[GHC] #786: bugs around tagToEnum#

[GHC]

#786: bugs around tagToEnum#
----------------------------------------+-----------------------------------
  Reporter:  Bulat.Ziganshin at gmail.com  |          Owner:         
      Type:  bug                        |         Status:  new    
  Priority:  normal                     |      Milestone:         
 Component:  Compiler                   |        Version:  6.4.2  
  Severity:  normal                     |     Resolution:         
  Keywords:                             |             Os:  Unknown
Difficulty:  Unknown                    |   Architecture:  Unknown
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Comment (by simonpj):

 Unboxable.hs: we should fail more gracefully. Problem is that tagToEnum#
 is used at a polymorphic type:
 {{{
 ghc-6.4.2: panic! (the `impossible' happened, GHC version 6.4.2):
         splitTyConApp a{tv a17D}
 }}}
 Unboxable3.hs: Same, but this time tagToEnum# is used at Int, which isn't
 in Enum:
 {{{
 Unboxable3.o(.text+0x9): In function `s1tx_info':
 : undefined reference to `GHCziBase_Int_closure_tbl'
 collect2: ld returned 1 exit status
 }}}
 Unboxable2.hs: this is an NCG bug.
 {{{
 /tmp/ghc11494.s: Assembler messages:
 /tmp/ghc11494.s:83: Error: junk `naughty I386 byte register' after
 expression
 /tmp/ghc11494.s:83: Error: too many memory references for `mov'
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/786>
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