[GHC] #11071: "Not in scope" errors should be more informative for qualified names.

[GHC]

#11071: "Not in scope" errors should be more informative for qualified names.
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        Reporter:  mojojojo          |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.10.2
      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 simonpj):

 I think comment:5 has it right.  Adding supplementary hints to a failed
 use of a qualified name would be a fine thing to do.  Not entirely trivial
 to implement: the `GlobalRdrEnv` records what ''is'' in scope, not what is
 ''not'' in scope.  So you'd have to go back to the original imports.

 Quite do-able though.

 Simon

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11071#comment:6>
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