[GHC] #10635: -fwarn-redundant-constraints should not be part of -Wall

[GHC]

#10635: -fwarn-redundant-constraints should not be part of -Wall
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        Reporter:  Lemming           |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  7.11
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #9939, #9973,     |  Differential Rev(s):
  #10100, #10183, #11370             |
       Wiki Page:                    |
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Comment (by Lemming):

 Replying to [comment:29 svenpanne]:
 > Just a word of warning from a library maintainer's point of view:
 Including new flags into `-Wall` puts some non-trivial burden onto
 maintainers wanting a warning-free build. Simply adding a new pragma is
 not enough: Old GHCs don't know that pragma, so you have to put that into
 some ugly `#ifdef`s, which in turn oftern implies adding another
 (language) pragma to allow the preprocessor plus perhaps some changes in
 the `.cabal` file.

 I don't like CPP and would prefer that GHC gets a switch to disable
 warnings about certain pragmas.
 This was proposed in #2867. It should be possible to disable those
 warnings globally in the Cabal file.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10635#comment:30>
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