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

[Gabriel Dos Reis]

On Fri, Jun 15, 2012 at 4:48 AM, Richard Guenther
<richard.guenther@gmail.com> wrote:
> 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?

Agreed.  Including a standard header within a language specification is bogus.
If <string.h> is needed, just include it as such.   A standard header isn't
under our control (whether C or C++ is used is immaterial);
the whole justification of "don't want name mangling" is bogus.
If a standard header isn't needed; it should not be included.

-- Gaby