[GHC] #12176: Failure of bidirectional type inference at the kind level

[GHC]

#12176: Failure of bidirectional type inference at the kind level
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        Reporter:  goldfire          |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:  TypeInType
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 Richard Eisenberg <rae@…>):

 In [changeset:"1696dbf4ad0fda4d7c5b4afe1911cab51d7dd0b0/ghc" 1696dbf/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="1696dbf4ad0fda4d7c5b4afe1911cab51d7dd0b0"
 Fix #12176 by being a bit more careful instantiating.

 Previously, looking up a TyCon that said "no" to mightBeUnsaturated
 would then instantiate all of its invisible binders. But this is
 wrong for vanilla type synonyms, whose RHS kind might legitimately
 start with invisible binders. So a little more care is taken now,
 only to instantiate those invisible binders that need to be (so that
 the TyCon isn't unsaturated).
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12176#comment:1>
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