haddock fails with "internal error: spliceURL UnhelpfulSpan"

This bug has already been submitted on the haddock trac system.

http://trac.haskell.org/haddock/ticket/207

I am reflecting it here as the bug is still valid as of the haddock version 2.11.0 included in ghc 7.4.2.

Symptom: if a declaration is missing a type signature, as in

module HaddockBug (
  haddockbug
  ) where

-- missing type signature
haddockbug x = x + 1

haddock called with the command line

haddock -h HaddockBug.hs --source-entity=HaddockBug.html#line-%L 

fails with

internal error: spliceURL UnhelpfulSpan

In case it is of any help, here is the patch I am using to overcome the problem.

diff -r -u haddock-ghc-7.4.2/src/Haddock/Interface/Create.hs haddock/src/Haddock/Interface/Create.hs
--- haddock-ghc-7.4.2/src/Haddock/Interface/Create.hs   2012-08-30 10:12:42.149210546 -0400
+++ haddock/src/Haddock/Interface/Create.hs     2012-08-30 10:13:08.745620048 -0400
@@ -19,6 +19,7 @@
 import Haddock.Utils
 import Haddock.Convert
 import Haddock.Interface.LexParseRn
+import Haddock.Interface.Rename
 
 import qualified Data.Map as M
 import Data.Map (Map)
@@ -41,6 +42,25 @@
 import TcRnTypes
 import FastString (unpackFS)
 
+-- | To filter out the ExportItem's that are UnhelpfulSpan.
+isHelpfulSpan :: ExportItem Name -> ErrMsgM Bool
+isHelpfulSpan l = case l of
+     (ExportDecl (L (UnhelpfulSpan _) _) _ _ _) -> do
+       tell [concat ["Warning: ", 
+                     extractName l, 
+                     " is exported but does not have a type signature. ",
+                     "Skipping it..."]]
+       return False
+     _ -> return True
+  where
+    
+  -- This is reusing renameExportItem and runRnFM from
+  -- Haddock.Interface.Rename.
+  --
+  -- We use an empty environment for simplicity: for the sake
+  -- of the warning, we know in which module this takes place.
+  extractName :: ExportItem Name -> String
+  extractName e = show $ getOccString $ head $ snd $ runRnFM M.empty $ renameExportItem e
 
 -- | Use a 'TypecheckedModule' to produce an 'Interface'.
 -- To do this, we need access to already processed modules in the topological
@@ -91,6 +111,7 @@
   let warningMap = mkWarningMap warnings gre exportedNames
   exportItems <- mkExportItems modMap mdl warningMap gre exportedNames decls maps exports
                    instances instIfaceMap dflags
+                 >>= (liftErrMsg . filterM isHelpfulSpan)
 
   let visibleNames = mkVisibleNames exportItems opts
 
diff -r -u haddock-ghc-7.4.2/src/Haddock/Interface/Rename.hs haddock/src/Haddock/Interface/Rename.hs
--- haddock-ghc-7.4.2/src/Haddock/Interface/Rename.hs   2012-08-30 10:12:42.149210546 -0400
+++ haddock/src/Haddock/Interface/Rename.hs     2012-08-29 17:12:47.812702645 -0400
@@ -9,7 +9,7 @@
 -- Stability   :  experimental
 -- Portability :  portable
 -----------------------------------------------------------------------------
-module Haddock.Interface.Rename (renameInterface) where
+module Haddock.Interface.Rename (renameInterface,renameExportItem,runRnFM) where
 
 
 import Haddock.GhcUtils

Trac metadata

Trac field	Value
Version	7.4.2
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Documentation
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