[GHC] #14323: Occurs check regressions in GHC 8.2.1 (and HEAD)

[GHC]

#14323: Occurs check regressions in GHC 8.2.1 (and HEAD)
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.2.1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 comment:8 done in
 {{{
 commit f20cf982f126aea968ed6a482551550ffb6650cf
 Author: Simon Peyton Jones <simonpj at microsoft.com>
 Date:   Mon Oct 9 13:16:59 2017 +0100

     Remove wc_insol from WantedConstraints

     This patch is a pure refactoring, which I've wanted to do for
     some time.  The main payload is

     * Remove the wc_insol field from WantedConstraints;
       instead put all the insolubles in wc_simple

     * Remove inert_insols from InertCans
       Instead put all the insolubles in inert_irreds

     * Add a cc_insol flag to CIrredCan, to record that
       the constraint is definitely insoluble

     Reasons

     * Quite a bit of code gets slightly simpler
     * Fewer concepts to keep separate
     * Insolubles don't happen at all in production code that is
       just being recompiled, so previously there was a lot of
       moving-about of empty sets

     A couple of error messages acutally improved.
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14323#comment:9>
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