“ld: unknown option: -soname” on OS X

Question

I try to build my app with CMake on Mac OS X, I get the following error:

Linking CXX shared library libsml.so
ld: unknown option: -soname
collect2: ld return         


        

Answer 1

You cleared you're problem, but I wanted to provide this a s a reference for future visitors because there's a bit more to creating a dynamic library on OS X. Also see Creating Dynamic Libraries in the Apple Developer pages.

OS X does not use the convention libcoolstuff.so.X.Y.Z. OS X uses the convention libcoolstuff.X.dylib. The, to embed X.Y.Z into the library, use -install_name, -current_version and -compatibility_version.

I don't know Cmake, but here's how it looks under Make. Your recipe to build the libcoolstuff 1.0.6 will look like:

libcoolstuff libcoolstuff.dylib:
    $(CC) $(CFLAGS) -dynamiclib -install_name "libcoolstuff.1.dylib" \
    -current_version 1.0.6 -compatibility_version 1.0 -o libcoolstuff.1.dylib $(OBJS)

And your make install rule would look like:

PREFIX?=/usr/local
LIBDIR?=$(PREFIX)/lib
...

install:
    cp -f libcoolstuff.1.dylib $(LIBDIR)/libcoolstuff.1.dylib
    rm -f $(LIBDIR)/libcoolstuff.dylib
    ln -s $(LIBDIR)/libcoolstuff.1.dylib $(LIBDIR)/libcoolstuff.dylib
    install_name_tool -change "libcoolstuff.1.dylib" "$(LIBDIR)/libcoolstuff.1.dylib" $(LIBDIR)/libcoolstuff.1.dylib

Under otool, it looks like:

$ otool -L libcoolstuff.dylib 
libcoolstuff.dylib:
    libcoolstuff.1.dylib (compatibility version 1.0.0, current version 1.0.6)
    /usr/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 111.1.7)

Finally, you would use it as expected:

export CFLAGS="-NDEBUG -g2 -O2 -Wall -arch ppc -arch ppc64"
make
...