[GHC] #14152: Float exit paths out of recursive functions

[GHC]

#14152: Float exit paths out of recursive functions
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        Reporter:  nomeata           |                Owner:  (none)
            Type:  task              |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:  JoinPoints
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #14137 #10918     |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by nomeata):

 >  Ah! You probably need to topologically sort those abs_vars; see the
 `sortQuantVars` call in SetLevels.abstractVars. A bug waiting to happen.

 While sleeping over it, I was wondering: Did I really get that wrong? And
 I checked: No, I did not! The `abs_vars` are derived from `captured`, and
 that is always in dependency order by construction. So no need for
 `sortQuantVars`.

 So I reverted the (unnecessary and hence misleading) use of
 `sortQuantVars` in 270e3e9bbaabad3d9a1348cea9e46a9ecf1e5ec2, but left a
 comment that should prevent me from forgetting this again.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14152#comment:42>
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