[GHC] #2641: Revise the rules for -XExtendedDeafultRules

[GHC]

#2641: Revise the rules for -XExtendedDeafultRules
---------------------------------+------------------------------------------
    Reporter:  simonpj           |        Owner:                  
        Type:  feature request   |       Status:  new             
    Priority:  normal            |    Milestone:  6.12 branch     
   Component:  Compiler          |      Version:  6.8.3           
    Severity:  normal            |   Resolution:                  
    Keywords:                    |   Difficulty:  Unknown         
    Testcase:                    |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |  
---------------------------------+------------------------------------------
Changes (by simonpj):

  * summary:  Make -XExtendedDeafultRules a bit less liberal => Revise the
              rules for -XExtendedDeafultRules

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2641#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler