Re-exports can't be roots?

[tomjaguarpaw]

I'm confused by the behaviour of weeder around re-exports. For example

• B defines not_a_weed
• A imports B and re-exports not_a_weed
• A.not_a_weed is set as a root

Yet B.not_a_weed is detected as a weed. Is this expected behaviour? If so can I get the behaviour that I want? To put this in a more realistic context I want to use weeder on Opaleye by setting all functions in Opaleye (and a couple of other modules) to be roots.

This seems to be related to #40. In fact resolving that issue would probably solve my problem. But it seems that even without a feature to mark every export from a module as a root marking an individual re-export should mark its original definition as used.

--- weeder-example.cabal
cabal-version:      2.4
name:               weeder-example
version:            0.1.0.0

library
    exposed-modules:  A, B
    build-depends:    base
    hs-source-dirs:   src
    default-language: Haskell2010

--- cabal.project.local
package *
  ghc-options: -fwrite-ide-info

--- weeder.dhall
-- To run it:
-- ~/.ghcup/bin/cabal clean && ~/.ghcup/bin/cabal build  --with-ghc /opt/ghc/8.10.2/bin/ghc  all && ~/.cabal/bin/weeder-8.10

{ roots = [ "^B.not_a_weed$" ]
, type-class-roots = True }

--- src/A.hs
module A where

not_a_weed :: Int
not_a_weed = 1

--- src/B.hs
module B (not_a_weed) where

import A

% ~/.cabal/bin/weeder-8.10
src/A.hs:4:1: error: not_a_weed is unused

       2 ┃
       3 ┃ not_a_weed :: Int
       4 ┃ not_a_weed = 1

    Delete this definition or add ‘A.not_a_weed’ as a root to fix this error.


Weeds detected: 1