error on make

[rforcen]

cmake --version
cmake version 3.22.1

[ mkdir build; cd build; cmake .. ]

cmake ..
CMake Deprecation Warning at CMakeLists.txt:1 (cmake_minimum_required):
Compatibility with CMake < 2.8.12 will be removed from a future version of
CMake.

Update the VERSION argument value or use a ... suffix to tell
CMake that the project does not need compatibility with older versions.

-- The C compiler identification is GNU 11.4.0
-- The CXX compiler identification is GNU 11.4.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/asd/Downloads/cbor-cpp/build

asd@pop-os:~/Downloads/cbor-cpp/build$ make
[ 6%] Building CXX object CMakeFiles/cborcpp.dir/src/encoder.cpp.o
[ 13%] Building CXX object CMakeFiles/cborcpp.dir/src/decoder.cpp.o
[ 20%] Building CXX object CMakeFiles/cborcpp.dir/src/input.cpp.o
[ 26%] Building CXX object CMakeFiles/cborcpp.dir/src/listener_debug.cpp.o
[ 33%] Building CXX object CMakeFiles/cborcpp.dir/src/output_dynamic.cpp.o
[ 40%] Building CXX object CMakeFiles/cborcpp.dir/src/output_static.cpp.o
[ 46%] Linking CXX shared library libcborcpp.so
[ 46%] Built target cborcpp
[ 53%] Building CXX object CMakeFiles/testing.dir/src/encoder.cpp.o
[ 60%] Building CXX object CMakeFiles/testing.dir/src/decoder.cpp.o
[ 66%] Building CXX object CMakeFiles/testing.dir/src/input.cpp.o
[ 73%] Building CXX object CMakeFiles/testing.dir/src/listener_debug.cpp.o
[ 80%] Building CXX object CMakeFiles/testing.dir/src/output_dynamic.cpp.o
[ 86%] Building CXX object CMakeFiles/testing.dir/src/output_static.cpp.o
[ 93%] Building CXX object CMakeFiles/testing.dir/src/tests.cpp.o
/home/asd/Downloads/cbor-cpp/src/tests.cpp: In function ‘int main()’:
/home/asd/Downloads/cbor-cpp/src/tests.cpp:42:30: error: cannot declare variable ‘listener’ to be of abstract type ‘cbor::listener_debug’
42 | cbor::listener_debug listener;
| ^~~~~~~~
In file included from /home/asd/Downloads/cbor-cpp/src/cbor.h:26,
from /home/asd/Downloads/cbor-cpp/src/tests.cpp:19:
/home/asd/Downloads/cbor-cpp/src/listener_debug.h:25:11: note: because the following virtual functions are pure within ‘cbor::listener_debug’:
25 | class listener_debug : public listener {
| ^~~~~~~~~~~~~~
In file included from /home/asd/Downloads/cbor-cpp/src/decoder.h:21,
from /home/asd/Downloads/cbor-cpp/src/cbor.h:22,
from /home/asd/Downloads/cbor-cpp/src/tests.cpp:19:
/home/asd/Downloads/cbor-cpp/src/listener.h:27:22: note: ‘virtual void cbor::listener::on_float32(float)’
27 | virtual void on_float32(float value) = 0;
| ^~~~~~~~~~
/home/asd/Downloads/cbor-cpp/src/listener.h:28:22: note: ‘virtual void cbor::listener::on_double(double)’
28 | virtual void on_double(double value) = 0;
| ^~~~~~~~~
make[2]: *** [CMakeFiles/testing.dir/build.make:160: CMakeFiles/testing.dir/src/tests.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:111: CMakeFiles/testing.dir/all] Error 2
make: *** [Makefile:91: all] Error 2

[Reckan]

I had a very similar issue. I fixed mine by adding:
virtual void on_float32(float value);
virtual void on_double(double value);
to listener_debug.h and defining them in the .cpp file.
I'm not sure if this was the best solution, though.