I've installed new Fedora 14. It has a ccache-3.1.1 enabled by default for g++ (i.e. g++ points to /usr/lib/ccache/g++). The "g++ -fdump-translation-unit header.h" command generate a header.gch (precompiled header) and header.tu files (translation unit dump). But the second run of the same command will not generate a header.tu file. So, every tool that use this feature will be broken. For example ABI Compliance Checker is not working on Fedora 14 for this reason. I've checked other -fdump-* options - they all are broken.
Thanks for the bug report! I will fix this in ccache 3.1.2.
(And for the record: My opinion is actually that ccache should not be enabled by default. Not primarily because of potential bugs, but because it's not certain that enabling ccache will result in improved performance; if the user seldom recompiles, it will just be a waste of resources. http://ccache.samba.org/performance.html contains more thoughts on this.)
Fixed in 7041a5223c45a1907520285a0d12d814c1168d3a.
Included in ccache version 3.1.2.