Warnings even with -w specified

Sorry for the long test case, but my attempt at reducing it caused the bug to disappear!

C:\Documents\Uni>darcs get http://www.cs.york.ac.uk/fp/darcs/derive
Directory 'C:/Documents/Uni/derive' already exists, creating repository as 'C:/D
ocuments/Uni/derive_0'
Copying patch 349 of 349... done!
Applying patch 349 of 349... done.
Finished getting.

C:\Documents\Uni>cd derive_0

C:\Documents\Uni\derive_0>runhaskell Setup configure
Configuring derive-0.1...

C:\Documents\Uni\derive_0>runhaskell Setup build
Preprocessing library derive-0.1...
Preprocessing executables for derive-0.1...
Building derive-0.1...
[ 1 of 40] Compiling Language.Haskell.TH.SYB ( Language/Haskell/TH/SYB.hs, dist\
build/Language/Haskell/TH/SYB.o )
[ 2 of 40] Compiling Language.Haskell.TH.FixedPpr ( Language/Haskell/TH/FixedPpr
.hs, dist\build/Language/Haskell/TH/FixedPpr.o )
[ 3 of 40] Compiling Language.Haskell.TH.Data ( Language/Haskell/TH/Data.hs, dis
t\build/Language/Haskell/TH/Data.o )
[ 4 of 40] Compiling Language.Haskell.TH.Helper ( Language/Haskell/TH/Helper.hs,
 dist\build/Language/Haskell/TH/Helper.o )
[ 5 of 40] Compiling Language.Haskell.TH.Peephole ( Language/Haskell/TH/Peephole
.hs, dist\build/Language/Haskell/TH/Peephole.o )
[ 6 of 40] Compiling Language.Haskell.TH.All ( Language/Haskell/TH/All.hs, dist\
build/Language/Haskell/TH/All.o )

Language/Haskell/TH/All.hs:8:4:
    Warning: The export item `module Language.Haskell.TH.SYB' exports nothing
[ 7 of 40] Compiling Data.Derive.Uniplate ( Data/Derive/Uniplate.hs, dist\build/
Data/Derive/Uniplate.o )
[ 8 of 40] Compiling Data.Derive.Typeable ( Data/Derive/Typeable.hs, dist\build/
Data/Derive/Typeable.o )
[ 9 of 40] Compiling Data.Derive.TTypeable ( Data/Derive/TTypeable.hs, dist\buil
d/Data/Derive/TTypeable.o )
[10 of 40] Compiling Data.Derive.Show ( Data/Derive/Show.hs, dist\build/Data/Der
ive/Show.o )
[11 of 40] Compiling Data.Derive.Set  ( Data/Derive/Set.hs, dist\build/Data/Deri
ve/Set.o )
[12 of 40] Compiling Data.Derive.Serial ( Data/Derive/Serial.hs, dist\build/Data
/Derive/Serial.o )

C:\Documents\Uni\derive_0>head Language\Haskell\TH\All.hs
{-# OPTIONS_GHC -w #-}

module Language.Haskell.TH.All (
    module Language.Haskell.TH.All,
    module Language.Haskell.TH.Syntax, module Language.Haskell.TH.Peephole,
    module Language.Haskell.TH.Helper, module Language.Haskell.TH.FixedPpr,
    module Language.Haskell.TH.Data,
    module Language.Haskell.TH.SYB
    ) where

i.e. using the Derive darcs version, there is a warning being raised for Language.Haskell.TH.All even though -w is being specified. In the module Language.Haskell.TH.SYB (which is indeed empty after CPP'ing) an identical error is raised, which can be removed with -fno-warn-unused-imports.

Trac metadata

Trac field	Value
Version	6.8.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture	Unknown