[GHC] #12630: Assertion failed with BuildFlavour = devel2

[GHC]

#12630: Assertion failed with  BuildFlavour = devel2
-------------------------------------+-------------------------------------
        Reporter:  pacak             |                Owner:
            Type:  bug               |               Status:  merge
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash                              |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by pacak):

 Right, picking 15fc52819c to 8.0 branch fixes the issue.

 Btw, right now I'm debugging one more issue that causes assertion failure
 with devel2 and it's still the case in 8.0 branch. At the moment smallest
 sample is down to 8 files with no external dependencies other than
 bytestring. I can try reducing it further but it's going hard.


 it's a sample for that new panic:

 {{{
   (GHC version 8.0.1.20161022 for x86_64-unknown-linux):
         ASSERT failed!
   CallStack (from HasCallStack):
   assertPprPanic, called at compiler/types/TyCoRep.hs:2012:56 in
 ghc:TyCoRep
   checkValidSubst, called at compiler/types/TyCoRep.hs:2048:17 in
 ghc:TyCoRep
   substTy, called at compiler/simplCore/SimplEnv.hs:696:18 in ghc:SimplEnv
   in_scope InScope [00 :-> wild_00, Xw :-> wild_Xw, XD :-> wild_XD,
                     XH :-> wild1_XH, XaWP :-> msg0_XaWP, a4vA :-> s'_a4vA,
                     a4Db :-> ds2_a4Db, a4Dd :-> ipv_a4Dd, a4De :->
 ipv1_a4De,
                     a6eU :-> t'_a6eU, a6eV :-> pos'_a6eV, a6eW :->
 more'_a6eW,
                     a6eX :-> a1_a6eX, d4gB :-> dt_d4gB, d4gC :-> dt1_d4gC,
                     d4gD :-> dt2_d4gD, d4gE :-> dt3_d4gE, d4gF :->
 dt4_d4gF,
                     d4gG :-> dt5_d4gG, rdYv :-> decodeOTCLine, reHX :->
 $trModule,
                     s6ZQ :-> nt1_s6ZQ, s6ZS :-> ipv1_s6ZS, seJM :->
 $trModule_seJM,
                     seJN :-> $trModule_seJN, seJU :-> lvl_seJU, seJY :->
 lvl_seJY,
                     seOl :-> $wsucc_seOl, seOu :-> $wdecodeOTCLine_seOu,
                     sePd :-> lvl_sePd, sePe :-> lvl_sePe, sePf :->
 lvl_sePf,
                     sePg :-> lvl_sePg, sePh :-> lvl_sePh, sePi :->
 lvl_sePi,
                     sePk :-> lvl_sePk, sePl :-> lvl_sePl, sePm :->
 lvl_sePm,
                     sePn :-> lvl_sePn, sePp :-> fail_sePp, sePq :->
 lvl_sePq,
                     sePr :-> lvl_sePr, sePs :-> lvl_sePs, sePt :->
 lvl_sePt,
                     sePu :-> lvl_sePu, sePv :-> lvl_sePv, sePw :->
 lvl_sePw,
                     seQ0 :-> sc_seQ0, seQ1 :-> sc_seQ1, seQ2 :-> sc_seQ2,
                     seQ3 :-> sc_seQ3, seQ7 :-> sc_seQ7, seQa :->
 $s$wsucc_seQa]
   tenv []
   tenvFVs []
   cenv [seQ6 :-> sg_seQ6]
   cenvFVs [seQ6 :-> sg_seQ6]
   tys [ByteString]
   cos []
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12630#comment:8>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler