[GHC] #11361: Test tc253 doesn't pass with reversed uniques

6 Jan 2016

      #11361: Test tc253 doesn't pass with reversed uniques
-------------------------------------+-------------------------------------
           Reporter:  niteria        |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.1
  (Type checker)                     |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  GHC rejects
  Unknown/Multiple                   |  valid program
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 It fails with:

 {{{
 tc253.hs:23:7: error:
     • Couldn't match type ‘Maybe Int’ with ‘(String, Bool)’
       Expected type: Maybe Int -> (String, Int) -> Maybe Int
         Actual type: Fam Int Bool -> Fam Int Int -> Fam Int Bool
     • In the expression: inc (undefined :: Int)
       In an equation for ‘foo’: foo = inc (undefined :: Int)
 }}}

 Steps to reproduce:

 1. Add line
 `TEST_HC_OPTS += -dinitial-unique=16777000 -dunique-increment=-1`

 after line

 `TEST_HC_OPTS = -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output
 -no-user-$(GhcPackageDbFlag) -rtsopts $(EXTRA_HC_OPTS)`

 in `mk/test.mk`

 2. `make TESTS=tc253`

 I suspect this is related to #11148 since the symptoms are similar.

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11361
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