Pretty-printer loses necessary quotes in ghc-options

[peti]

The Cabal file http://hackage.haskell.org/package/serversession-backend-persistent-1.0/serversession-backend-persistent.cabal defines the following ghc-options flags:

ghc-options:     -Wall -threaded "-with-rtsopts=-N -s -M1G -c" -rtsopts

When round-tripped through the Cabal library, however, the outcome will be:

ghc-options: -Wall -threaded -with-rtsopts=-N -s -M1G -c -rtsopts

The quotation marks -- which are essential for the build to succeed -- are lost.

To reproduce this error, process the Cabal file given above with the following code:

import Distribution.PackageDescription.Parse
import Distribution.PackageDescription.PrettyPrint
import Distribution.Verbosity
import System.Environment

main :: IO ()
main = getArgs >>= mapM_ (\cabalFile -> readPackageDescription silent cabalFile >>= writeGenericPackageDescription cabalFile)

This error occurs with Cabal-1.22.2.0, but older versions (like Cabal 1.20.x) seem to have the same issue.

[peti]

This bug is still present in current Git versions of Cabal 1.25.0.0. 😞

[sopvop]

I think this is a the relevant line for Parsec based parser.
And this one is for current parser.
I think conditionally Showing each arg as a haskell string on any isSpace predicate should fix this problem.

[23Skidoo]

/cc @phadej