Targets using implicit extern "C"

[Joe Buck]

On Tue, May 10, 2005 at 02:26:12PM -0400, Ian Lance Taylor wrote:
> How would people feel about adding a configure option
> --with-implicit-extern-c?  Then we could justifiably flip the default
> for the generic *-elf, etc., targets.  In fact in general we could
> then take the macro out of the tm.h files and into config.gcc, which
> is probably a more reliable place to put it anyhow.

I think that the decision should be made at configure time, by checking
the #include headers to see if they are C++-ready.  Look for the string
"__cplusplus" in some set of standard headers, if it is not found,
assume that we'll need implicit extern C.  For cross-builds, we still
have a path to the headers to be checked.