[GHC] #14075: GHC panic with parallel make

[GHC]

#14075: GHC panic with parallel make
-------------------------------------+-------------------------------------
        Reporter:  inaki             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:
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:                    |
-------------------------------------+-------------------------------------
Changes (by RyanGlScott):

 * cc: ezyang (added)
 * priority:  normal => high
 * milestone:   => 8.4.1


Comment:

 This is a regression from GHC 8.0.2:

 {{{
 $ /opt/ghc/8.0.2/bin/ghc -j2 -fforce-recomp F O V
 [1 of 4] Compiling O                ( O.hs, O.o )
 [2 of 4] Compiling F[boot]          ( F.hs-boot, F.o-boot )
 [3 of 4] Compiling F                ( F.hs, F.o )

 F.hs-boot:7:1: error:
     ‘F.F’ is exported by the hs-boot file, but not exported by the module

 F.hs:1:1: error:
     instance O.O F.F -- Defined at F.hs-boot:8:10
       is defined in the hs-boot file, but not in the module itself
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14075#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler