[GHC] #12682: ASSERT failures in testsuite

[GHC]

#12682: ASSERT failures in testsuite
-------------------------------------+-------------------------------------
           Reporter:  simonpj        |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 Joachim [https://mail.haskell.org/pipermail/ghc-
 devs/2016-October/013000.html writes]:
 our secondary CI infrastructure is in bad shape since a week.

 The first push that broke it was the one ending with commit fc4ef66 by
 SPJ:

 * fc4ef66 - Comments only (vor 7 Tagen)<Simon Peyton Jones>
 * b612da6 - Fix impredicativity (again) (vor 7 Tagen)<Simon Peyton Jones>
 * 3012c43 - Add Outputable Report in TcErrors (vor 7 Tagen)<Simon Peyton
 Jones>
 * 66a8c19 - Fix a bug in occurs checking (vor 7 Tagen)<Simon Peyton Jones>
 * 2fbfbca - Fix desugaring of pattern bindings (again) (vor 7 Tagen)<Simon
 Peyton Jones>
 * 0b533a2 - A bit of tracing about flattening (vor 7 Tagen)<Simon Peyton
 Jones>
 {{{


 --- /dev/null   2015-01-28 16:31:58.000000000 +0000
 +++ /tmp/ghctest-gSX4vv/test
 spaces/./boxy/Base1.run/Base1.comp.stderr.normalised     2016-09-30
 12:44:57.182659875 +0000
 @@ -0,0 +1,18 @@
 +
 +Base1.hs:20:13:
 +     Couldn't match type ‘a0 -> a0’ with ‘forall a. a -> a’
 +      Expected type: MEither Sid b
 +        Actual type: MEither (a0 -> a0) b
 +     In the expression: MLeft fid
 +      In an equation for ‘test1’: test1 fid = MLeft fid
 +
 +Base1.hs:25:39:
 +     Couldn't match type ‘a1 -> a1’ with ‘forall a. a -> a’
 +      Expected type: Maybe (Sid, Sid)
 +        Actual type: Maybe (a1 -> a1, a2 -> a2)
 +     In the expression: Just (x, y)
 +      In a case alternative: MRight y -> Just (x, y)
 +      In the expression:
 +        case m of {
 +          MRight y -> Just (x, y)
 +          _ -> Nothing }
 *** unexpected failure for Base1(normal)

 Compile failed (exit code 1) errors were:
 ghc-stage2: panic! (the 'impossible' happened)
   (GHC version 8.1.20160930 for x86_64-unknown-linux):
         ASSERT failed!
   m_aAI
   Call stack:
       CallStack (from HasCallStack):
         prettyCurrentCallStack, called at
 compiler/utils/Outputable.hs:1076:58 in ghc:Outputable
         callStackDoc, called at compiler/utils/Outputable.hs:1125:22 in
 ghc:Outputable
         assertPprPanic, called at compiler/typecheck/TcType.hs:979:47 in
 ghc:TcType
   Call stack:
       CallStack (from HasCallStack):
         prettyCurrentCallStack, called at
 compiler/utils/Outputable.hs:1076:58 in ghc:Outputable
         callStackDoc, called at compiler/utils/Outputable.hs:1080:37 in
 ghc:Outputable
         pprPanic, called at compiler/utils/Outputable.hs:1123:5 in
 ghc:Outputable
         assertPprPanic, called at compiler/typecheck/TcType.hs:979:47 in
 ghc:TcType

 Please report this as a GHC bug:
 https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.haskell.org%2Fghc%2Freportabug&data=01%7C01%7Csimonpj%40microsoft.com%7Cb15d11554ecf4f68173d08d3ee64ef42%7C72f988bf86f141af91ab2d7cd011db47%7C1&sdata=eG%2F4%2FH6lhGUFjL1my3GUE5Ho1hP3C4j0tkEihKvddyQ%3D&reserved=0


 *** unexpected failure for RaeBlogPost(normal)

 Compile failed (exit code 1) errors were:
 ghc-stage2: panic! (the 'impossible' happened)
   (GHC version 8.1.20160930 for x86_64-unknown-linux):
         ASSERT failed!
   m_awK
   Call stack:
       CallStack (from HasCallStack):
         prettyCurrentCallStack, called at
 compiler/utils/Outputable.hs:1076:58 in ghc:Outputable
         callStackDoc, called at compiler/utils/Outputable.hs:1125:22 in
 ghc:Outputable
         assertPprPanic, called at compiler/typecheck/TcType.hs:979:47 in
 ghc:TcType
   Call stack:
       CallStack (from HasCallStack):
         prettyCurrentCallStack, called at
 compiler/utils/Outputable.hs:1076:58 in ghc:Outputable
         callStackDoc, called at compiler/utils/Outputable.hs:1080:37 in
 ghc:Outputable
         pprPanic, called at compiler/utils/Outputable.hs:1123:5 in
 ghc:Outputable
         assertPprPanic, called at compiler/typecheck/TcType.hs:979:47 in
 ghc:TcType

 Please report this as a GHC bug:
 https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.haskell.org%2Fghc%2Freportabug&data=01%7C01%7Csimonpj%40microsoft.com%7Cb15d11554ecf4f68173d08d3ee64ef42%7C72f988bf86f141af91ab2d7cd011db47%7C1&sdata=eG%2F4%2FH6lhGUFjL1my3GUE5Ho1hP3C4j0tkEihKvddyQ%3D&reserved=0


 *** unexpected failure for TypeLevelVec(normal)
 }}}

 A subsequent commit by SPJ fixed the first one. It now compield without
 -DDEBUG again, but the other two failures (observable only with
 -DDEBUG) are still there.

 Since then, Travis has been reporting failures for the master branch. I
 only noticed now as I pushed something to master, and I got an email.
 Did you not get notifications about the breakage?

 If you did, was it unclear how to get to the log file?

 In any case: Simon, could you have a look and see if the ASSERT is
 pointing out a real bug introduced with your commits, or whether the
 ASSERT is wrong, so that we can build master with -DDEBUG again?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12682>
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