[GHC] #9122: Make Lint check for bad uses of `unsafeCoerce`

[GHC]

#9122: Make Lint check for bad uses of `unsafeCoerce`
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        Reporter:  simonpj           |                   Owner:  qnikst
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.8.2
      Resolution:                    |                Keywords:  newcomer
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:  Phab:D637
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Comment (by Austin Seipp <austin@…>):

 In [changeset:"76b1e11943d794da61d342c072a783862a9e2a1a/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="76b1e11943d794da61d342c072a783862a9e2a1a"
 Improve core linter so it catches unsafeCoerce problems (T9122)

 Summary:
 This is a draft of the patch that is sent for review.

 In this patch required changes in linter were introduced
 and actual check:

  - new helper function: primRepSizeB
  - primRep check for floating
  - Add access to dynamic flags in linter.
  - Implement additional lint rules.

 Reviewers: austin, goldfire, simonpj

 Reviewed By: simonpj

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D637

 GHC Trac Issues: #9122
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9122#comment:16>
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