Issue with hide-ifdef and cc-mode

[Ergus]

Hi:

I sent this message to the emacs-help mailing list some days ago and I
didn't receive any reply. So I'm resubmitting this here:

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... Unless the documentation says this function is
capable to understand some more complex constructions like ||, && and
arithmetic 

I only want to disable some code with #if 0 and enable it with #if
1... so my use case is probably the simplest one.

Do we have anything smarter in emacs to shows #if 0 codes? Or is there
any extra customization I am missing or is there any issue in the
package itself? any idea?

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

I would expect such a functionality to be implemented with fontlock or
so, but form an old thread in this mailing list I see that such a thing
is not recommended. But this package is not very documented in the
manual either so I am not sure If I am missing something.

Right now I have only these options:

```
(setq-default hide-ifdef-shadow t
              hide-ifdef-initially t)
```

Any help than? Should I submit a bug?

Thanks in advance,
Ergus