[Hackage] #546: look for haddock in ghc's bin dir before using findExecutable

[Hackage]

#546: look for haddock in ghc's bin dir before using findExecutable
------------------------------+---------------------------------------------
  Reporter:  duncan           |        Owner:           
      Type:  defect           |       Status:  new      
  Priority:  normal           |    Milestone:  Cabal-1.8
 Component:  Cabal library    |      Version:  1.6.0.2  
  Severity:  normal           |     Keywords:           
Difficulty:  easy (<4 hours)  |   Ghcversion:           
  Platform:  Windows          |  
------------------------------+---------------------------------------------
 With current versions of haddock it's important to pick a version that's
 consistent with the ghc in use. Normally we use
 `System.Directory.findExecutable` to find tools like `haddock`. However on
 Windows, the Win32 `SearchPath` function looks not just in the `%PATH%`.
 It looks first in the directory where the .exe of the current process
 lives (which might either be `runghc.exe` or it might be `cabal.exe`) and
 only secondarily in the `%PATH%`.

 So, for ghc, Cabal should look for haddock first in ghc's bin dir and then
 if it's not there, use `findExecutable` to look in various other places.

 Reported originally on the [http://haskell.org/pipermail/cabal-
 devel/2009-April/005161.html mailing list] and as a
 [http://hackage.haskell.org/trac/ghc/ticket/3186 ghc ticket].

-- 
Ticket URL: <http://hackage.haskell.org/trac/hackage/ticket/546>
Hackage <http://haskell.org/cabal/>
Hackage: Cabal and related projects