[GHC] #2030: GHC internal error: `m' is not in scope

[GHC]

#2030: GHC internal error: `m' is not in scope
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 Reporter:  ToRA                     |          Owner:                
     Type:  bug                      |         Status:  new           
 Priority:  normal                   |      Milestone:                
Component:  Compiler (Type checker)  |        Version:  6.8.2         
 Severity:  normal                   |     Resolution:                
 Keywords:                           |     Difficulty:  Unknown       
 Testcase:                           |   Architecture:  x86_64 (amd64)
       Os:  Linux                    |  
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Comment (by ToRA):

 Further information.

 6.6.1 will compile it. Also brings down 6.8.1

 >ghc-6.8.1 -v -c /tmp/Bug.hs
 Glasgow Haskell Compiler, Version 6.8.1, for Haskell 98, stage 2 booted by
 GHC version 6.6.1
 Using package config file: /home/tora/lib/ghc-6.8.1/package.conf
 hiding package X11-1.2.3.1 to avoid conflict with later version X11-1.4.0
 wired-in package base mapped to base-3.0.0.0
 wired-in package rts mapped to rts-1.0
 wired-in package haskell98 mapped to haskell98-1.0.1.0
 wired-in package template-haskell mapped to template-haskell-2.2.0.0
 wired-in package ndp not found.
 Hsc static flags: -static
 Created temporary directory: /tmp/ghc2997_0
 *** Checking old interface for main:Bug:
 *** Parser:
 *** Renamer/typechecker:

 /tmp/Bug.hs:36:24:
     GHC internal error: `m' is not in scope
     In the type `m Safety'
     In the type `Alt -> m Safety'
     In the type signature for `isSafeAlt':
       isSafeAlt :: Alt -> m Safety
 *** Deleting temp files:
 Deleting: /tmp/ghc2997_0/ghc2997_0.s
 Warning: deleting non-existent /tmp/ghc2997_0/ghc2997_0.s
 *** Deleting temp dirs:
 Deleting: /tmp/ghc2997_0

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2030#comment:4>
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