[GHC] #15810: Kind inference error in classes

[GHC]

#15810: Kind inference error in classes
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        Reporter:  goldfire          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.1
      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 RyanGlScott):

 That change does indeed appear to fix the issue when I tried it. Only one
 test case seems to regress with this change:

 {{{#!diff
 diff -uw "polykinds/T7328.run/T7328.stderr.normalised"
 "polykinds/T7328.run/T7328.comp.stderr.normalised"
 --- polykinds/T7328.run/T7328.stderr.normalised 2018-11-11
 15:15:40.843707612 -0500
 +++ polykinds/T7328.run/T7328.comp.stderr.normalised    2018-11-11
 15:15:40.843707612 -0500
 @@ -1,6 +1,6 @@

  T7328.hs:8:34:
 -     Occurs check: cannot construct the infinite kind: k1 ~ k0 -> k1
 +     Occurs check: cannot construct the infinite kind: k00 ~ k0 -> k00
       In the first argument of ‘Foo’, namely ‘f’
        In the first argument of ‘Proxy’, namely ‘(Foo f)’
        In the type signature: foo :: a ~ f i => Proxy (Foo f)
 }}}

 I can't tell if this is expected behavior or not.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15810#comment:1>
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