#2681: Incorrect imported module not used warning
---------------------------------+------------------------------------------
Reporter: NeilMitchell | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.9 | Severity: normal
Keywords: | Testcase:
Architecture: Unknown/Multiple | Os: Unknown/Multiple
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A test case, with 3 files in.
{{{
-- AAA.hs
module AAA where
data Foo = Foo
-- AA.hs
module AA(Foo) where
import AAA
-- A.hs
module A where
import qualified AA
import AAA
type Bar = AA.Foo
}}}
Trying it out gives:
{{{
$ ghc --make
[3 of 3] Compiling A ( A.hs, A.o )
A.hs:2:0:
Warning: Module `AA' is imported, but nothing from it is used,
except perhaps instances visible in `AA'
To suppress this warning, use: import AA()
}}}
{{{Foo}}} comes from {{{AAA}}}, but is used with the import from {{{AA}}},
so it should be saying {{{AAA} is imported but not used. It seems the
import warnings are based on final fully resolved names, but this doesn't
deal with re-exports or qualification correctly.
I came accross this test case while tracking down a much more complex
example which gave a case where an unqualified module was reported as
being redundant - despite the fact that it was required - so it seems
there are several bugs around this area.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2681>
GHC <http://www.haskell.org/ghc/>
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