[GHC] #9009: Confusing error message when loading package with TH

[GHC]

#9009: Confusing error message when loading package with TH
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              Reporter:  jstolarek   |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Package     |          Version:  7.8.2
  system                             |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:  Other       |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by jstolarek):

 Thomie, I haven't tried this with HEAD. With 7.8.3 the problem is of
 course there.

 Here are steps to reproduce:

 1. `cabal get singletons`
 2. `cd singletons-1.0`
 3. edit `singletons.cabal` and remove line 98
 (`Data.Singletons.Single.Monad` from `other-modules` section)
 4. `cabal install`
 5. `ghc Foo.hs` where `Foo.hs` contains:

 {{{#!hs
 {-# LANGUAGE TemplateHaskell, KindSignatures, DataKinds, TypeFamilies,
 ExistentialQuantification #-}
 module Foo where

 import Data.Singletons.TH

 $(promote [d| data N = Z | S N |])
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9009#comment:2>
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