r224012 - Emit warning if define or undef reserved identifier or keyword.

[Joerg Sonnenberger]

On Mon, Dec 15, 2014 at 11:32:02AM -0500, Aaron Ballman wrote:
> On Sat, Dec 13, 2014 at 2:46 PM, Joerg Sonnenberger
> > (2) #define restrict __restrict__ --> code that has to deal with pre-C99
> > default in GCC.
> 
> I'm not certain this should have triggered the warning in the first
> place. Either restrict is a keyword (at which point, the #define
> should be considered possibly harmful), or restrict isn't a keyword
> (and then there's no reason for the warning in the first place).

It happens in code that has to deal with different compilers. Consider a
pre-generated config.h. In NetBSD we have to deal with different GCC
versions and Clang, at least the former doesn't default to C99 :(

> > (3) #define extern, #define static --> debug, code sharing
> 
> I think these should be a warning. If you're doing a debug build where
> you want to turn off keywords, you can add a -Wno-keyword-macro flag
> to your command line.

I disagree. Having to change the warning settings just to get a debug
build to work is stupid.

My question remains: what bugs has this warning caught? I've heard that
Microsoft believes this to be reasonable to warn about, but that's about
it.

Joerg