Re: [Haskell-cafe] GHCi fails to load C++ object files (missing symbol)
Hi Yves, It works (on Gentoo) when I compile it as a shared library. % g++ -o libstuff.so -fpic -shared Stuff.cpp % ghci Main.hs -L$PWD -lstuff GHCi, version 7.4.1: http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading object (dynamic) /h/argus/2/eng/haskell/cxx_stuff/libstuff.so ... done final link ... done Loading package filepath-1.3.0.0 ... linking ... done. Loading package bytestring-0.9.2.1 ... linking ... done. Loading package unix-2.5.1.0 ... linking ... done. Loading package old-locale-1.0.0.4 ... linking ... done. Loading package old-time-1.1.0.0 ... linking ... done. Loading package directory-1.1.0.2 ... linking ... done. Loading package process-1.1.0.1 ... linking ... done. Loading package goa-3.1 ... linking ... done. [1 of 1] Compiling Main ( Main.hs, interpreted ) Ok, modules loaded: Main. *Main GOA Hope this helps. Regards, Mark ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHCi fails to load C++ object files (missing symbol)
Thanks Mark! It works also here, and even without the -fpic flag. Was it necessary for you? 2012/3/8 Mark Wright markwri...@internode.on.net Hi Yves, It works (on Gentoo) when I compile it as a shared library. % g++ -o libstuff.so -fpic -shared Stuff.cpp % ghci Main.hs -L$PWD -lstuff GHCi, version 7.4.1: 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 object (dynamic) /h/argus/2/eng/haskell/cxx_stuff/libstuff.so ... done final link ... done Loading package filepath-1.3.0.0 ... linking ... done. Loading package bytestring-0.9.2.1 ... linking ... done. Loading package unix-2.5.1.0 ... linking ... done. Loading package old-locale-1.0.0.4 ... linking ... done. Loading package old-time-1.1.0.0 ... linking ... done. Loading package directory-1.1.0.2 ... linking ... done. Loading package process-1.1.0.1 ... linking ... done. Loading package goa-3.1 ... linking ... done. [1 of 1] Compiling Main ( Main.hs, interpreted ) Ok, modules loaded: Main. *Main GOA Hope this helps. Regards, Mark ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHCi fails to load C++ object files (missing symbol)
On Thu, 8 Mar 2012 12:55:51 +0100, Yves Parès yves.pa...@gmail.com wrote: Thanks Mark! It works also here, and even without the -fpic flag. Was it necessary for you? Hi Yves, Yes it is necessary for me to use -fpic when building C/C++ shared libraries as: - I'm on amd64 - Its a Gentoo developer policy to compile C/C++ shared libraries with -fPIC (same as -fpic on amd64) on amd64: http://devmanual.gentoo.org/archs/amd64/index.html Its normal to compile and link all the C/C++ with -fpic or -fPIC when building shared libraries. It might work without -fpic on x86 (32 bit): http://www.mail-archive.com/gentoo-dev@gentoo.org/msg01420.html 2) If it needs an -fPIC to compile on a non-x86 arch, it actually also needs -fPIC on x86 -- not to get the thing to compile correctly of course but for another reason: to avoid wasting memory when the code is used. Non-PIC library code on x86 wastes memory when used, even though it technically works. The dynamic loader is forced to create a private copy for each process using the non-PIC code, defeating one of the main reasons of using shared libraries in the first place -- to conserve RAM. Thanks, Mark ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] GHCi fails to load C++ object files (missing symbol)
On 8 Mar 2012, at 13:21, Mark Wright wrote: It might work without -fpic on x86 (32 bit): http://www.mail-archive.com/gentoo-dev@gentoo.org/msg01420.html On OS X, it is always on; I tried the example on 10.7, Xcode 4.3. I had to add ln -s /Applications/Xcode.app/Contents/Developer /Developer as ghc 7.0.4 looks for /Developer/usr/bin/gcc. For some funny reason ghc is at /usr/bin/ghc; since it is not a system distribution, it should be at /usr/local/bin/, which is also in the system path. On x86-64, there special relative addressing support, so there is no reason having it turned off, but some other good reasons for having on, like the security reason mentioned here: http://stackoverflow.com/questions/7078253/pic-on-osxs-gcc Hans ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
[Haskell-cafe] GHCi fails to load C++ object files (missing symbol)
Hi, I'm trying to have GHCi load a haskell file that depends on a C++
object file, which causes GHCi to fail because of an unknown symbol (*and I
did link with **libstdc++*), whereas the link into an executable with ghc
works and runs perfectly.
