How do developers fix bugs when compiling takes so long? It takes so long to compile Bitcoin Core on my machine... I can't imagine trying to fix bugs like a missed semicolon and having to wait an hour for the compiler to finish before testing. Is this really what devs have to deal with? Or is there a way to just compile smaller units of the code and run it quickly over and over again until all the semi colons are fixed?
Initial compiling of bitcoin-core can take a couple of minutes. If you have a multicore processor, you can use make -j&lt;cores+1&gt; to speed up compiling (parallel compiling).

Once bitcoin-core is compiled, a single semicolon change does (mostly) not require to recompile everything. You only compile the affected files (.cpp) again and do do the linking.

On most machines, compiling a simple change requires mostly less then 10 seconds.