[GHC] #12395: Misleading GHCi errors when package is installed

[GHC]

#12395: Misleading GHCi errors when package is installed
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        Reporter:  crockeea          |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:
       Component:  GHCi              |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #11536            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by crockeea):

 For the record, I was using a (common) sandbox for the library and the
 other program.

 In addition to cabal `new-build` and setting `expose: False`, another
 solution that should work would be to use `-hide-package mylib` when
 invoking GHCi. This results in a semi-reasonable error:
 {{{
 Failed to load interface for ‘<Deleted file>’
  It is a member of the hidden package ‘mylib-0.0.0.1’.
  Use -v to see a list of the files searched for.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12395#comment:6>
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