Conding style question regarding configuration

[Pascal Van Leeuwen <pvanleeuwen@insidesecure.com>]

Hi,

Quick question regarding how to configure out code depending on a CONFIG_xxx 
switch. As far as I understood so far, the proper way to do this is not by
doing an #ifdef but by using a regular if with IS_ENABLED like so:

if (IS_ENABLED(CONFIG_PCI)) {
} 

Such that the compiler can still check the code even if the switch is 
disabled. Now that all works fine and dandy for statements within a
function, but how do you configure out, say, global variable definitions
referencing types that are tied to this configuration switch? Or should
I just leave them in, depending on the compiler to optimize them away?

Obviously the code depends on those variables again, so if it's not
done consistently the compiler will complain somehow if the switch is not 
defined ...

Also, with if (IS_ENABLED()) I cannot remove my function prototypes,
just the function body. Is that really how it's supposed to be done?

Regards,
Pascal van Leeuwen
Silicon IP Architect, Multi-Protocol Engines @ Inside Secure
www.insidesecure.com