /= desc') $ do
        print $  Just desc
        print $  desc'
        fail cabal

parsePackageDescription content = either (const Nothing) Just $ snd $ PackageDesc.Parse.runParseResult $ PackageDesc.Parse.parseGenericPackageDescription $ content

myFilter x  = not $ "lambdaBase" `isInfixOf` x || "wiringPi" `isInfixOf` x || "constrained-monads" `isInfixOf` x

main :: IO ()
main = do
  -- Generate listing with
  -- find . -type f -name '*.cabal' > cabal-files
  cabalFiles <- Prelude.filter myFilter . Prelude.lines <$> Prelude.readFile "cabal-files"
  mapM_ check cabalFiles

The errors it seems to run into are all about round-trips with character encodings.

E.g. in the original you have something like copyright = "2016 Donnacha Ois\237n Kidney", and in the processed file you have copyright = "2016 Donnacha Ois\65533 Kidney"