[GHC] #11540: ghc accepts non-standard type without language extension

[GHC]

#11540: ghc accepts non-standard type without language extension
-------------------------------------+-------------------------------------
        Reporter:  augustss          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.8.4
  (Parser)                           |
      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:                    |
-------------------------------------+-------------------------------------

Comment (by simonpj):

 Moreover, the current treatment (allowing nested contexts) is inconsistent
 with GADTs (#12087), which is undesirable.

 Nothing hard here; just gotta decide what we want and implement it.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11540#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler