cabal backpack bug

bug.cabal

-- Initial ignite.cabal generated by cabal init.  For further
-- documentation, see http://haskell.org/cabal/users-guide/

name:                bug
version:             0.1.0.0
-- synopsis:
-- description:
license:             BSD3
license-file:        LICENSE
author:              alexbiehl
maintainer:          alexbieh@...
-- copyright:
-- category:
build-type:          Simple
cabal-version:       >=2.0

library bug-sublib
  build-depends:      base, bug
  exposed-modules:    BugImpl
  reexported-modules: BugImpl as Bug
  default-language:   Haskell2010

library
  build-depends:       base >=4.10 && <4.11
  exposed-modules:     UsesBug
  signatures:          Bug
  default-language:    Haskell2010

executable bug-example
  build-depends:       base, bug-sublib
  default-language:    Haskell2010

Bug.hsig

signature Bug where

bug :: String

UsesBug.hs

module UsesBug where

import Bug

test = bug