#3908: "Defined but not used" for variable used in Template Haskell splice
---------------------------------+------------------------------------------
Reporter: josh | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 6.12.1 | Keywords:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: Incorrect warning at
compile-time
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I encountered this warning on valid code using Template Haskell ; I had to
change "name" to "_name" to make it compile warning-free.
Test case:
{{{
{-# LANGUAGE FlexibleInstances, TemplateHaskell #-}
import Language.Haskell.TH
main :: IO ()
main = do
let name = mkName "name"
decl <- runQ [d| instance Show $(conT name) where show = undefined |]
print decl
}}}
Warnings:
{{{
TestCase.hs:6:8: Warning: Defined but not used: `name'
}}}
I found ticket #3873, but I don't know if it represents the same bug.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3908>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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