#5398: Multiple declarations of uniquely generated name
---------------------------------+------------------------------------------
Reporter: basvandijk | Owner:
Type: bug | Status: new
Priority: normal | Component: Template Haskell
Version: 7.0.4 | Keywords:
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
---------------------------------+------------------------------------------
I originally [http://code.google.com/p/syb-with-class/issues/detail?id=4
reported] this problem in the `syb-with-class` bug tracker but I think
it's a bug in TH possibly related to #5362.
After increasing the version range of `template-haskell` in `syb-with-
class` to:
`template-haskell >= 2.4 && < 2.7`
the package fails to build on `ghc-7.2.1` with the following error:
{{{
$ cabal build --ghc-option=-ddump-splices
Preprocessing library syb-with-class-0.6.1.2...
Building syb-with-class-0.6.1.2...
[4 of 4] Compiling Data.Generics.SYB.WithClass.Instances (
Data/Generics/SYB/WithClass/Instances.hs,
dist/build/Data/Generics/SYB/WithClass/Instances.o )
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package array-0.3.0.3 ... linking ... done.
Loading package containers-0.4.1.0 ... linking ... done.
Loading package pretty-1.1.0.0 ... linking ... done.
Loading package template-haskell ... linking ... done.
Loading package bytestring-0.9.2.0 ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
Data/Generics/SYB/WithClass/Instances.hs:1:1: Splicing declarations
deriveTypeable ['DataType]
======>
Data/Generics/SYB/WithClass/Instances.hs:544:3-29
instance Typeable DataType where
{ typeOf _
= mkTyConApp
(mkTyCon "Data.Generics.SYB.WithClass.Basics.DataType")
ghc-prim:GHC.Types.[] }
Data/Generics/SYB/WithClass/Instances.hs:1:1: Splicing declarations
deriveData ['ByteString]
======>
Data/Generics/SYB/WithClass/Instances.hs:726:4-28
constr_a2Ya :: Constr
constr_a2Ya = mkConstr dataType_a2Y9 "PS" [] Prefix
dataType_a2Y9 :: DataType
dataType_a2Y9 = mkDataType "ByteString" [constr_a2Ya]
instance (Data ctx (ForeignPtr Word8),
Data ctx Int,
Sat (ctx ByteString),
Sat (ctx (ForeignPtr Word8)),
Sat (ctx Int)) =>
Data ctx ByteString where
{ gfoldl _ _f_a2Yb z_a2Yc x_a2Yd
= case x_a2Yd of {
Data.ByteString.Internal.PS arg_a2Ye arg_a2Yf arg_a2Yg
-> _f_a2Yb
(_f_a2Yb
(_f_a2Yb (z_a2Yc Data.ByteString.Internal.PS)
arg_a2Ye) arg_a2Yf)
arg_a2Yg }
gunfold _ _k_a2Yh z_a2Yi c_a2Yj
= case constrIndex c_a2Yj of {
1 -> _k_a2Yh
(_k_a2Yh (_k_a2Yh (z_a2Yi
Data.ByteString.Internal.PS)))
_ -> error "gunfold: fallthrough" }
toConstr _ x_a2Yk
= case x_a2Yk of {
Data.ByteString.Internal.PS _ _ _ -> constr_a2Ya }
dataTypeOf _ _ = dataType_a2Y9 }
Data/Generics/SYB/WithClass/Instances.hs:1:1: Splicing declarations
deriveData ['L.ByteString]
======>
Data/Generics/SYB/WithClass/Instances.hs:727:4-30
constr_a30f :: Constr
constr_a30f = mkConstr dataType_a30e "Empty" [] Prefix
constr_a30g :: Constr
constr_a30g = mkConstr dataType_a30e "Chunk" [] Prefix
dataType_a30e :: DataType
dataType_a30e = mkDataType "ByteString" [constr_a30f, constr_a30g]
instance (Data ctx ByteString,
Data ctx L.ByteString,
Sat (ctx L.ByteString),
Sat (ctx ByteString)) =>
Data ctx L.ByteString where
{ gfoldl _ _f_a30h z_a30i x_a30j
= case x_a30j of {
Data.ByteString.Lazy.Internal.Empty
-> z_a30i Data.ByteString.Lazy.Internal.Empty
Data.ByteString.Lazy.Internal.Chunk arg_a30k arg_a30l
-> _f_a30h
(_f_a30h (z_a30i
Data.ByteString.Lazy.Internal.Chunk) arg_a30k)
arg_a30l }
gunfold _ _k_a30m z_a30n c_a30o
= case constrIndex c_a30o of {
1 -> z_a30n Data.ByteString.Lazy.Internal.Empty
2 -> _k_a30m (_k_a30m (z_a30n
Data.ByteString.Lazy.Internal.Chunk))
_ -> error "gunfold: fallthrough" }
toConstr _ x_a30p
= case x_a30p of {
Data.ByteString.Lazy.Internal.Empty -> constr_a30f
Data.ByteString.Lazy.Internal.Chunk _ _ -> constr_a30g }
dataTypeOf _ _ = dataType_a30e }
Data/Generics/SYB/WithClass/Instances.hs:727:4:
Multiple declarations of `dataType'
Declared at: Data/Generics/SYB/WithClass/Instances.hs:726:4
Data/Generics/SYB/WithClass/Instances.hs:727:4
Data/Generics/SYB/WithClass/Instances.hs:727:4:
Multiple declarations of `constr'
Declared at: Data/Generics/SYB/WithClass/Instances.hs:726:4
Data/Generics/SYB/WithClass/Instances.hs:727:4
Data/Generics/SYB/WithClass/Instances.hs:727:4
}}}
The weird thing is that the generated names `dataType_a2Y9`,
`dataType_a30e`, `constr_a2Ya` and `constr_a30` are all unique.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5398>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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