Incorrect unused-import warning in ghci

Try to load the following in ghci with -fwarn-unused-imports:

import Prelude hiding (zip)

zip :: [a] -> [b] -> [(a,b)]
zip _ _ = []

It spits out the usual warning for unused imports:

    Warning: The import of `Prelude' is redundant
               except perhaps to import instances from `Prelude'
             To import instances alone, use: import Prelude()

When compiled with ghc --make -fwarn-unused-imports no warning is printed. Also, the following does not generate a warning in ghci:

import Prelude hiding (zip)

zip :: [a] -> [b] -> [(a,b)]
zip _ _ = undefined

I expect ghci and ghc to agree on the warnings unless there's a good reason not to, and I do not expect warnings about declarations to depend on their implementation.

Trac metadata

Trac field	Value
Version	6.12.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture