[web-devel] GHCi runtime linker: fatal error: I found a duplicate definition for symbol (Yesod)

[Blake Rain]

I too had a the same problem with duplicate symbols from libHSghc, and
it seems to be a problem with yesod's dynamic server (or perhaps with
Hint).

My solution was first to remove the dependency on wai-handler-devel in
the yesod package by using the 'production' flag, like so:

$ cabal install yesod -fproduction

For running a dynamic server, the wai-handler-devel package installs an
executable called wai-handler-devel. You can use this rather than the
"runhaskell devel-server.hs" by providing the port, module and function
from your "devel-server.hs" file as arguments:

$ wai-handler-devel 3000 MySiteModule withMySite

The dynamic recompilation of wai-handler-devel is very useful, and I
hope this helps.

On Wed, 2011-03-23 at 14:22 -0400, Rick Richardson wrote:
> I removed all but network-2.2.1.0 and rebuilt everything, still no
> luck. But I'm sure you have set me on the right track, I will
> experiment with other permutations. 
> 
> 
> Thanks.
> 
> 
> 
> 
> On Wed, Mar 23, 2011 at 1:27 PM, Anton Cheshkov <acheshkov at gmail.com>
> wrote:
>         Hi Rick! I got the the same error day ago on my server.
>         Probably it happens because you have two network packages in
>         you system. 
>         
>         Try to compile all your packages  only on  network-2.2.1.10,
>         and delete package network-2.3 
>         
>         
>         Hope it helps you 
>         
>         
>         2011/3/23 Rick Richardson <rick.richardson at gmail.com>
>         
>                 
>                 
>                 I just installed the generic 7.0.2 binary on Ubuntu
>                  on both 32 bit and 64 bit machines.  Then I rm'd
>                   .ghc and .cabal  then fetched the current haskell
>                 platform. Built and installed.  
>                 
>                 
>                 After cabal installing all of the dependencies cabal
>                 said were required for yesod,  I run yesod.. the
>                 script creates the project. 
>                 
>                 
>                 When executing runhaskell devel-server.hs  I get this
>                 message 
>                 
>                 
>                 GHCi runtime linker: fatal error: I found a duplicate
>                 definition for symbol 
>                    ghczm7zi0zi2_AsmCodeGen_zdfMonadCmmOptM2_closure 
>                 whilst processing object file 
>                 
>                  /usr/local/lib/ghc-7.0.2/ghc-7.0.2/libHSghc-7.0.2.a 
>                 This could be caused by: 
>                    * Loading two different object files which export
>                 the same symbol 
>                    * Specifying the same object file twice on the GHCi
>                 command line 
>                    * An incorrect `package.conf' entry, causing some
>                 object to be 
>                      loaded twice. 
>                 GHCi cannot safely continue in this situation.
>                  Exiting now.  Sorry. 
>                 
>                 
>                 
>                 
>                 it's the same on both 32 and 64 bit.  
>                 
>                 
>                 Any ideas?   I am going to try to build 7.0.2 from
>                 source to see if that fixes it.  
>                 
>                 
>                 _______________________________________________
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>                 http://www.haskell.org/mailman/listinfo/web-devel
>                 
>         
>         
>         
>         -- 
>         Best regards,
>         Cheshkov Anton 
>         Phone: +7 909 005 18 82
>         Skype: cheshkov_anton
>         
> 
> 
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