I've reduced my code to the smallest one that produces the problem:
The C++ part defines a mere class and C externals that enable communication
with Haskell:
// Header Stuff.hpp
class Base {
public:
Base();
~Base();
}
extern C {
Base* mkthing();
void delthing(Base*);
}
---
// Source Stuff.cpp
#include iostream
#include Stuff.hpp
using namespace std;
Base::Base()
{
cout Base created endl;
}
Base::~Base()
{
cout Base deleted endl;
}
extern C {
Base* mkthing()
{
return new Base();
}
void delthing(Base* b)
{
delete b;
}
}
Haskell code (just for reference, but I'm not sure it's relevant), Main.hs:
{-# LANGUAGE ForeignFunctionInterface #-}
import Foreign
import Foreign.C
foreign import ccall unsafe mkthing
mkthing :: IO (Ptr ())
foreign import ccall unsafe delthing
delthing :: Ptr () - IO ()
main = do
p - mkthing
delthing p
I then compile it with:
g++ -c Stuff.cpp
ghci Main.hs Stuff.o -lstdc++
And then the error is:
Loading object (static) Stuff.o ... done
Loading object (dynamic)
/usr/lib/i386-linux-gnu/gcc/i686-linux-gnu/4.5.2/libstdc++.so ... done
final link ... ghc: Stuff.o: unknown symbol `__dso_handle'
linking extra libraries/objects failed
Whereas 'ghc Main.hs Stuff.o -lstdc++' works just fine.
Does GHCi lacks a link directive that regular GHC has?
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Re: [Haskell-cafe] GHCi fails to load C++ object files (missing symbol)
Sorry for the double post, but I forgot to mention I'm using GHC 7.4 and
gcc/libstdc++ 4.5.2.
(Running Ubuntu 11.04 Natty Narwhal).
2012/3/7 Yves Parès yves.pa...@gmail.com
Hi, I'm trying to have GHCi load a haskell file that depends on a C++
object file, which causes GHCi to fail because of an unknown symbol (*and
I did link with **libstdc++*), whereas the link into an executable with
ghc works and runs perfectly.
I've reduced my code to the smallest one that produces the problem:
The C++ part defines a mere class and C externals that enable
communication with Haskell:
// Header Stuff.hpp
class Base {
public:
Base();
~Base();
}
extern C {
Base* mkthing();
void delthing(Base*);
}
---
// Source Stuff.cpp
#include iostream
#include Stuff.hpp
using namespace std;
Base::Base()
{
cout Base created endl;
}
Base::~Base()
{
cout Base deleted endl;
}
extern C {
Base* mkthing()
{
return new Base();
}
void delthing(Base* b)
{
delete b;
}
}
Haskell code (just for reference, but I'm not sure it's relevant), Main.hs:
{-# LANGUAGE ForeignFunctionInterface #-}
import Foreign
import Foreign.C
foreign import ccall unsafe mkthing
mkthing :: IO (Ptr ())
foreign import ccall unsafe delthing
delthing :: Ptr () - IO ()
main = do
p - mkthing
delthing p
I then compile it with:
g++ -c Stuff.cpp
ghci Main.hs Stuff.o -lstdc++
And then the error is:
Loading object (static) Stuff.o ... done
Loading object (dynamic)
/usr/lib/i386-linux-gnu/gcc/i686-linux-gnu/4.5.2/libstdc++.so ... done
final link ... ghc: Stuff.o: unknown symbol `__dso_handle'
linking extra libraries/objects failed
Whereas 'ghc Main.hs Stuff.o -lstdc++' works just fine.
Does GHCi lacks a link directive that regular GHC has?
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