[GHC] #10653: PatternSynonyms should be imported/exported as part of the wildcard notation

[GHC]

#10653: PatternSynonyms should be imported/exported as part of the wildcard
notation
-------------------------------------+-------------------------------------
        Reporter:  gridaphobe        |                   Owner:
            Type:  feature request   |                  Status:  new
        Priority:  normal            |               Milestone:  7.12.1
       Component:  Compiler          |                 Version:  7.11
      Resolution:                    |                Keywords:  pattern
                                     |  synonyms
Operating System:  Unknown/Multiple  |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by gridaphobe):

 Replying to [comment:5 goldfire]:
 > > > If `Q` belongs to pairs, then is it ever imported with `(..)`
 attached to some type? I would guess "no".
 > >
 > > Well I suppose it would be possible, since
 > >
 > > {{{
 > > import GHC.Tuple ((,)(..))
 > > }}}
 > >
 > > is a valid import declaration.
 >
 > Yes, but no pattern synonyms are defined in `GHC.Tuple`.

 Right, you would need a module that re-exported `(,)` in addition to a
 pattern synonym, e.g.

 {{{
 module A ( (,)(..), pattern Q )
 }}}

 so it's very unlikely to happen in practice. But, if you are re-exporting
 `(,)` from your module, I think it would be reasonable to attach the
 pattern synonyms that belong to `(,)`. I see this as module `A` providing
 its own view of pairs.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10653#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler