[GHC] #12091: 'Variable not in scope" when using GHCi with `-fobject-code`

[GHC]

#12091: 'Variable not in scope" when using GHCi with `-fobject-code`
-------------------------------------+-------------------------------------
        Reporter:  thomie            |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  high              |            Milestone:
       Component:  GHCi              |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #7253, #14108     |  Differential Rev(s):  Phab:D3849
       Wiki Page:                    |
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Comment (by Ben Gamari <ben@…>):

 In [changeset:"ddb870bf7055ccc8ff8b86c161f31aad81d01add/ghc" ddb870b/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="ddb870bf7055ccc8ff8b86c161f31aad81d01add"
 Don't drop GHCi-defined functions with -fobject-code enabled

 The desugarer was using `targetRetainsAllBindings` as a litmus test for
 determining if a function was defined in interactive mode (and thus
 should be exported). However, there is a corner case where one can be in
 interactive mode and have `targetRetainsAllBindings` return `False`: if
 `-fobject-code` is enabled (since the target will no longer be
 `HscInteractive`). In such a scenario, we should fall back on a
 different test for determining if we are in a GHCi session. I chose to
 use `isInteractiveModule`, which appears to do the trick.

 Test Plan: make test TEST=T12091

 Reviewers: austin, bgamari

 Subscribers: rwbarton, thomie

 GHC Trac Issues: #12091

 Differential Revision: https://phabricator.haskell.org/D3849
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12091#comment:5>
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