[GHC] #11025: Per-database shadowing

[GHC]

#11025: Per-database shadowing
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        Reporter:  ezyang            |                Owner:  ezyang
            Type:  bug               |               Status:  closed
        Priority:  high              |            Milestone:  8.0.1
       Component:  Package system    |              Version:  7.11
      Resolution:  fixed             |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:  cabal/shadow
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1385
       Wiki Page:                    |
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Changes (by thomie):

 * testcase:   => cabal/shadow
 * status:  new => closed
 * resolution:   => fixed


Comment:

 In commit 39b71e81ec1044518f065d0055676d713521e483:
 {{{
 Author: Edward Z. Yang <ezyang at cs.stanford.edu>
 Date:   Tue Oct 27 14:47:33 2015 -0700

     Reimplement shadowing on a per database basis.

     Summary:
     This commit reimplements shadowing on package databases by doing
     the shadowing calculation on a per-database basis: specifically,
     if a later package database shadows a package from the earlier
     databases, we first remove that package (and its transitive
     dependencies) before merging the databases together.

     This should also fix bootstrapping GHC HEAD with HEAD.

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

     Test Plan: validate

     Reviewers: ggreif, bgamari, austin

     Subscribers: thomie

     Differential Revision: https://phabricator.haskell.org/D1385
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11025#comment:2>
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