[GHC] #13464: Pattern match checker runs even when not needed

[GHC]

#13464: Pattern match checker runs even when not needed
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           Reporter:  jstolarek      |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 I have code that triggers pattern match checker warning:

 {{{
 Pattern match checker exceeded (2000000) iterations in
 a case alternative. (Use -fmax-pmcheck-iterations=n
 to set the maximun number of iterations to n)
 }}}

 I would like to silence that warning. Alas, `-Wno-incomplete-patterns`
 does nothing - the warning still appears. I would expect that if I do not
 want to check for incomplete patterns then pattern match checker is not
 run at all and thus does not exceed maximum number of iterations! I can
 only use `-w` to silence all the warnings but this is an overkill -
 definitely not what I want.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13464>
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