[GHC] #15855: Warn about incomplete NamedFieldPuns patterns

[GHC]

#15855: Warn about incomplete NamedFieldPuns patterns
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        Reporter:  Artyom.Kazak      |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.1
      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:                    |
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Comment (by simonpj):

 Can you be more precise about what you are asking for?

 I think it might be something like:

 * Warn about any record pattern that does not provide a pattern for every
 field of the record.

 What about
 {{{
 g R{a,b} = a
 g R(a, ..} = a
 }}}
 Do those warn?

 Once we have a precise spec, I don't think this will be hard to implement
 (in the renamer).  I can offer advice.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15855#comment:2>
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