[GHC] #11580: panic on incompatible options

[GHC]

#11580: panic on incompatible options
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        Reporter:  dougm             |                Owner:
            Type:  bug               |               Status:  merge
        Priority:  low               |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.8.4
      Resolution:                    |             Keywords:  newcomer
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  Compile-time      |  (amd64)
  crash                              |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1925
       Wiki Page:                    |
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Comment (by rwbarton):

 For anyone else who was confused at first like me, the panic actually
 arises from specifying all ''three'' of `-XSafe`, `-XUnsafe` and
 `-XTrustworthy` because then the result of combining the first two flags
 is demanded when adding the third flag.

 We should still add

 * a test for `-XSafe -XUnsafe -XTrustworthy` (under `safeHaskell/flags`;
 I'm not going to do it right now just because I would have to build ghc to
 find out what the right error message is)

 * the original test in this ticket

 * possibly other versions of that test for the `-d`, `-f` and `-W` flags.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11580#comment:5>
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