[GHC] #10987: -i option requires named module

[GHC]

#10987: -i option requires named module
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        Reporter:  crockeea          |                Owner:  osa1
            Type:  bug               |               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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Changes (by osa1):

 * owner:   => osa1


Comment:

 Here's how this works:

 - When parsing a module, GHC assumes module name is Main if it's not
 given. (at
   least in GHCi. relevant code: HeaderInfo.getImports)

 - When a file or module name is passed, it first tries to disambiguate the
   string to see if it's a file path or module name. It does this by
 checking if
   <argument>.hs or <argument>.lhs exist. (relevant code: GHC.guessTarget)

 - If it's a file path, `GhcMake.summariseFile` is called. This one makes
 no
   assumptions one which module to look for. So this works fine. It doesn't
   check module name.

   In the example above, `ghci test/Bar` and `ghci Foo` run this function,
   because GHC finds `test/Bar.hs` and `Foo.hs` files.

 - If it's a module name(that is, GHC was unable to find `<argument>.hs`),
 then
   `GhcMake.summariseModule` is called. This one assumes that the module
 name is
   whatever's passed as argument, so it fails in the example above.

   `ghci -itest Bar` assumes module name should be `Bar`.
   `ghci Foo` would do the same, except it can find `Foo.hs` so it runs
   `summariseFile` which makes no assumptions on module name.

 One way to fix this is to never guess file names. `ghci Blah` would always
 look
 for a module named `Blah`, `ghci Blah.hs` would always look for a file,
 without
 any assumptions about which module it has.

 (To be continued...)

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10987#comment:1>
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