I don't really understand (I've read but I'm not yet sure) how ccache works, so my question could be stupid, but I was wondering if during the debugging phase using it could be an issue instead of a help. I'll explain better: let's say that starting with a clean ccache I build an android ROM, the build goes fine and the ccache get populated. Then I boot up the ROM and I notice that something doesn't works as expected, I don't know, for the sake of the example let's say the WiFi doen't connect. I come back to my code and modify something that should fix it, but obviously I've to test it, so I build another time (using the ccache so the build doesn't take to much).
My question is, is possible that using the ccache for the subsequent build where I'm trying to fix my problem will make my modification worthless and so it's better to make a full clean build or that not influence at all the outcome?
The whole point of ccache is to support the workflow you described. Even doing a clean build will be incredibly fast as long as you don't clear your ccache cache.
Ccache is designed to cache compiler calls if they were already cached. But only then. On pretty much any modification the real compiler will be called.
Basically when you have ccache installed you don't need to know about it. It will just be faster.