[GHC] #13868: Improved help suggested in the error message about "import".

[GHC]

#13868: Improved help suggested in the error message about "import".
-------------------------------------+-------------------------------------
           Reporter:  vanto          |             Owner:  (none)
               Type:  feature        |            Status:  new
  request                            |
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.2
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Poor/confusing
  Unknown/Multiple                   |  error message
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 I know that improving error messages is a headache in Haskell.
 But we still need to point out the mistakes or the nonsense.
 Here are some examples of import test "module" at the beginning of the
 program (any). I randomly chose the "Data" module. Below each import, the
 response from GHC. And below, my opinion.\\

 {{{
 import Data.Aaa
 Failed to load interface for `Data.Aaa'
 Perhaps you meant
   Data.Data (from base-4.9.1.0)
   Data.Map (from containers-0.5.7.1)
 }}}
 No relationship.\\

 {{{
 import Data.Bbb
 Failed to load interface for `Data.Bbb'
 }}}
 Ok.\\

 {{{
 import Data.Ccc
 Failed to load interface for `Data.Ccc'
 }}}
 Ok.\\

 {{{
 import Data.Ddd
 Failed to load interface for `Data.Ddd'
 Perhaps you meant Data.Ord (from base-4.9.1.0)
 }}}
 No relationship.\\

 {{{
 import Data.Eee
 Failed to load interface for `Data.Eee'
 Perhaps you meant
   Data.Eq (from base-4.9.1.0)
   Data.Set (from containers-0.5.7.1)
   Data.Tree (from containers-0.5.7.1)
 }}}
 No relationship.\\
 I stopped looking because I do not know how to correct it.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13868>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler