[GHC] #9160: Panic: Template variable unbound in rewrite rule

[GHC]

#9160: Panic: Template variable unbound in rewrite rule
-------------------------------------+-------------------------------------
              Reporter:  mietek      |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:  7.8.3
             Component:  Compiler    |          Version:  7.8.2
            Resolution:              |         Keywords:
      Operating System:              |     Architecture:  x86_64 (amd64)
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:  Compile-    |       Blocked By:
  time crash                         |  Related Tickets:  #4524
             Test Case:              |
  indexed_types/should_fail/T9160    |
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------
Changes (by mjo):

 * status:  closed => new
 * resolution:  fixed =>


Comment:

 I'm seeing the same symptoms with 7.8.3:

 {{{
 $ ghc --version
 The Glorious Glasgow Haskell Compilation System, version 7.8.3
 }}}

 Only with -O2 set, again.

 {{{
 $ cd singletons-1.0/
 $ runghc Setup.hs configure --user -O2
 Configuring singletons-1.0...
 $ runghc Setup.hs build
 ...
 [39 of 45] Compiling Data.Singletons.Prelude.List (
 src/Data/Singletons/Prelude/List.hs,
 dist/build/Data/Singletons/Prelude/List.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 7.8.3 for x86_64-unknown-linux):
         Template variable unbound in rewrite rule
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9160#comment:10>
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