#4173: Bad warning from quoted instance
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Reporter: igloo | Owner:
Type: bug | Status: new
Priority: normal | Milestone: 6.14.1
Component: Template Haskell | Version: 6.13
Keywords: | Difficulty:
Os: Unknown/Multiple | Testcase:
Architecture: Unknown/Multiple | Failure: None/Unknown
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This quoted instance gives a bogus warning; from #4127.
{{{
$ ghc -XTemplateHaskell
GHCi, version 6.13.20100704: http://www.haskell.org/ghc/ :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
Prelude> :m + Language.Haskell.TH
Prelude Language.Haskell.TH> runQ $ [d| f = undefined; class Foo x where {
f :: x -> x }; instance Foo Int where { f = id } |]
Loading package array-0.3.0.0 ... linking ... done.
Loading package containers-0.3.0.0 ... linking ... done.
Loading package pretty-1.0.1.1 ... linking ... done.
Loading package template-haskell ... linking ... done.
<interactive>:1:71:
Warning: No explicit method nor default method for `f'
In the instance declaration for `Foo Int'
In the Template Haskell quotation
[d| f = undefined
class Foo x where { f :: x -> x; }
instance Foo Int where
{ f = id } |]
In the second argument of `($)', namely
`[d| f = undefined
class Foo x where { f :: x -> x; }
instance Foo Int where
{ f = id } |]'
[ValD (VarP f) (NormalB (VarE GHC.Err.undefined)) [],ClassD [] Foo
[PlainTV x_0] [] [SigD f (AppT (AppT ArrowT (VarT x_0)) (VarT
x_0))],InstanceD [] (AppT (ConT Foo) (ConT GHC.Types.Int)) [ValD (VarP f)
(NormalB (VarE GHC.Base.id)) []]]
Prelude Language.Haskell.TH>
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4173>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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