[GHC] #7423: panic on typo in deriving clause

[GHC]

#7423: panic on typo in deriving clause
-------------------------+--------------------------------------------------
Reporter:  guest         |          Owner:          
    Type:  bug           |         Status:  new     
Priority:  normal        |      Component:  Compiler
 Version:  7.4.1         |       Keywords:          
      Os:  Linux         |   Architecture:  Other   
 Failure:  None/Unknown  |      Blockedby:          
Blocking:                |        Related:          
-------------------------+--------------------------------------------------
 Consider the following:

 data T = T deriving (eq)

 Note the misspelled lower-case capital - Eq was intended instead. Rather
 than reporting a syntax error, GHC panics:

 mnykanen at localhost$ ghc -v -dcore-lint extest.hs
 Glasgow Haskell Compiler, Version 7.4.1, stage 2 booted by GHC version
 7.0.2
 Using binary package database:
 /home/mnykanen/bin/ghc-7.4.1/lib/ghc-7.4.1/package.conf.d/package.cache
 Using binary package database:
 /home/mnykanen/.ghc/x86_64-linux-7.4.1/package.conf.d/package.cache
 wired-in package ghc-prim mapped to ghc-
 prim-0.2.0.0-c2ff696e5b8ec4d4b2bc2e42085fe471
 wired-in package integer-gmp mapped to integer-
 gmp-0.4.0.0-3cccac07aef8e27023f605c1f45bdf74
 wired-in package base mapped to
 base-4.5.0.0-6db966b4cf8c1a91188e66d354ba065e
 wired-in package rts mapped to builtin_rts
 wired-in package template-haskell mapped to template-
 haskell-2.7.0.0-133c0fdb189e05de22bd926d39f99fe3
 wired-in package dph-seq not found.
 wired-in package dph-par not found.
 Hsc static flags: -static
 *** Chasing dependencies:
 Chasing modules from: *extest.hs
 Stable obj: []
 Stable BCO: []
 Ready for upsweep
   [NONREC
       ModSummary {
          ms_hs_date = Sat Nov 17 10:05:25 EET 2012
          ms_mod = main:Main,
          ms_textual_imps = [import (implicit) Prelude]
          ms_srcimps = []
       }]
 *** Deleting temp files:
 Deleting:
 compile: input file extest.hs
 Created temporary directory: /tmp/ghc2802_0
 *** Checking old interface for main:Main:
 [1 of 1] Compiling Main             ( extest.hs, extest.o )
 *** Parser:
 *** Renamer/typechecker:
 *** Deleting temp files:
 Deleting: /tmp/ghc2802_0/ghc2802_0.s
 Warning: deleting non-existent /tmp/ghc2802_0/ghc2802_0.s
 *** Deleting temp dirs:
 Deleting: /tmp/ghc2802_0
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.4.1 for x86_64-unknown-linux):
         nameModule eq{tv a9I}

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7423>
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