[GHC] #11755: Seed unsafeGlobalDynFlags with enough information to use ppr

[GHC]

#11755: Seed unsafeGlobalDynFlags with enough information to use ppr
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           Reporter:  bgamari        |             Owner:  bgamari
               Type:  task           |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  7.10.3
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 At the moment the pretty-printer isn't functional if used before
 `DynFlags` is initialized by `initGhcMonad`. In particular things like
 `pprPanic` aren't usable since `unsafeGlobalDynFlags` isn't yet
 initialized. This is quite annoying during development.

 It seems like it should be possible to seed `unsafeGlobalDynFlags` with
 some minimal `DynFlags`, presumably with rather verbose output (as this is
 presumably what you want when debugging a compiler crash early in
 startup).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11755>
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