[GHC] #10595: BuiltinRules override other rules in some cases.

[GHC]

#10595: BuiltinRules override other rules in some cases.
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        Reporter:  gjsimms           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:
       Component:  Compiler          |                 Version:  7.11
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Changes (by thomie):

 * status:  closed => new
 * resolution:  invalid =>


Comment:

 HEAD now shows the following warning for the example from the description:
 {{{
 Test.hs:4:11: warning:
     Rule "d exp" may never fire
       because rule "Class op exp" for ‘exp’ might fire first
     Probable fix: add phase [n] or [~n] to the competing rule
 }}}

 That "Probable fix" is not probable at all, because "Class op exp" is a
 built-in rule.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10595#comment:12>
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