[GHC] #12822: Cleanup GHC verbosity flags

[GHC]

#12822: Cleanup GHC verbosity flags
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        Reporter:  hsyl20            |                Owner:  (none)
            Type:  task              |               Status:  new
        Priority:  low               |            Milestone:
       Component:  Compiler          |              Version:  8.0.1
      Resolution:                    |             Keywords:
                                     |  newcomer,flags
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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Comment (by bgamari):

 Let's first define specifically which flags we are talking about changing
 here; there are currently several broad categories that one might consider
 "verbosity" flags,

  * the dump (`-d*`) flags; these are currently handled uniformly within
 just and are represented by the `DynFlags.DumpFlags` type.
  * the `-fprint-*` flags
  * the `-fshow-options` flag
  * the `-v<n>` flags
  * the as-of-yet non-existent flags which denote the individual effects
 currently controlled by the `-v<n>` flags

 What concretely would you like to do with these flags? It's not entirely
 clear to me that, for instance, unifying the `-d*` flags with the
 `-fprint-*` flags is a good idea; afterall, the former are meant for
 developers while the latter are for users.


 Regarding the refactoring bit of (1): There should be no need to add a
 constructor to `DynFlags` (which is essentially just a product of all of
 the user-specified configuration GHC needs). You should have a look at how
 the `-On` flags are currently implemented; namely look at references to
 `optLevel` in `DynFlags`. Of particular interest will be
 `DynFlags.optLevelFlags`.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12822#comment:6>
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