id,summary,reporter,owner,description,type,status,priority,milestone,component,version,resolution,keywords,cc,os,architecture,failure,difficulty,testcase,blockedby,blocking,related
3391,Generics compilation failure in combination with Data.Accessor deriving,darchon,simonpj,"When trying to compile (using my latest build: 6.11.20090722) a file with -XGenerics I get the following error:

{{{
""inplace/bin/ghc-stage2""  -O -H64m    -package-name clash-0.1 -hide-all-packages -i 
-ilibraries/clash-lib/cλash/. -ilibraries/clash-lib/cλash/dist-install/build 
-ilibraries/clash-lib/cλash/dist-install/build/autogen -Ilibraries/clash-lib/cλash/dist-install/build 
-Ilibraries/clash-lib/cλash/dist-install/build/autogen -Ilibraries/clash-lib/cλash/.   
-optP-include -optPlibraries/clash-lib/cλash/dist-install/build/autogen/cabal_macros.h 
-package base-4.1.0.0 -package containers-0.2.0.1 -package data-accessor-0.2.1 
-package data-accessor-template-0.2.1.1 -package filepath-1.1.0.1 -package ghc-6.11.20090722 
-package haskell98-1.0.1.0 -package pretty-1.0.1.0 -package prettyclass-1.0.0.0 -package syb-0.1.0.0 
-package template-haskell-2.4.0.0 -package transformers-0.1.4.0 -package vhdl-0.1   -O2 -XGenerics 
-fno-warn-deprecated-flags -Wwarn     -odir libraries/clash-lib/cλash/dist-install/build 
-hidir libraries/clash-lib/cλash/dist-install/build -stubdir libraries/clash-lib/cλash/dist-install/build 
-hisuf hi -osuf  o -hcsuf hc -c libraries/clash-lib/cλash/./CLasH/VHDL/VHDLTypes.hs 
-o libraries/clash-lib/cλash/dist-install/build/CLasH/VHDL/VHDLTypes.o

... Loading some packages etc etc. ...

/var/folders/wh/whtzeDfoGBCCu-65jmvmZU+++TI/-Tmp-/ghc58528_0/ghc58528_0.s:4565:0:
    FATAL:Symbol _clashzm0zi1_CLasHziVHDLziVHDLTypes_zdgfromVHDLState_closure already defined.
gmake[1]: *** [libraries/clash-lib/cλash/dist-install/build/CLasH/VHDL/VHDLTypes.o] Error 1
gmake: *** [all] Error 2
}}}

Indeed, when I compile with -dcore-lint I get to see this:
{{{
*** Core Lint Errors: in result of Desugar ***
<no location info>:
    Duplicate variables brought into scope
      [[CLasH.VHDL.VHDLTypes.$gfromTypeState,
        CLasH.VHDL.VHDLTypes.$gfromTypeState,
        CLasH.VHDL.VHDLTypes.$gfromTypeState],
       [CLasH.VHDL.VHDLTypes.$gtoTypeState,
        CLasH.VHDL.VHDLTypes.$gtoTypeState,
        CLasH.VHDL.VHDLTypes.$gtoTypeState],
       [CLasH.VHDL.VHDLTypes.$gfromEntity,
        CLasH.VHDL.VHDLTypes.$gfromEntity,
        CLasH.VHDL.VHDLTypes.$gfromEntity],
       [CLasH.VHDL.VHDLTypes.$gtoEntity, CLasH.VHDL.VHDLTypes.$gtoEntity,
        CLasH.VHDL.VHDLTypes.$gtoEntity],
       [CLasH.VHDL.VHDLTypes.$gfromOrdType,
        CLasH.VHDL.VHDLTypes.$gfromOrdType,
        CLasH.VHDL.VHDLTypes.$gfromOrdType],
       [CLasH.VHDL.VHDLTypes.$gtoOrdType,
        CLasH.VHDL.VHDLTypes.$gtoOrdType,
        CLasH.VHDL.VHDLTypes.$gtoOrdType],
       [CLasH.VHDL.VHDLTypes.$gfromHType,
        CLasH.VHDL.VHDLTypes.$gfromHType,
        CLasH.VHDL.VHDLTypes.$gfromHType],
       [CLasH.VHDL.VHDLTypes.$gtoHType, CLasH.VHDL.VHDLTypes.$gtoHType,
        CLasH.VHDL.VHDLTypes.$gtoHType],
       [CLasH.VHDL.VHDLTypes.$gfromVHDLState,
        CLasH.VHDL.VHDLTypes.$gfromVHDLState],
       [CLasH.VHDL.VHDLTypes.$gtoVHDLState,
        CLasH.VHDL.VHDLTypes.$gtoVHDLState]]
*** Offending Program ***

.. Many, Many lines of Core output ..

}}}

Note that when I compile without -XGenerics (but with -dcore-lint) I do not get any error.

I assume it has something to do with the following two lines in my sourcecode:
{{{
$( Data.Accessor.Template.deriveAccessors ''TypeState )
$( Data.Accessor.Template.deriveAccessors ''VHDLState )
}}}
As there are no errors when I remove those two TH splices (Sadly so, I need those accessors)

The implementation of Data.Accessor.Template.deriveAccessors can be found here (it's patched to work with version 2.4 of the template-haskell library): [http://github.com/christiaanb/data-accessor/blob/988137e3cb152ff0c66ec97919069d765b3669c6/template/src/Data/Accessor/Template.hs]

Maybe it's related to: #2456

For me it's not such a big problem as I will just compile that file with the NoGenerics Language pragma. But I would still like to know what might be causing this bug.

",bug,closed,normal,,Compiler,6.11,fixed,Generics,,Unknown/Multiple,Unknown/Multiple,,Unknown,typecheck/should_compile/T3391,,,