[GHC] #7567: invalidateModSummaryCache throws exception if ms_hs_date is 0

[GHC]

#7567: invalidateModSummaryCache throws exception if ms_hs_date is 0
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        Reporter:  edsko             |                   Owner:
            Type:  bug               |  thoughtpolice
        Priority:  high              |                  Status:  infoneeded
       Component:  Compiler          |               Milestone:  7.12.1
      Resolution:                    |                 Version:  7.6.1
Operating System:  Unknown/Multiple  |                Keywords:
 Type of failure:  None/Unknown      |            Architecture:
      Blocked By:                    |  Unknown/Multiple
 Related Tickets:                    |               Test Case:
                                     |                Blocking:
                                     |  Differential Revisions:
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Changes (by thomie):

 * status:  new => infoneeded


Comment:

 Edsko: I am having trouble reproducing your issue.

 The file `main/GHC.hs` uses `Data.Time` from the `time` package, and has
 so from the beginning. `Time.toClockTime` is a function from the `old-
 time` package, which GHC doesn't use. How can it throw an error?

 Also if I call `addUTCTime (-1)` on `UTCTime (ModifiedJulianDay 0)
 (secondsToDiffTime 0)`, and force its result, nothing bad happens. Can you
 give me instructions how to trigger the bug. Thanks.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7567#comment:10>
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