[GHC] #8773: Require -XIncoherentInstances to write role annotations on class definitions

[GHC]

#8773: Require -XIncoherentInstances to write role annotations on class
definitions
--------------------------------------------+------------------------------
        Reporter:  goldfire                 |            Owner:  goldfire
            Type:  bug                      |           Status:  merge
        Priority:  normal                   |        Milestone:  7.8.1
       Component:  Compiler                 |          Version:  7.8.1-rc1
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  None/Unknown             |  Unknown/Multiple
       Test Case:  roles/should_fail/T8773  |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:  #8745
--------------------------------------------+------------------------------

Comment (by Austin Seipp <austin@…>):

 In [changeset:"a8a01e742434df11b830ab99af12d9045dfcbc4b/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="a8a01e742434df11b830ab99af12d9045dfcbc4b"
 Fix #8745 - GND is now -XSafe compatible.

 As discussed in the ticket, after the landing of #8773, GND is now
 -XSafe compatible.

 This fixes the test fallout as well. In particular SafeLang07 was
 removed following in the steps of SafeLang06, since it no longer failed
 from GND, but failed due to roles and was thus invalid.

 The other tests were tweaked to use TemplateHaskell instead of GND in
 order to trigger safety warnings.

 Signed-off-by: Austin Seipp <austin at well-typed.com>
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8773#comment:7>
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