Link fails: ld: error: undefined symbol: term_simplify, because visibility is set to "hidden" during compilation #1

===>  Building for zimpl-3.6.2
[100% 1/1] : && /usr/local/libexec/ccache/cc -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing  -DNDEBUG -fstack-protector-strong src/CMakeFiles/zimpl.dir/zimpl/zimpl.c.o src/CMakeFiles/zimpl.dir/zimpl/xlpglue.c.o src/CMakeFiles/zimpl.dir/zimpl/zlpglue.c.o src/CMakeFiles/zimpl.dir/zimpl/ratlpstore.c.o src/CMakeFiles/zimpl.dir/zimpl/ratlpfwrite.c.o src/CMakeFiles/zimpl.dir/zimpl/ratmpswrite.c.o src/CMakeFiles/zimpl.dir/zimpl/ratmstwrite.c.o src/CMakeFiles/zimpl.dir/zimpl/ratordwrite.c.o src/CMakeFiles/zimpl.dir/zimpl/ratqbowrite.c.o src/CMakeFiles/zimpl.dir/zimpl/ratpresolve.c.o -o bin/zimpl  -Wl,-rpath,/usr/ports/math/zimpl/work/.build/lib:/usr/local/lib:  lib/libzimpl.so  /usr/local/lib/libgmp.so  /usr/local/lib/libgmpxx.so  /usr/lib/libz.so  /usr/lib/libm.so && :
FAILED: bin/zimpl 
: && /usr/local/libexec/ccache/cc -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing  -DNDEBUG -fstack-protector-strong src/CMakeFiles/zimpl.dir/zimpl/zimpl.c.o src/CMakeFiles/zimpl.dir/zimpl/xlpglue.c.o src/CMakeFiles/zimpl.dir/zimpl/zlpglue.c.o src/CMakeFiles/zimpl.dir/zimpl/ratlpstore.c.o src/CMakeFiles/zimpl.dir/zimpl/ratlpfwrite.c.o src/CMakeFiles/zimpl.dir/zimpl/ratmpswrite.c.o src/CMakeFiles/zimpl.dir/zimpl/ratmstwrite.c.o src/CMakeFiles/zimpl.dir/zimpl/ratordwrite.c.o src/CMakeFiles/zimpl.dir/zimpl/ratqbowrite.c.o src/CMakeFiles/zimpl.dir/zimpl/ratpresolve.c.o -o bin/zimpl  -Wl,-rpath,/usr/ports/math/zimpl/work/.build/lib:/usr/local/lib:  lib/libzimpl.so  /usr/local/lib/libgmp.so  /usr/local/lib/libgmpxx.so  /usr/lib/libz.so  /usr/lib/libm.so && :
ld: error: undefined symbol: term_simplify
>>> referenced by xlpglue.c
>>>               src/CMakeFiles/zimpl.dir/zimpl/xlpglue.c.o:(xlp_addcon_term)
>>> referenced by ratlpfwrite.c
>>>               src/CMakeFiles/zimpl.dir/zimpl/ratlpfwrite.c.o:(write_term)
>>> referenced by ratqbowrite.c
>>>               src/CMakeFiles/zimpl.dir/zimpl/ratqbowrite.c.o:(qbo_write)
>>> referenced 1 more times

ld: error: undefined symbol: numb_get_mpq
>>> referenced by xlpglue.c
>>>               src/CMakeFiles/zimpl.dir/zimpl/xlpglue.c.o:(xlp_addcon_term)
>>> referenced by xlpglue.c
>>>               src/CMakeFiles/zimpl.dir/zimpl/xlpglue.c.o:(xlp_addcon_term)
>>> referenced by xlpglue.c
>>>               src/CMakeFiles/zimpl.dir/zimpl/xlpglue.c.o:(xlp_addcon_term)
>>> referenced 13 more times

[ 62% 67/97] /usr/local/libexec/ccache/cc -DVERSION=\"3.6.2\" -Dlibzimpl_EXPORTS -I/usr/ports/math/zimpl/work/zimpl-362/src -I/usr/ports/math/zimpl/work/zimpl-362/src/zimpl -I/usr/ports/math/zimpl/work/.build/src -I/usr/local/include -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing -O2 -pipe  -fstack-protector-strong -fno-strict-aliasing  -DNDEBUG -std=gnu99 -fPIC -fvisibility=hidden -MD -MT src/CMakeFiles/libzimpl.dir/zimpl/mshell.c.o -MF src/CMakeFiles/libzimpl.dir/zimpl/mshell.c.o.d -o src/CMakeFiles/libzimpl.dir/zimpl/mshell.c.o -c /usr/ports/math/zimpl/work/zimpl-362/src/zimpl/mshell.c