[GHC] #8692: when reporting missing modules, report them all at once

[GHC]

#8692: when reporting missing modules, report them all at once
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       Reporter:  Lemming           |             Owner:
           Type:  feature request   |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  Compiler          |           Version:  7.6.3
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 Currently, when a module is missing I get the message:
 {{{
 Main.hs:6:18:
     Could not find module `Data.StorableVector.Base'
     It is a member of the hidden package `storablevector-0.2.8'.
     Perhaps you need to add `storablevector' to the build-depends in your
 .cabal file.
     It is a member of the hidden package `storablevector-0.2.8.1'.
     Perhaps you need to add `storablevector' to the build-depends in your
 .cabal file.
     Use -v to see a list of the files searched for.
 }}}

 In order to solve the problem I add the package name to the Cabal file as
 suggested.
 However, if many modules are missing, then it becomes tedious to add every
 package individually and recompile with Cabal.
 It would be great if GHC shows _all_ missing modules and their according
 packages.
 This helps a lot when converting from the old Cabal style "recompile all
 library modules for an executable"
 to the new style "import the main library for every executable".

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8692>
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