Re: #16406: Array code works with GHC 8.4.4, hangs with GHC 8.6.4

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#16406: Array code works with GHC 8.4.4, hangs with GHC 8.6.4
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        Reporter:  arybczak          |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  libraries         |              Version:  8.6.4
  (other)                            |
      Resolution:                    |             Keywords:  array
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 osa1):

 Confirmed on GHC HEAD on Linux. It fails with `<<loop>>` exception when
 compiled.

 Some commits that may be relevant:

 - "Harden fixST" 5a49651f3161473b383ec497af38e9daa022b9ac
 - "Index arrays more eagerly" e7678d6a0607013749e9ba4d88df949ad1192765

 I think this is the commit that broke this example:

 - "Make accumArray and accum stricter"
 08345bd0e8d237ec3929aaee7613c4f76e07e131

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16406#comment:4>