[GHC] #14075: GHC panic with parallel make

[GHC]

#14075: GHC panic with parallel make
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        Reporter:  inaki             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.2
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:  hs-boot
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #13803, #13981    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by ezyang):

 In parallel mode I see:

 {{{
 Re-typechecking loop: [F, F]
 compile: input file F.hs
 *** Checking old interface for F (use -ddump-hi-diffs for more details):
 [3 of 4] Compiling F                ( F.hs, F.o )

 }}}

 which is wrong wrong wrong; the retypecheck loop MUST NOT contain F
 (compare with non-parallel output; nothing needs to get retypechecked
 before we do F). So this is definitely a parallel specific bug. Workaround
 should be to not use parallel compilation.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14075#comment:4>
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