[C PATCH] Add -Wincompatible-pointer-types option (PR c/58286)

[Joseph S. Myers]

On Mon, 30 Jun 2014, Marek Polacek wrote:

> This patch adds the -Wincompatible-pointer-types option for a warning
> we already have, so it's possible to suppress this specific warning, or
> use it with -Werror= and so on.
> As a followup change, I'm considering printing the types of the pointers;
> saying merely e.g. "assignment from incompatible pointer type" seems to be too
> austere.  (We say "expected T but argument is of type U" when passing arguments.)
> This is for C/ObjC only, since in C++, we'd issue "cannot convert" error.
> 
> Bootstrapped/regtested on x86_64-linux, ok for trunk?

OK with the documentation amended to make clear this is for the cases not 
covered by -Wno-pointer-sign (which in ISO C terms are just as 
incompatible as the cases covered by the new option).

-- 
Joseph S. Myers
joseph@codesourcery.com