[GHC] #15505: Assertion failures in tests T7224, T9201, LevPolyBounded

[GHC]

#15505: Assertion failures in tests T7224, T9201, LevPolyBounded
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        Reporter:  osa1              |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler (Type    |              Version:  8.5
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"43b08cfbac5ce7ad6fc245651329094896de06e0/ghc"
 43b08cfb/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="43b08cfbac5ce7ad6fc245651329094896de06e0"
 Add a solveEqualities to tcClassDecl1

 Trac #15505 showed that, when we have a type error, we
 could have an unfilled-in coercion hole.  We don't want an
 assertion error in that case.

 The underlying cause is that tcClassDecl1 should call
 solveEqualities to fully solve all top-level equalities
 (or fail in the attempt).

 I also refactored the ClassDecl case for tcTyClDecl1 into
 a new function tcClassDecl1.  That makes it symmetrical
 with the others.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15505#comment:4>
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