[GHC] #13495: ghc-stage1: panic! (the 'impossible' happened) creating cross compiler for PPC

[GHC]

#13495: ghc-stage1: panic! (the 'impossible' happened) creating cross compiler for
PPC
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        Reporter:  jms                  |                Owner:  (none)
            Type:  bug                  |               Status:  new
        Priority:  normal               |            Milestone:  8.2.1
       Component:  Compiler             |              Version:  8.0.2
      Resolution:                       |             Keywords:
Operating System:  Linux                |         Architecture:  powerpc
 Type of failure:  Building GHC failed  |            Test Case:
      Blocked By:                       |             Blocking:
 Related Tickets:                       |  Differential Rev(s):
       Wiki Page:                       |
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Comment (by rwbarton):

 Let's keep this open as it pointed out that GHC fails to ignore `-fllvm`
 in an unregisterized compiler.

 I don't have time to fix this right now but it looks like we just need to
 check for `HscLlvm` as well in this snippet near the end of `DynFlags`:
 {{{#!hs
  | hscTarget dflags == HscAsm &&
    platformUnregisterised (targetPlatform dflags)
     = loop (dflags { hscTarget = HscC })
            "Compiler unregisterised, so compiling via C"
 }}}

 (Maybe it would even be better to merge the targets `HscAsm` and
 `HscLlvm`, since they are equivalent for most purposes besides actually
 building the build pipeline?)

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13495#comment:5>
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