[GHC] #11460: OverloadedStrings cause error in annotation
GHC
ghc-devs at haskell.org
Tue Jan 19 11:52:03 UTC 2016
#11460: OverloadedStrings cause error in annotation
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Reporter: alanz | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 7.10.3
Keywords: | Operating System: Linux
Architecture: | Type of failure: GHC rejects
Unknown/Multiple | valid program
Test Case: | Blocked By:
Blocking: | Related Tickets:
Differential Rev(s): | Wiki Page:
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The following code
{{{#!hs
{-# LANGUAGE OverloadedStrings #-}
{-# ANN module "HLint: ignore Eta reduce" #-}
main = putStrLn "hello"
}}}
results in
{{{
/tmp/Foo.hs:3:1:
No instance for (Data.Data.Data a0) arising from an annotation
The type variable ‘a0’ is ambiguous
Note: there are several potential instances:
instance (Data.Data.Data a, Data.Data.Data b) =>
Data.Data.Data (Either a b)
-- Defined in ‘Data.Data’
instance Data.Data.Data t => Data.Data.Data (Data.Proxy.Proxy t)
-- Defined in ‘Data.Data’
instance (GHC.Types.Coercible a b, Data.Data.Data a,
Data.Data.Data b) =>
Data.Data.Data (Data.Type.Coercion.Coercion a b)
-- Defined in ‘Data.Data’
...plus 31 others
In the annotation: {-# ANN module "HLint: ignore Eta reduce" #-}
/tmp/Foo.hs:3:16:
No instance for (Data.String.IsString a0)
arising from the literal ‘"HLint: ignore Eta reduce"’
The type variable ‘a0’ is ambiguous
Note: there is a potential instance available:
instance Data.String.IsString [Char] -- Defined in ‘Data.String’
In the annotation: {-# ANN module "HLint: ignore Eta reduce" #-}
}}}
when using GHC 7.10.3, and similar for GHC 8 RC
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11460>
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