[GHC] #10560: -f and -O options interact in non-obvious, order dependent ways

[GHC]

#10560: -f and -O options interact in non-obvious, order dependent ways
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        Reporter:  bgamari           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by svenpanne):

 I think we should follow the principle of least surprise, and IMHO if the
 order is relevant, it *is* least surprising to all people who know various
 tools/compilers/etc.  I would strongly object any change regarding this,
 even adding warnings (will break builds, see above) or handling meta flags
 differently. If it helps, think of the command line as a list of functions
 modifying the flag state and GHC as doing a foldl over it, starting with
 its default state. :-)

 Making the documentation more explicit/clearer is perfectly fine, though.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10560#comment:9>
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