[GHC] #10205: On Windows ghc-pkg always reports cache out of date

[GHC]

#10205: On Windows ghc-pkg always reports cache out of date
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        Reporter:  hgolden           |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  normal            |               Milestone:  7.10.2
       Component:  ghc-pkg           |                 Version:  7.10.1
      Resolution:                    |                Keywords:
Operating System:  Windows           |            Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
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Comment (by Kludgy):

 NTFS modified dates on Windows are unreliable, often clocking the
 directory modified date a few seconds ahead or behind their file changes.
 The results also vary depending on how NTFS is configured.

 It is likely that Windows users seeing this issue persist after a recache
 have millisecond precision enabled on timestamps, making ghc-pkg much more
 sensitive to the errors.

 Having ghc-pkg work on per-minute precision could help to ameliorate the
 problem, but ideally the tools should not be relying on implicit
 assumptions about directory modified times at all.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10205#comment:3>
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