Without a defined path the XDG_CACHE_HOME is used.
But some users set XDG_CACHE_HOME to a path in tmpfs for a clean system between reboots and to enlarge their SSD lifetime.
And that will remove the ccache after a reboot, enlarge the compiling times massively.
Without a defined path the XDG_CACHE_HOME is used. But some users set XDG_CACHE_HOME to a path in tmpfs for a clean system between reboots and to enlarge their SSD lifetime. And that will remove the ccache after a reboot, enlarge the compiling times massively.