[GHC] #9955: ghc-stage1 compiles with bootstrapping ghc package, not the built one

[GHC]

#9955: ghc-stage1 compiles with bootstrapping ghc package, not the built one
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        Reporter:  ezyang            |                   Owner:
            Type:  bug               |                  Status:  patch
        Priority:  high              |               Milestone:  7.10.1
       Component:  Build System      |                 Version:  7.11
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:  Phab:D603
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Comment (by Edward Z. Yang <ezyang@…>):

 In [changeset:"1f1595195443700b7c2708fa903969fa2f0a927b/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="1f1595195443700b7c2708fa903969fa2f0a927b"
 Respect package visibility when deciding wired in packages.

 Summary:
 Previously, we would consider ALL versions of a wired-in package,
 no matter if they were exposed or not, and pick the latest version.
 This patch is a minor refinement on the behavior: now we try to
 pick the wired in package from just the list of exposed packages,
 and if there are no candidates fall back on the full list.  This
 means that if you do:

     -hide-all-packages -package wired-in-OLD-VERSION

 it will actually work by default (whereas previously you needed
 to *explicitly* -ignore-package the newer version).  This is especially
 useful for the 'ghc' package.  Fixes #9955.

 Signed-off-by: Edward Z. Yang <ezyang at cs.stanford.edu>

 Test Plan: validate

 Reviewers: simonpj, austin

 Reviewed By: austin

 Subscribers: carter, thomie

 Differential Revision: https://phabricator.haskell.org/D603

 GHC Trac Issues: #9955
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9955#comment:4>
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