[GHC] #10143: Separate PprFlags (used by Outputable) from DynFlags

[GHC]

#10143: Separate PprFlags (used by Outputable) from DynFlags
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              Reporter:  ezyang      |             Owner:  ezyang
                  Type:  task        |            Status:  new
              Priority:  normal      |         Milestone:
             Component:  Compiler    |           Version:  7.11
              Keywords:              |  Operating System:  Unknown/Multiple
          Architecture:              |   Type of failure:  None/Unknown
  Unknown/Multiple                   |        Blocked By:
             Test Case:              |   Related Tickets:
              Blocking:              |
Differential Revisions:              |
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 At the moment, SDoc computations have full access to the entirety of
 DynFlags, despite only a minusculely small amount of the data structure
 being relevant to them.  This proposal is to split out a `PprFlags`
 structure which will be contained in a `DynFlags`, and contain dynamic
 flags JUST for pretty-printing. There will be a function `pprFlags ::
 DynFlags -> PprFlags`. This also helps eliminate the circular dependency
 between `DynFlags` and `Outputable`.

 This structure is not complete, but it should give a sense for some of the
 things
 that need to be put in here:

 {{{

 data PprFlags = PprFlags {
   pprUserLength         :: Int,
   pprCols               :: Int,

   useUnicode      :: Bool,
   useUnicodeSyntax :: Bool,
   targetPlatform :: Platform,

   suppressUniques :: Bool,
   errorSpans :: Bool,
   suppressModulePrefixes :: Bool
     }
 }}}

 I have a patch in-progress which factors this out, but I want to get some
 sign-offs that this is a good refactoring before I finish it.

 Thanks!

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10143>
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