[GHC] #11371: Bogus in-scope set in substitutions

[GHC]

#11371: Bogus in-scope set in substitutions
-------------------------------------+-------------------------------------
        Reporter:  simonpj           |                Owner:  niteria
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11360            |  Differential Rev(s):  phab:D1792
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by thomie):

 niteria: this commit is causing some test failures on Travis:

 {{{
 Unexpected failures:
    ghci.debugger/scripts           T2740 [bad stderr] (ghci)
    ghci.debugger/scripts           break001 [bad stderr] (ghci)
    ghci.debugger/scripts           break003 [bad stderr] (ghci)
    ghci.debugger/scripts           break005 [bad stderr] (ghci)
    ghci.debugger/scripts           break006 [bad stderr] (ghci)
    ghci.debugger/scripts           break009 [bad stdout] (ghci)
    ghci.debugger/scripts           break010 [bad exit code] (ghci)
    ghci.debugger/scripts           break011 [bad stdout] (ghci)
    ghci.debugger/scripts           break012 [bad stderr] (ghci)
    ghci.debugger/scripts           break017 [bad stdout] (ghci)
    ghci.debugger/scripts           break018 [bad stderr] (ghci)
    ghci.debugger/scripts           break020 [bad stderr] (ghci)
    ghci.debugger/scripts           break021 [bad stderr] (ghci)
    ghci.debugger/scripts           break026 [bad stderr] (ghci)
    ghci.debugger/scripts           break027 [bad stderr] (ghci)
    ghci.debugger/scripts           break028 [bad stderr] (ghci)
    ghci.debugger/scripts           dynbrk002 [bad stderr] (ghci)
    ghci.debugger/scripts           hist001 [bad stderr] (ghci)
    ghci.debugger/scripts           print003 [bad stderr] (ghci)
    ghci.debugger/scripts           print005 [bad stderr] (ghci)
    ghci.debugger/scripts           print006 [bad stderr] (ghci)
    ghci.debugger/scripts           print008 [bad stderr] (ghci)
    ghci.debugger/scripts           print010 [bad stderr] (ghci)
    ghci.debugger/scripts           print018 [bad stderr] (ghci)
    ghci.debugger/scripts           print019 [bad stderr] (ghci)
    ghci.debugger/scripts           print022 [bad stderr] (ghci)
    ghci.debugger/scripts           print025 [bad stderr] (ghci)
    ghci.debugger/scripts           print029 [bad stderr] (ghci)
    ghci.debugger/scripts           print030 [bad stderr] (ghci)
    ghci.debugger/scripts           print031 [bad stderr] (ghci)
    ghci.debugger/scripts           print032 [bad stderr] (ghci)
    ghci.debugger/scripts           result001 [bad stderr] (ghci)
    ghci.debugger/scripts/break022  break022 [bad stderr] (ghci)
    indexed-types/should_compile    T3023 [exit code non-0] (normal)
    overloadedrecflds/ghci          overloadedlabelsghci01 [bad stdout]
 (ghci)
    polykinds                       T6015 [exit code non-0] (normal)
    polykinds                       T6015a [exit code non-0] (normal)
    polykinds                       T6068 [bad stderr] (ghci)
    polykinds                       T7332 [exit code non-0] (normal)
    typecheck/should_compile        T4969 [exit code non-0] (normal)
    typecheck/should_compile        tc125 [exit code non-0] (normal)
    typecheck/should_compile        tc126 [exit code non-0] (normal)
    typecheck/should_compile        tc152 [exit code non-0] (normal)
    typecheck/should_compile        tc180 [exit code non-0] (normal)
    typecheck/should_compile        tc187 [exit code non-0] (normal)
    typecheck/should_fail           tcfail093 [exit code non-0] (normal)
 }}}


 Here's one of them:
 {{{
 ghc-stage2: panic! (the 'impossible' happened)
   (GHC version 8.1.20160119 for x86_64-unknown-linux):
         ASSERT failed!
   CallStack (from ImplicitParams):
   assertPprPanic, called at compiler/types/TyCoRep.hs:1827:61 in
 ghc:TyCoRep
   substTy, called at compiler/typecheck/FunDeps.hs:289:35 in ghc:FunDeps
   in_scope InScope [a3vr :-> k_a3vr, a3vs :-> a_a3vs,
                     a3wU :-> t_a3wU[tau:3], a3wV :-> t_a3wV[tau:3]]
   tenv [a3vr :-> TYPE t_a3wU[tau:3], a3vs :-> t_a3wV[tau:3]]
   cenv []
   ty b_a3vt
   needInScope [a3vt :-> b_a3vt]

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

 }}}

 See: https://s3.amazonaws.com/archive.travis-ci.org/jobs/103319396/log.txt

 These are relevant settings that Travis uses:
 {{{
 GhcStage2HcOpts += -DDEBUG
 DYNAMIC_GHC_PROGRAMS = NO
 GhcLibWays = v
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11371#comment:6>
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