[GHC] #14488: Can't define a lens for a field with a constraint

[GHC]

#14488: Can't define a lens for a field with a constraint
-------------------------------------+-------------------------------------
        Reporter:  int-index         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.0.2
  checker)                           |
      Resolution:                    |             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:                    |
-------------------------------------+-------------------------------------

Comment (by RyanGlScott):

 It looks like 3f5673f34a2f761423027bf46f64f7499708725f (`A collection of
 type-inference refactorings.`) fixed this.

 A regression test would be much appreciated!

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14488#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler