[GHC] #14928: TH eats 50 GB memory when creating ADT with multiple constructors

[GHC]

#14928: TH eats 50 GB memory when creating ADT with multiple constructors
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        Reporter:  YitzGale          |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Template Haskell  |              Version:  8.2.2
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Compile-time      |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by YitzGale):

 @bgamari Thanks very much for that. Confirming your results: I retested
 using 8.4.3 and 8.6.0.20180714 from hvr's PPA. On 8.4.3 the bug reproduced
 with {{{-O1}}} but not with {{{-O0}}}. On 8.6.0.20180714 the bug did not
 reproduce at all, neither with {{{-O0}}} nor with {{{-O1}}}.

 And also thanks for your observations about the code generated by
 {{{mkMessages}}}. I'll report that as a separate issue.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14928#comment:7>
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