[GHC] #12099: ghc --show-options lists invalid flags

[GHC]

#12099: ghc --show-options lists invalid flags
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        Reporter:  DanielG           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:  newcomer
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Other             |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Changes (by thomie):

 * keywords:   => newcomer


Comment:

 > all -fwarn flags are missing from flagsForCompletion

 That is intended behavior I think. Those flags are deprecated, ad replaced
 by equivalent `-W` flags.

 `-fwarn-`, `-fno-warn` and `-W` probably show up in the output of `--show-
 options` because of this code from `compiler/main/DynFlags.hs`:

 {{{
  ++ [ (NotDeprecated, unrecognisedWarning "W")
     , (NotDeprecated, unrecognisedWarning "fwarn-")
     , (NotDeprecated, unrecognisedWarning "fno-warn-") ]
 }}}

 For a newcomer. Adding a test is optional.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12099#comment:1>
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