[GHC] #14880: GHC panic: updateRole

[GHC]

#14880: GHC panic: updateRole
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #15076            |  Differential Rev(s):  Phab:D4769
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by goldfire):

 I might have time to take a look at this, but I'll need a bit more
 direction. You say that you might have missed something -- what two
 branches can I compare to assess that?

 As for the one-line change: it's seems conceivable that the change could
 have a measurable performance impact. Have you tested the change,
 independent of anything else? If the fix makes performance worse, that
 would be an insight, because the `acc` check looks like it's only an
 optimization, not an essential check for correctness.

 Thanks!

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14880#comment:106>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler