[GHC] #15142: GHC HEAD regression: tcTyVarDetails

[GHC]

#15142: GHC HEAD regression: tcTyVarDetails
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  goldfire
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.6.1
       Component:  Compiler (Type    |              Version:  8.5
  checker)                           |             Keywords:  TypeInType,
      Resolution:                    |  TypeFamilies, CUSKs
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  crash or panic                     |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by goldfire):

 This goes back to the kind inference debate we had when working on #14066.
 The debate is memorialized
 [https://ghc.haskell.org/trac/ghc/wiki/GhcKinds/KindInference here],
 toward the top.

 Suppose we have

 {{{#!hs
 data Proxy (k :: Type) (a :: k) = Proxy  -- NB: CUSK
 }}}

 Do we accept

 {{{#!hs
 type ProxySym k a = Proxy k a
 data ProxyData k a = MkProxyData (Proxy k a)
 }}}

 Related are your thoughts on #14847

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15142#comment:11>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler