[GHC] #1853: hpc mix files for Main modules overwrite each other

[GHC]

#1853: hpc mix files for Main modules overwrite each other
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        Reporter:  guest          |                Owner:
            Type:  bug            |               Status:  new
        Priority:  lowest         |            Milestone:  8.0.1
       Component:  Code Coverage  |              Version:  6.8.1
      Resolution:                 |             Keywords:
Operating System:  Linux          |         Architecture:  x86_64 (amd64)
 Type of failure:  None/Unknown   |            Test Case:
      Blocked By:                 |             Blocking:
 Related Tickets:                 |  Differential Rev(s):
       Wiki Page:                 |
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Comment (by ezyang):

 Hello all, I was recently looking at the Cabal code which is responsible
 for setting `hpcdir`, and I am a little confused by this ticket: why is it
 NOT sufficient to just specify different hpc directories for each main
 module? Does this have to do with wanting to combine tix files together?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/1853#comment:24>
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