Static assertion (assert at compile time): static_assert

"C++ Programming Language (Fourth Edition)" Chapter 2.4.3

static_assert(A,S) A is a constant expression. When A is not true, the compilation fails, and S will be output as a compiler error message.

#define debug qDebug()<<

constexpr int C = 299792458;

void debugValue(int value)
{
    const int maxSpeed = 10000000000;
    static_assert(maxSpeed < C,"You can't go faster than the speed of light");
    debug "value = "<<value;
}

int main(int argc, char *argv[])
{
    debugValue(2);
}