[GHC] #10714: After implementing new installed package ID (hash of sdist), get rid of package keys

[GHC]

#10714: After implementing new installed package ID (hash of sdist), get rid of
package keys
-------------------------------------+-------------------------------------
        Reporter:  ezyang            |                Owner:  ezyang
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Package system    |              Version:  7.10.2
      Resolution:                    |             Keywords:  backpack
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
-------------------------------------+-------------------------------------

Comment (by Edward Z. Yang <ezyang@…>):

 In [changeset:"5b0191f74ab05b187f81ea037623338a615b1619/ghc"
 5b0191f7/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="5b0191f74ab05b187f81ea037623338a615b1619"
 Update Cabal to HEAD, IPID renamed to Component ID.

 This commit contains a Cabal submodule update which unifies installed
 package IDs and package keys under a single notion, a Component ID.
 We update GHC to keep follow this unification.  However, this commit
 does NOT rename installed package ID to component ID and package key to
 unit ID; the plan is to do that in a companion commit.

     - Compiler info now has "Requires unified installed package IDs"

     - 'exposed' is now expected to contain unit keys, not IPIDs.

     - Shadowing is no more.  We now just have a very simple strategy
       to deal with duplicate unit keys in combined package databases:
       if their ABIs are the same, use the latest one; otherwise error.
       Package databases maintain the invariant that there can only
       be one entry of a unit ID.

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

 Test Plan: validate

 Reviewers: simonpj, austin, bgamari, hvr, goldfire

 Subscribers: thomie

 Differential Revision: https://phabricator.haskell.org/D1184

 GHC Trac Issues: #10714
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10714#comment:4>
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