#include <string>

// this global string causes gcov to think there's executable lines
// beyond the end of the file, and that they have not been executed
std::string globalVar = "";

std::string
doSomething()
{
    // instantiating this string and calling a method on it causes the
    // 'return' line to be marked as having never been executed
    std::string localVar;
    localVar.size();
    return localVar;
}

int
main(int, char **)
{
    doSomething();
    return 0;
}

produces the wrong results:

a) it says that the return is never called
b) it executes past the end of the file