[GHC] #14648: ghc-pkg does handle unitids

[GHC]

#14648: ghc-pkg does handle unitids
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        Reporter:  lspitzner         |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  ghc-pkg           |              Version:  8.2.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by ezyang):

 Yes, the defaulting to pkgname-version is tiresome but it's this way for
 backwards compatibility (since that is how ghc-pkg worked in the old
 days); and the surprising behavior stems from another BC thing where
 version numbers parse with tags and then Cabal ignores the tag, so
 `semigroupoids-5.2.1-f552e489ce3109c2672606e2dc6e33c4f38174da930d5db0bb0dafbb4dccae8`
 parses into `semigroupoids-5.2.1` and off we go.

 If someone updates ghc-pkg not to use Cabal's "tag ignoring" parser and
 handles the parsing itself, we could make it error when it sees a tag, or
 better yet automatically interpret it as an IPID. It's more work in the
 implementation but it would smooth this edge.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14648#comment:3>
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