Package imports can cause linker errors

Summary

My project depends on servant-checked-exceptions and there is a similar package servant-checked-exceptions-core. Both export a similar module structure, and servant-checked-exceptions depends on servant-checked-exceptions-core through PackageImports. These interact in funny ways and can cause linker errors

Steps to reproduce

Please provide a set of concrete steps to reproduce the issue.

1. git clone https://github.com/arianvp/wire-servant-playground
2. cabal new-build
3. open the cabal file and change servant-checked-exceptions to servant-checked-exceptions-core.
4. cabal new-build
5. GHC will crash with a linker error
6. delete dist-newstyle
7. cabal new-build
8. GHC will report a type error

Expected behavior

GHC should have said:

src/Server.hs:9:12: error:
    • Couldn't match type ‘ServerT
                             (Throws NotFound
                              Servant.API.Sub.:> (Throws Unauthorized
                                                  Servant.API.Sub.:> Servant.API.Verbs.Get
                                                                       '[Servant.API.ContentTypes.JSON]
                                                                       String))
                             Handler’
                     with ‘m0 (Envelope es0 [Char])’
      Expected type: AsServer
                     Servant.API.Generic.:- (Servant.API.Capture.Capture "id" Int
                                             Servant.API.Sub.:> (Throws NotFound
                                                                 Servant.API.Sub.:> (Throws
                                                                                       Unauthorized
                                                                                     Servant.API.Sub.:> Servant.API.Verbs.Get
                                                                                                          '[Servant.API.ContentTypes.JSON]
                                                                                                          String)))
        Actual type: Int -> m0 (Envelope es0 [Char])
      The type variables ‘m0’, ‘es0’ are ambiguous
    • In the ‘_get’ field of a record
      In the expression:
        Routes
          {_get = const (pureSuccEnvelope "yo"), _put = const (return False)}
      In an equation for ‘server’:
          server
            = Routes
                {_get = const (pureSuccEnvelope "yo"), _put = const (return False)}
  |
9 |   { _get = const (pureSuccEnvelope "yo")

Actual behaviour

[nix-shell:~/Projects/wire/wire-servant-playground]$ cabal new-build 
Resolving dependencies...
Build profile: -w ghc-8.6.5 -O1
In order, the following will be built (use -v for more details):
 - wire-servant-playground-0.1.0.0 (lib) (configuration changed)
 - wire-servant-playground-0.1.0.0 (exe:wire-servant-playground) (configuration changed)
Configuring library for wire-servant-playground-0.1.0.0..
Preprocessing library for wire-servant-playground-0.1.0.0..
Building library for wire-servant-playground-0.1.0.0..
Configuring executable 'wire-servant-playground' for wire-servant-playground-0.1.0.0..
Preprocessing executable 'wire-servant-playground' for wire-servant-playground-0.1.0.0..
Building executable 'wire-servant-playground' for wire-servant-playground-0.1.0.0..
Linking /home/arian/Projects/wire/wire-servant-playground/dist-newstyle/build/x86_64-linux/ghc-8.6.5/wire-servant-playground-0.1.0.0/x/wire-servant-playground/build/wire-servant-playground/wire-servant-playground ...
/nix/store/0y7jmqnj48ikjh37n3dl9kqw9hnn68nq-binutils-2.31.1/bin/ld: /home/arian/Projects/wire/wire-servant-playground/dist-newstyle/build/x86_64-linux/ghc-8.6.5/wire-servant-playground-0.1.0.0/build/libHSwire-servant-playground-0.1.0.0-inplace.a(Server.o): in function `rCBH_info':
(.text+0xf53): undefined reference to `servantzmcheckedzmexceptionszm2zi2zi0zi0zm9015e86b13ae59e8ab1cda70195e06cc7212c2b8bb56605eb25da61824ed8275_ServantziCheckedziExceptionsziInternalziServantziServer_zdwzdcroute_info'
/nix/store/0y7jmqnj48ikjh37n3dl9kqw9hnn68nq-binutils-2.31.1/bin/ld: /home/arian/Projects/wire/wire-servant-playground/dist-newstyle/build/x86_64-linux/ghc-8.6.5/wire-servant-playground-0.1.0.0/build/libHSwire-servant-playground-0.1.0.0-inplace.a(Server.o): in function `uCPf_srt':
(.data+0x4d0): undefined reference to `servantzmcheckedzmexceptionszm2zi2zi0zi0zm9015e86b13ae59e8ab1cda70195e06cc7212c2b8bb56605eb25da61824ed8275_ServantziCheckedziExceptionsziInternalziServantziServer_zdwzdcroute_closure'
collect2: error: ld returned 1 exit status
`cc' failed in phase `Linker'. (Exit code: 1)

Environment

• GHC version used: 8.6.5

Optional:

• Operating System:
• System Architecture: