Issue with hide-ifdef and cc-mode

[Ergus]

Hi:

I am trying to use hide-ifdef to shadow code like:

#if 0
<code>
#endif

But I found that either

#if 0

or 

#if 1

produces the same result disabling the code inside.

Some slightly more complex examples like:

#define var 1
#ifdef var

doesn't work either (of course).

And when I try hif-evaluate-macro it says things like: 

false <= ‘#if 1’

or 

1 is not defined...

Do we have anything smarter in emacs to shows #if 0 codes? O is there
any extra customization or is there an issue in the package? any idea?

Also when I remove the #if macros from around the code the shadow face
persists.

Any help?