[GHC] #8883: FlexibleContexts checking should happen also on inferred signature

[GHC]

#8883: FlexibleContexts checking should happen also on inferred signature
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        Reporter:  Blaisorblade                 |            Owner:
            Type:  bug                          |  jstolarek
        Priority:  normal                       |           Status:  closed
       Component:  Compiler                     |        Milestone:
      Resolution:  fixed                        |          Version:  7.6.3
Operating System:  Unknown/Multiple             |         Keywords:
 Type of failure:  None/Unknown                 |     Architecture:
       Test Case:  typecheck/should_fail/T8883  |  Unknown/Multiple
        Blocking:                               |       Difficulty:
                                                |  Unknown
                                                |       Blocked By:
                                                |  Related Tickets:
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Comment (by simonpj):

 Lemming has a good point, I guess.  `Functor (PF a)` is currently rejected
 without `FlexibleContexts` but I guess it could instead be accepted.
 Moreover even in H98 the context `Functor (f a)` is accepted, so you could
 argue that with `TypeFamilies` we should accept `Functor (PF a)`.

 I can't get terribly excited about this decision; but I can see the logic,
 and I'll gladly change the current behaviour if there is support for doing
 so.  (This would affect both inferred and declared types, of course.)

 rwbarton: GHC does Haskell 2010 by default.  That's how we choose what to
 enable by default, otherwise we'd argue about "should X be on by default"
 for ages!

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8883#comment:17>
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