On Tue, Apr 10, 2007 at 10:47:21AM -0700, Jeremy Fitzhardinge wrote:
> Andrew Morton wrote:
> > #define AUDIT_FIRST_USER_MSG 1100 /* Userspace messages mostly
> > uninteresting to kernel */
> > #define AUDIT_USER_AVC 1107 /* We filter this differently */
> > #define AUDIT_LAST_USER_MSG 1199
> >
> > and CPP turns that into
> >
> > case 1100 ...1199:
> > case 2100 ...2999:
> >
> > and it does the same when the comments are stripped from the #defines.
> >
> > So we were saved by the trailing space which cpp added to the expanded
> > macro. I wonder why cpp did that, and to what extent one can rely cpp
> > doing that.
>
> I think its required to. If it didn't, it would be effectively pasting
> two tokens together without the ## operator.
Internally, there are lists of tokens and no ambiguities. What gcc docs
warn about is that
case 1...2:
will be parsed as
case
[space]
1.
.
.2
:
which won't fly.
> But putting spaces in is safer - or putting () around the numbers.
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