Object files not properly added to archive on mac

Question

I am trying to build an archive from a collection of object files. I am doing this with

ar -rs my_archive.a foo.o bar.o other_object_files.o.

On

Answer 1

The problem is that apparently common symbols are not added by default.

Option 1:

ar -rs my_archive.a foo.o bar.o other_object_files.o ranlib -c my_archive.a

Option 2:

libtool -c -static -o my_archive.a foo.o bar.o other_object_files.o