[GHC] #12466: Typechecker regression: Inaccessible code in a type expected by the context

[GHC]

#12466: Typechecker regression: Inaccessible code in a type expected by the context
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.2.1
       Component:  Compiler (Type    |              Version:  8.1
  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 adamgundry):

 I agree that we should make the inaccessible code error into a warning.
 I'm on the fence as to whether that warning should automatically be
 suppressed in instance methods, or whether users should simply have to
 disable it themselves. It would be very useful for it automatically to be
 suppressed when checking generated code. See also #11066, #8128, #8740.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12466#comment:33>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler