This Makefile will build an example AppImage for testing purpose. First you need to build a version of GCC that is newer than the default one on your system and install it to a custom prefix, let's say $HOME/gcc.

Then run make with the GCC_PREFIX variable set to that path:

GCC_PREFIX="$HOME/gcc" make

Now run CHECKRT_DEBUG=1 ./example-1-x86_64.AppImage. The output should look similar to this:

$ CHECKRT_DEBUG=1 ./example-1-x86_64.AppImage
[DEBUG] get_exe_dir: exe directory found at: /tmp/.mount_examplFaIgjO/checkrt
[DEBUG] symbol_version: searching bundled library: /tmp/.mount_examplFaIgjO/checkrt/gcc/libgcc_s.so.1
[DEBUG] symbol_version: symbol GCC_14.0.0 found
[DEBUG] get_system_library_path: libgcc_s.so.1 resolved to: /lib/x86_64-linux-gnu/libgcc_s.so.1
[DEBUG] symbol_version: searching system library: /lib/x86_64-linux-gnu/libgcc_s.so.1
[DEBUG] symbol_version: symbol GCC_14.0.0 found
[DEBUG] use_bundled_library: use SYSTEM libgcc_s.so.1 library
[DEBUG] symbol_version: searching bundled library: /tmp/.mount_examplFaIgjO/checkrt/cxx/libstdc++.so.6
[DEBUG] symbol_version: symbol GLIBCXX_3.4.34 found
[DEBUG] get_system_library_path: libstdc++.so.6 resolved to: /lib/x86_64-linux-gnu/libstdc++.so.6
[DEBUG] symbol_version: searching system library: /lib/x86_64-linux-gnu/libstdc++.so.6
[DEBUG] symbol_version: symbol GLIBCXX_3.4.33 found
[DEBUG] use_bundled_library: use BUNDLED libstdc++.so.6 library
[DEBUG] LD_LIBRARY_PATH=/tmp/.mount_examplFaIgjO/checkrt/cxx:
[DEBUG] LD_PRELOAD=/tmp/.mount_examplFaIgjO/checkrt/exec.so:
hello world