[GHC] #8057: Warn when supplying version number to package-qualified import (was: PackageImports with versions for ghci)

[GHC]

#8057: Warn when supplying version number to package-qualified import
-------------------------------------+-------------------------------------
              Reporter:  Lemming     |            Owner:
                  Type:  feature     |           Status:  new
  request                            |        Milestone:
              Priority:  normal      |          Version:  7.6.3
             Component:  Compiler    |         Keywords:
            Resolution:              |     Architecture:  Unknown/Multiple
      Operating System:              |       Difficulty:  Unknown
  Unknown/Multiple                   |       Blocked By:
       Type of failure:              |  Related Tickets:
  None/Unknown                       |
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------
Changes (by thomie):

 * component:  GHCi => Compiler


Old description:

> Imports with explicit package names and versions would be nice to have in
> GHCi,
> because you cannot use the -package and -hide-package options from within
> GHCi.
> This is what currently happens:
> {{{
> $ ghci-7.6.3 -XPackageImports
> GHCi, version 7.6.3: http://www.haskell.org/ghc/  :? for help
> Loading package ghc-prim ... linking ... done.
> Loading package integer-gmp ... linking ... done.
> Loading package base ... linking ... done.
> Prelude> import Control.Monad.Trans.List
>
> <no location info>:
>     Ambiguous module name `Control.Monad.Trans.List':
>       it was found in multiple packages: transformers-0.3.0.0 List-0.5.1
> Prelude> import "transformers-0.3.0.0" Control.Monad.Trans.List
>
> <no location info>:
>     Could not find module `Control.Monad.Trans.List'
>     It is not a module in the current program, or in any known package.
> Prelude> :q
> Leaving GHCi.
> $ ghci-7.6.3 -hide-package List
> GHCi, version 7.6.3: http://www.haskell.org/ghc/  :? for help
> Loading package ghc-prim ... linking ... done.
> Loading package integer-gmp ... linking ... done.
> Loading package base ... linking ... done.
> Prelude> import Control.Monad.Trans.List
> Prelude Control.Monad.Trans.List>
> }}}
>
> However, I now see that the import with explicit package name works, if I
> omit the package version.
> I think GHCi should at least warn that providing a version does not work.
>
> See also #2362

New description:

 {{{
 $ ghci -XPackageImports
 GHCi, version 7.8.3: ...

 Prelude> import "transformers-0.3.0.0" Control.Monad.Trans.List

 <no location info>:
     Could not find module ‘Control.Monad.Trans.List’
     It is not a module in the current program, or in any known package.

 Prelude> import "transformers" Control.Monad.Trans.List
 Prelude Control.Monad.Trans.List>
 }}}

 The import with explicit package name works, if I omit the package
 version. I think GHC should at least warn that providing a version does
 not work.

 See also #2362.

--

Comment:

 Changed the description, because it's not a GHCi only problem.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8057#comment:1>
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