[GHC] #13547: ghc: panic! StgCmmEnv: variable not found

[GHC]

#13547: ghc: panic! StgCmmEnv: variable not found
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        Reporter:  cipher1024        |                Owner:  (none)
            Type:  bug               |               Status:  infoneeded
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
  (CodeGen)                          |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  10158             |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by RyanGlScott):

 Replying to [comment:6 cipher1024]:
 > How do you normally proceed? Is there a better approach to commenting
 out functions until I find one that breaks the compiler?

 That's the approach I use, yes :)

 I did recall that the issue appears when you trim down
 [https://github.com/unitb/literate-
 unitb/blob/d35ae6190407b7579e785db9dac8ef0b62c729eb/src/Document/Phase/Proofs.hs
 Document.Phase.Proofs] to just `liveness`, `stepList`, and `stepList'`
 (you can replace some subexpressions, such as `withCommand "\\safstep" $
 safStep m`, with `undefined` to help eliminate top-level definitions you
 don't need, like `safStep`). But after that point, the issue was tracking
 down all of the types imported from other modules and putting them all in
 one place. That's the point where I gave up, since trying to understand
 the innards of `HasCell`, `Builder`, `LatexParserA`, etc. proved too much
 for my feeble brain.

 > If the fix exists, is there any chance it might get applied to ghc-8.0.1
 and ghc-8.0.2?

 No. GHC 8.2.1 is going to be released soon, so if you help us discover a
 bug that still needs to be fixed, then it would get merged into 8.2.1 at
 the earliest.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13547#comment:7>
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