[GHC] #10502: Bad interaction of sandboxes and coverage

[GHC]

#10502: Bad interaction of sandboxes and coverage
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              Reporter:  qnikst      |             Owner:
                  Type:  bug         |            Status:  new
              Priority:  normal      |         Milestone:
             Component:  Code        |           Version:  7.10.1
  Coverage                           |  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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 It seems that when using sandboxes with project and coverage (`--enable-
 coverage`) cabal fails to generate and find .mix files for dependencies.

 Steps to reproduce:

 1. create shared sandbox (not sure that shared sandbox plays it's role
 here):
 {{{cabal sandbox init --sandbox=../.shared}}}
 2. install all dependencies with enable-coverage
 {{{cabal install --dependencies-only --enable-coverage --enable-tests}}}
 3. install library
 {{{cabal install --enable-coverage --run-tests}}}

 Expected results:

 1. Library will be built, coverage output will be generated.

 Actual results:
 hpc fails to find .mix files:

 {{{
 hpc: can not find
 netwo_Bdsn6Y1VKLa3MCczwSV70J/Network.Socket.ByteString.MsgHdr
 in ["./.hpc"
    ,"./dist/dist-sandbox-f7da581b/hpc/vanilla/mix/network-transport-
 tcp-0.4.1"
    ,"./dist/dist-sandbox-f7da581b/hpc/vanilla/mix/TestTCP"]
 }}}

 Tested on ghc-7.10.1 in clear official docker container on network-
 transport-tcp
 package.

 Side node: during tests on bigger project I have seen similar failures
 even on
 step 2 (e.g. network package fails with similar error message), but I was
 not
 able to reproduce it in minimal example.

 Possibly related report: #10259

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10502>
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