[commit: haddock] alexbiehl-patch-1, ghc-head, ghc-head1, headdock-library-1.4.5, ie_avails, master, pr-filter-maps, pr/cabal-desc, v2.18, wip/T14529, wip/revert-ttg-2017-11-20, wip/ttg-2017-10-13, wip/ttg-2017-10-31, wip/ttg-2017-11-06, wip/ttg2-2017-11-10, wip/ttg3-2017-11-12, wip/ttg4-constraints-2017-11-13, wip/ttg6-unrevert-2017-11-22: Haddock: Fix broken lazy IO in prologue reading (#615) (b35eed2)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/haddock

On branches: alexbiehl-patch-1,ghc-head,ghc-head1,headdock-library-1.4.5,ie_avails,master,pr-filter-maps,pr/cabal-desc,v2.18,wip/T14529,wip/revert-ttg-2017-11-20,wip/ttg-2017-10-13,wip/ttg-2017-10-31,wip/ttg-2017-11-06,wip/ttg2-2017-11-10,wip/ttg3-2017-11-12,wip/ttg4-constraints-2017-11-13,wip/ttg6-unrevert-2017-11-22
Link       : http://git.haskell.org/haddock.git/commitdiff/b35eed2a9f1c82131f51f55c771ac2372127520d

>---------------------------------------------------------------

commit b35eed2a9f1c82131f51f55c771ac2372127520d
Author: Alex Biehl <alexbiehl at gmail.com>
Date:   Fri May 12 21:02:33 2017 +0200

    Haddock: Fix broken lazy IO in prologue reading (#615)
    
    We previously used withFile in conjunction with hGetContents. The list returned
    by the latter wasn't completely forced by the time we left the withFile block,
    meaning that we would try to read from a closed handle.


>---------------------------------------------------------------

b35eed2a9f1c82131f51f55c771ac2372127520d
 haddock-api/src/Haddock.hs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/haddock-api/src/Haddock.hs b/haddock-api/src/Haddock.hs
index 3971a5b..f0e7e6c 100644
--- a/haddock-api/src/Haddock.hs
+++ b/haddock-api/src/Haddock.hs
@@ -547,9 +547,10 @@ getPrologue :: DynFlags -> [Flag] -> IO (Maybe (MDoc RdrName))
 getPrologue dflags flags =
   case [filename | Flag_Prologue filename <- flags ] of
     [] -> return Nothing
-    [filename] -> withFile filename ReadMode $ \h -> do
+    [filename] -> do
+      h <- openFile filename ReadMode
       hSetEncoding h utf8
-      str <- hGetContents h
+      str <- hGetContents h -- semi-closes the handle
       return . Just $! parseParas dflags str
     _ -> throwE "multiple -p/--prologue options"