#3779: dodgey warning about redundant class method imports
---------------------------------+------------------------------------------
Reporter: duncan | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 6.12.1
Keywords: | Difficulty:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: Incorrect warning at
compile-time
---------------------------------+------------------------------------------
Consider the code:
{{{
import qualified Distribution.Text as Text
( Text(disp, parse) )
instance Text.Text ReportLevel where
disp = ...
parse = ...
}}}
(This is from `Distribution/Client/BuildReports/Types.hs` in cabal-
install-0.8.0)
GHC warns us that:
{{{
Distribution/Client/BuildReports/Types.hs:17:0:
Warning: The import of `Text.disp, Text.parse'
from module `Distribution.Text' is redundant
}}}
But is it really redundant? If we change the import to:
{{{
import qualified Distribution.Text as Text
( Text )
}}}
Then the compile fails because `disp` and `parse` are not visible members
of the `Text` class.
Actually it's a bit odd that they become visible when imported qualified
when the instance decl itself must use non-qualified class method names.
But I guess that's just a quirk of H98.
One can get no warning by switching to:
{{{
import qualified Distribution.Text as Text
( Text(..) )
}}}
But that's not very satisfying. I did want to say which class methods I'm
using.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3779>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler_______________________________________________
Glasgow-haskell-bugs mailing list
[email protected]
http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs
