Re: [Discuss-gnuradio] Out of Tree linker error... libgnuradio-MYMOD.so: undefined reference to `gr::fft::fft_complex::execute()'

[Tom Rondeau]

On Wed, Jul 23, 2014 at 4:24 PM, John Murphy <address@hidden> wrote:

I am getting a link error when making my Out-of-Tree module.

I apologize in advance for the length of this, my first post to this list. I get the daily 'digest' version.

This Out of Tree module was done with gr_modtool and cmake following the outline given in http://gnuradio.org/redmine/projects/gnuradio/wiki/OutOfTreeModules which, after some figuring out how my setup was missing some things, worked (make and install and runs in GRC) on another simpler block in this same module.

This is a re-run of the make spew that fails to link:

address@hidden build]$ make
Scanning dependencies of target gnuradio-comso
[  7%] Building CXX object lib/CMakeFiles/gnuradio-comso.dir/ofdm_rx_impl.cc.o
Linking CXX shared library libgnuradio-comso.so
[ 14%] Built target gnuradio-comso
Linking CXX executable test-comso
libgnuradio-comso.so: undefined reference to `gr::fft::fft_complex::execute()'
collect2: error: ld returned 1 exit status
make[2]: *** [lib/test-comso] Error 1
make[1]: *** [lib/CMakeFiles/test-comso.dir/all] Error 2
make: *** [all] Error 2
address@hidden build]$

Note - it seems to me this is saying it linked my custom code to the fft but failed to link the test code? Or am I mis-reading this?

In lib/CMakeLists.txt, look for the "include(GrTest)" line. Underneath a few lines there should be a "target_link_libraries." You need to make sure that this includes the proper libraries needed to build the executable. For your purposes, you probably need the fftw3f library as well.

Tom