[GHC] #11158: Combine exprIsTrivial and cpe_ExprIsTrivial

[GHC]

#11158: Combine exprIsTrivial and cpe_ExprIsTrivial
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        Reporter:  simonpj           |                Owner:
            Type:  task              |               Status:  infoneeded
        Priority:  highest           |            Milestone:  8.2.1
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1656
       Wiki Page:                    |
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Comment (by simonmar):

 I'll take a closer look later, but there seem to be multiple silly things
 going on.  This:

 {{{
 [section ""data" . sat_sNJ_closure" {
      sat_sNJ_closure:
          const ()_static_info;
  }]
 }}}

 Is **an instance of the () constructor** which is crazy because there only
 needs to be one instance of `()`, we don't need to create new instances of
 it.

 It's also totally silly for `Nothing` to be in an SRT.  Even when we're
 not optimising we ought to know that nullary constructors have
 `NoCafRefs`.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11158#comment:23>
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