Warn if `#' is preceded by whitespace?

[Kaveh R. Ghazi]

 > From: Zack Weinberg <zack@wolery.cumb.org>
 > 
 > On Wed, Feb 16, 2000 at 04:47:54AM -0200, Alexandre Oliva wrote:
 > > Wouldn't it be a good idea to emit a warning when the `#' of a CPP
 > > directive is not in the beginning of the line?
 > 
 > Certainly not with no way to turn it off!  It's explicitly
 > permitted by C89, and I've seen it used deliberately to hide
 > directives from K+R preprocessors.


Yes, e.g. SunOS4 cc doesn't understand #error, so you have to write it
like this:

#if condition
 #error "foo"
#endif

if you write

#if condition
#error "foo"
#endif

then you'll get "undefined control" even if the "condition" doesn't
trigger.



 > I'd suggest -Wtraditional only (which cpp doesn't know about right
 > now, but that can easily change).
 > zw


If we go with -Wtraditional, whose purpose is to make programs more
portable to traditional C, we should warn about whitespace preceeding
things like #if, #else and #endif, but warn about *missing* whitespace
in front of #error.  (We'll have to decide for any other directives
too whether they are traditional C or ANSI C directives and what to do
with each one.)  I.e. we might also want to warn about any uses at all
of e.g. #elif with -Wtraditional.

		--Kaveh
--
Kaveh R. Ghazi			Engagement Manager / Project Services
ghazi@caip.rutgers.edu		Qwest Internet Solutions