Might go a bit off topic but i have to bring this up since 9 out of 10 make tutorials on the internet do the same horrific mistake as you just did, 11 out of 10 code bases out in the wild as well. In your make file example the .o files are just depending on the .cpp files, not the header files they include, the header files those included header files include and the files they include etc etc. This means nothing wil…
.depend :
gcc -M *.c > .depend
then at the bottom:source .depend