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

[John Murphy]

> From: Marcus M?ller <address@hidden>
> you use gr-fft in your code, but then don't tell your linker to link
> against that, which leaves your libgnuradio-comso missing the symbols
> from gr::fft, which breaks linking test-comso.
> So what you need to do is edit your CMakeLists.txt in your module's root
> dir and replace
> set(GR_REQUIRED_COMPONENTS RUNTIME)
> by
> set(GR_REQUIRED_COMPONENTS RUNTIME FFT)
> which will add the necessary linker directives, usually.
> Then you will need to add
>     ${GNURADIO_FFT_LIBRARY_DIRS}
> to your
> link_directories(...)
> further down.
> now, in your lib/ directory, edit the CMakeLists.txt
> and extend the  target_link_libraries(<yourmodule>...) directive with
>     ${GNURADIO_FFT_LIBRARIES}
> and do the same for the test-<yourmodule> target_link_libraries.

Needed to say a "Thanks Marcus" for this very complete answer. Saw this come 
thru the digest after I re-read where it indicates (some of) this in the wiki.
It seems to build without the GNURADIO_FFT_LIBRARY_DIRS or the 
GNURADIO_FFT_LIBRARIES entries, which I did not notice being indicated in the 
wiki page, unless somehow cmake already does that when you add the FFT part (I 
should probably go look at what is in those files now)? But if I run into 
trouble at runtime I will be sure to come back to try this.