This is a new static analyzer checker that warns when there is loss of sign and loss of precision.
It is similar in spirit to Wsign-compare/Wsign-conversion etc. But this checker uses proper analysis so the output is much more meaningful.
It has been tested on debian packages.
loss of precision results:
2195 projects, 1026 warnings
loss of sign results:
2195 projects, 3613 warnigs
It seems to me that this checker shows that Clang does not always properly track values. It seems to think that result of ! can be negative for instance.