I’m sorry, but I can’t do your job for you (or rather, I can, but not for free) and it’s your job to diagnose problems in 3rd-party software.
I would start from checking that all files exist, and what kind of files they are (e.g. Cygwin emulates symlinks as files with special content), then using Process Monitor to find out what’s happening when the error occurs.
It looks like either your Ccache is a native Windows app and somehow gets fed a MinGW path (that it doesn’t understand) or a simulated symlink (which it doesn’t know how to deal with, either), or that g++ fails to invoke some of its underlying executables or is itself a broken symlink.