C/C++, #Ifdef, working around the need for them

Consider the all to common code:

#ifdef HAVE_SOMETHING

something();

#endif

ifdef are problematic because any number of combinations of them can lead to multiple execution paths that the compiler never will so. PIA

The above assumes that HAVE_SOMETHING will have some value or not. 

Another option is the following:

if (HAVE_SOMETHING)

{

  something();

}

The significance in the above?

Any good compiler will evaluate HAVE_SOMETHING, and if the value is zero then the code path will be optimized out.

Awesome.