[GHC] #13710: panic with boot and -jX

[GHC]

#13710: panic with boot and -jX
-------------------------------------+-------------------------------------
        Reporter:  pacak             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1-rc2
      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:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by pacak):

 Panic in rc2, successfull compilation in 8.0 and 7.10

 {{{
 % cat A.hs
 {-# LANGUAGE RecordWildCards #-}

 module A where

 import B

 type E = ()

 yay :: Maybe ()
 yay = do
   H{..} <- undefined
   undefined
 }}}

 {{{
 % cat A.hs-boot
 module A ( E ) where
 type E = ()
 }}}

 {{{
 % cat B.hs
 module B where
 import {-# SOURCE #-} A
 data F a = F a
 type G = F (Maybe E)
 data H = H { h :: {-# UNPACK #-} !G }
 }}}


 rc2, -j1
 {{{
 % rm *.hi* *.o* ; ghc -j1 -O2 A.hs
 [1 of 3] Compiling A[boot]          ( A.hs-boot, A.o-boot )
 [2 of 3] Compiling B                ( B.hs, B.o )
 [3 of 3] Compiling A                ( A.hs, A.o )
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.2.0.20170503 for x86_64-unknown-linux):
         tcIfaceGlobal (local): not found
   You are in a maze of twisty little passages, all alike.
   While forcing the thunk for TyThing E
   which was lazily initialized by initIfaceCheck typecheckLoop,
   I tried to tie the knot, but I couldn't find E
   in the current type environment.
   If you are developing GHC, please read Note [Tying the knot]
   and Note [Type-checking inside the knot].
   Consider rebuilding GHC with profiling for a better stack trace.
   Contents of current type environment: []
   Call stack:
       CallStack (from HasCallStack):
         prettyCurrentCallStack, called at
 compiler/utils/Outputable.hs:1134:58 in ghc:Outputable
         callStackDoc, called at compiler/utils/Outputable.hs:1138:37 in
 ghc:Outputable
         pprPanic, called at compiler/iface/TcIface.hs:1689:23 in
 ghc:TcIface

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}


 rc2, -j2  - note - error message is slightly different + it's in color
 {{{
 % rm *.hi* *.o* ; ghc -j2 -O2 A.hs
 [1 of 3] Compiling A[boot]          ( A.hs-boot, A.o-boot )
 [2 of 3] Compiling B                ( B.hs, B.o )
 [3 of 3] Compiling A                ( A.hs, A.o )

 <no location info>: error:
     ghc: panic! (the 'impossible' happened)
   (GHC version 8.2.0.20170503 for x86_64-unknown-linux):
         tcIfaceGlobal (local): not found
   You are in a maze of twisty little passages, all alike.
   While forcing the thunk for TyThing E
   which was lazily initialized by initIfaceCheck typecheckLoop,
   I tried to tie the knot, but I couldn't find E
   in the current type environment.
   If you are developing GHC, please read Note [Tying the knot]
   and Note [Type-checking inside the knot].
   Consider rebuilding GHC with profiling for a better stack trace.
   Contents of current type environment: []
   Call stack:
       CallStack (from HasCallStack):
         prettyCurrentCallStack, called at
 compiler/utils/Outputable.hs:1134:58 in ghc:Outputable
         callStackDoc, called at compiler/utils/Outputable.hs:1138:37 in
 ghc:Outputable
         pprPanic, called at compiler/iface/TcIface.hs:1689:23 in
 ghc:TcIface

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug
 }}}

 ghc 8.0:
 {{{
 % rm *.hi* *.o* ; ghc -j1 -O2 A.hs
 [1 of 3] Compiling A[boot]          ( A.hs-boot, A.o-boot )
 [2 of 3] Compiling B                ( B.hs, B.o )
 [3 of 3] Compiling A                ( A.hs, A.o )
 }}}

 {{{
 % rm *.hi* *.o* ; ghc -j2 -O2 A.hs
 [1 of 3] Compiling A[boot]          ( A.hs-boot, A.o-boot )
 [2 of 3] Compiling B                ( B.hs, B.o )
 [3 of 3] Compiling A                ( A.hs, A.o )
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13710#comment:8>
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