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Re: C++ shared library with pthread missing symbols
From: |
Ralf Wildenhues |
Subject: |
Re: C++ shared library with pthread missing symbols |
Date: |
Thu, 15 Dec 2005 08:22:48 +0100 |
User-agent: |
Mutt/1.5.11 |
Hi Simon,
* Simon Perreault wrote on Wed, Dec 14, 2005 at 05:01:53PM CET:
> Why does this create a library with missing symbols?
I believe pecause -nostdlib will cause gcc not to add -lpthread even if
-pthread is given. Could you file a bug with the GCC bugzilla (to
either fix the semantics or adjust the documentation)? Thanks.
It may not be trivial to work around within libtool. You can
probably LDFLAGS=-lpthread to work around in your special case.
> $ libtool --mode=link g++ -pthread -rpath /usr/local/lib testcase.lo -o
> libtestcase.la
> g++ -shared -nostdlib /usr/lib/gcc/i386-redhat-linux/4.1.0/../../../crti.o
> /usr/lib/gcc/i386-redhat-linux/4.1.0/crtbeginS.o .libs/testcase.o
> -L/usr/lib/gcc/i386-redhat-linux/4.1.0
> -L/usr/lib/gcc/i386-redhat-linux/4.1.0/../../.. -lstdc++ -lm -lc -lgcc_s
> /usr/lib/gcc/i386-redhat-linux/4.1.0/crtendS.o
> /usr/lib/gcc/i386-redhat-linux/4.1.0/../../../crtn.o -pthread -Wl,-soname
> -Wl,libtestcase.so.0 -o .libs/libtestcase.so.0.0.0
> (cd .libs && rm -f libtestcase.so.0 && ln -s libtestcase.so.0.0.0
> libtestcase.so.0)
> (cd .libs && rm -f libtestcase.so && ln -s libtestcase.so.0.0.0
> libtestcase.so)
> ar cru .libs/libtestcase.a testcase.o
> ranlib .libs/libtestcase.a
> creating libtestcase.la
> (cd .libs && rm -f libtestcase.la && ln -s ../libtestcase.la libtestcase.la)
>
> $ ldd -r .libs/libtestcase.so
> undefined symbol: pthread_create (.libs/libtestcase.so)
> linux-gate.so.1 => (0x00799000)
> libstdc++.so.6 => /usr/lib/libstdc++.so.6 (0x003a3000)
> libm.so.6 => /lib/libm.so.6 (0x00b89000)
> libc.so.6 => /lib/libc.so.6 (0x00cc7000)
> libgcc_s.so.1 => /lib/libgcc_s.so.1 (0x008b1000)
> /lib/ld-linux.so.2 (0x00531000)
>
> $ g++ --version
> g++ (GCC) 4.1.0 20051212 (Red Hat 4.1.0-0.7)
Cheers,
Ralf