Re: [Patch 4.6] In system.h, wrap include of C++ header in 'extern C++'

[Richard Guenther <richard dot guenther at gmail dot com>]

On Fri, Jun 15, 2012 at 11:27 AM, Duncan Sands <baldrick@free.fr> wrote:
> My plugin is written in C++. ?When including headers from gcc-4.6 it wraps
> them
> in 'extern "C"' to prevent name mangling. ?Some of the plugin headers
> include
> gcc/system.h which includes the C++ header cstring if it detects the use of
> a
> C++ compiler. ?As a result cstring routines included this way end up wrapped
> in
> 'extern C', while those included directly from C++ aren't 'extern C'. ?This
> doesn't worry g++, but clang gets upset, erroring out with a complaint about
> multiple inconsistent declarations of memchr and friends. ?Is the following
> patch OK to apply to gcc-4.6? ?And is it in principle OK to apply to gcc-4.7
> (I didn't test it there yet)? ?It would be useful if gcc-4.7 is compiled as
> C.

Uh, I don't think we should do that.  Why do we include cstring here anyways?

Ian - you added this include in rev. 167764, I don't think that was "proper".
But I'm not sure wrapping a system.h include inside extern "C" from a C++
plugin is proper either ...

Thanks,
Richard.

> Thanks, Duncan.
>
> Index: gcc/system.h
> ===================================================================
> --- gcc/system.h ? ? ? ?(revision 188518)
> +++ gcc/system.h ? ? ? ?(working copy)
> @@ -191,7 +191,9 @@
> ?#endif
>
> ?#ifdef __cplusplus
> +extern "C++" {
> ?# include <cstring>
> +}
> ?#endif
>
> ?/* Some of glibc's string inlines cause warnings. ?Plus we'd rather