[GHC] #7791: Bad error message when strictness annotations are used without BangPatterns pragma

[GHC]

#7791: Bad error message when strictness annotations are used without BangPatterns
pragma
----------------------------------------------+-----------------------------
Reporter:  manzyuk                            |          Owner:                
    Type:  bug                                |         Status:  new           
Priority:  normal                             |      Component:  Compiler      
 Version:  7.4.1                              |       Keywords:                
      Os:  Linux                              |   Architecture:  x86_64 (amd64)
 Failure:  Incorrect warning at compile-time  |      Blockedby:                
Blocking:                                     |        Related:                
----------------------------------------------+-----------------------------
 Loading the program

 {{{
 powers n = go 1 where
   go !k = k : go (k * n)
 }}}

 into GHCi results in an error:

 {{{
 *Main> :load "/home/manzyuk/tmp/example.hs"
 [1 of 1] Compiling Main             ( /home/manzyuk/tmp/example.hs,
 interpreted )

 /home/manzyuk/tmp/example.hs:1:12: Not in scope: `go'
 Failed, modules loaded: none.
 }}}

 The error message is plain wrong.  The problem is fixed by enabling
 {{{BangPatterns}}} pragma.  It would be nice if GHC could suggest that
 like it does in many other similar cases.

 {{{
 $ ghc --version
 The Glorious Glasgow Haskell Compilation System, version 7.4.1
 $ uname -a
 Linux paddy 2.6.32-45-generic #104-Ubuntu SMP Tue Feb 19 21:20:09 UTC 2013
 x86_64 GNU/Linux
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7791>
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