[GHC] #7697: (=>) works on non-constraints

[GHC]

#7697: (=>) works on non-constraints
----------------------------------------+-----------------------------------
Reporter:  monoidal                     |          Owner:                  
    Type:  bug                          |         Status:  new             
Priority:  normal                       |      Component:  Compiler        
 Version:  7.6.2                        |       Keywords:                  
      Os:  Unknown/Multiple             |   Architecture:  Unknown/Multiple
 Failure:  GHC accepts invalid program  |      Blockedby:                  
Blocking:                               |        Related:                  
----------------------------------------+-----------------------------------
 {{{
 f :: Int => Int
 f = id
 }}}

 compiles in 7.6 and HEAD. It shouldn't?

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7697>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler