[GHC] #8827: Inferring Safe mode with GeneralizedNewtypeDeriving is wrong

[GHC]

#8827: Inferring Safe mode with GeneralizedNewtypeDeriving is wrong
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        Reporter:  goldfire          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.9
      Resolution:                    |             Keywords:  SafeHaskell
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #8226, #8745      |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by dterei):

 I wrote up a detailed summary of all of this 6 months back here:
 [wiki:SafeRoles/RolesOverview Roles Overview]. I believe the recursive
 check can be done, and in such a way were we track that it's possible to
 import the right modules to satisfy the requirement that all constructors
 are in-scope, rather than actually require these imports (which is the
 main complaint against this check).

 The complications to this recursive check are internal vs. external
 modules and Safe Haskell import restrictions. They seem resolvable though,
 just annoying engineering most likely.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8827#comment:52>
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