#2584: Pretty printing of types with HsDocTy goes wrong
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Reporter: NeilMitchell | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.9 | Severity: major
Keywords: | Testcase:
Architecture: Unknown | Os: Unknown
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Pretty printing of type signatures containing HsDocTy goes wrong in HEAD.
This manifests itself as serious bugs in both Haddock and Hoogle. Because
the bug causes Haddock generated documentation to be wrong, I've marked
the severity as major.
Take the following file:
{{{
{-# LANGUAGE FlexibleInstances #-}
import GHC
import SrcLoc
import Outputable
main = do
putStrLn $ out $ HsFunTy fun fun
putStrLn $ out $ HsFunTy (doc fun) fun
reL = L undefined
out x = showSDoc $ ppr x
fun = reL $ HsFunTy (reL $ HsTyVar "a") (reL $ HsTyVar "b")
doc = reL . flip HsDocTy undefined
instance OutputableBndr [Char] where
pprBndr _ x = text x
}}}
The output is:
{{{
C:\Neil>runghc "-package ghc" test2.hs
([a] -> [b]) -> [a] -> [b]
[a] -> [b] <document comment> -> [a] -> [b]
}}}
Note that the first line (correctly) brackets the type signature, but that
the second (incorrectly) omits the brackets. I suggest a change to the
pretty printer to ignore HsTyDoc when determining where to insert brackets
- or even removing the pretty printing of HsTyDoc entirely.
-- Neil
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2584>
GHC <http://www.haskell.org/ghc/>
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