PackageImports + Prelude edge case

Summary

Combining a PackageImports use of "base" and an explicit import from Prelude (which should disable the implicit import) fails to disable the implicit imports.

Steps to reproduce

{-# LANGUAGE PackageImports #-}

module Bug where

import           "base" Prelude (zip)

wobbly :: String
wobbly = "hello"

Expected behavior

The above should fail to compile because String is not in scope. A closer inspection (e.g. in ghci or with GHC.getNames) reveals that all the imports are in scope when only zip should be in scope.

Environment

• ghc 8.4.4
• ghc 8.6.5

Additional

This seems to be localised to the Prelude hiding. I also tried with the following

module NotBug where

import           "contravariant" Data.Functor.Contravariant.Divisible (Divisible)

wobble :: Divisible m => m ()
wobble = conquered

and it correctly fails to compile due to missing conquered.