[GHC] #16057: GHC 8.6.3 hangs with Template Haskell on Windows 10

[GHC]

#16057: GHC 8.6.3 hangs with Template Haskell on Windows 10
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        Reporter:  gizmo.mk0         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:
       Component:  Template Haskell  |              Version:  8.6.3
      Resolution:                    |             Keywords:
Operating System:  Windows           |         Architecture:  x86
 Type of failure:  Compile-time      |            Test Case:
  crash or panic                     |
      Blocked By:                    |             Blocking:
 Related Tickets:  #16071            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 This looks serious.  Prevents Agda compiling (see #16071).  Tamar are you
 happy to dig or do you need help?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16057#comment:8>
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