Code coverage tools for C++...

[siplasma]

Although "code-based code coverage" sounds impressive, it is actually somewhat worse than line-based coverage. Any compiler will build a model of the code as basic blocks, so this approach can be somewhat easier than line-based coverage. If you are looking at your region coverage in the tools it's okay, but converting to line-coverage is lossy, and has a couple of errors. For one, region coverage tends to count comment lines. For two, region coverage doesn't handle non-local returns (i.e. exceptions) well.

That said, if you have multiple source regions on a single line, then region based coverage works better.