[C PATCH] Encode CPP options in c.opt

[Joseph S. Myers]

On Tue, 19 Aug 2014, Manuel López-Ibáñez wrote:

> The following patch adds a new CPP() to *.opt files that tells the
> options machinery to keep in sync libcpp options and GCC options.
> 
> This will allow us to fix a lot of latent bugs where CPP warnings do
> not follow the rules of other warnings options. In this patch, I only
> deal with Wvariadic-macros, but I will convert others in follow-up
> patches. (Nonetheless, help is very much appreciated. There are a lot
> of them.)
> 
> For Wvariadic-macros, the c.opt and the documentation says it is
> enabled by default, but this was not true. It is only enabled if
> -Wpedantic or -Wtraditional are given. Worse, even if you give
> -Wvariadic-macros, the warnings were not enabled. Of course, neither
> #pragmas nor other nice things worked. All this is simply fixed by
> using the common machinery and just taking care of keeping libcpp and
> gcc in sync.
> 
> Bootstrapped and regression tested on x86_64-linux-gnu.
> 
> OK?

OK.

-- 
Joseph S. Myers
joseph@codesourcery.com