Warning: The import of `B.foo' from module `A' is redundant

Let's consider such A.hs:

module A (C(foo)) where

class C a where
    foo :: a
    foo = bar
    bar :: a
    bar = foo

and B.hs:

module B (Foo(..)) where

import qualified A as B (C(foo))
-- import qualified A as B (C) -- ? erros too

data Foo = Foo Int deriving Show


instance B.C Foo where
    foo = Foo 4

Trying to build:

$ ghc --make -Wall -Werror B
[1 of 2] Compiling A                ( A.hs, A.o )
[2 of 2] Compiling B                ( B.hs, B.o )

B.hs:3:0:
    Warning: The import of `B.foo' from module `A' is redundant

<no location info>: 
Failing due to -Werror.

If I will remove foo somehow - I will get another error. At least message looks misleading, and warning seems to be false positive.

Might be related ot #1074 (closed)

Trac metadata

Trac field	Value
Version	6.12.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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