[GHC] #8540: Template Haskell handling bug in ghc-7.7.20131115 ?

[GHC]

#8540: Template Haskell handling bug in ghc-7.7.20131115 ?
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        Reporter:  awson             |            Owner:
            Type:  bug               |           Status:  new
        Priority:  normal            |        Milestone:
       Component:  Compiler          |          Version:  7.7
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  Runtime crash     |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:
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Comment (by awson):

 Here is the simplest test case:

 Foo.hs
 {{{
 {-# LANGUAGE TemplateHaskell #-}
 module Foo (foo) where

 import Language.Haskell.TH

 foo :: Q Exp
 foo = [| bar |]

 bar :: Int
 bar = 5
 }}}

 Baz.hs
 {{{
 {-# LANGUAGE TemplateHaskell #-}

 module Baz where

 import Foo

 baz :: Int
 baz = $foo
 }}}

 Current GHC gives
 {{{
 Baz.hs:8:7:
     Can't find interface-file declaration for variable Foo.bar
       Probable cause: bug in .hi-boot file, or inconsistent .hi file
       Use -ddump-if-trace to get an idea of which file caused the error
     In the expression: Foo.bar
     In an equation for `baz': baz = Foo.bar
 }}}
 when compiling Baz.hs.

 But if I explicitly export bar from Foo.hs:
 {{{
 {-# LANGUAGE TemplateHaskell #-}

 module Foo (foo, bar) where

 import Language.Haskell.TH

 foo :: Q Exp
 foo = [| bar |]

 bar :: Int
 bar = 5
 }}}
 current GHC gets happy.

 Older GHCs were able to live without this.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8540#comment:5>
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