boost libstdc++ issue (was libvisio error)

[David Evans]

On 9/6/15 10:42 AM, Brandon Allbery wrote:
> On Sun, Sep 6, 2015 at 1:36 PM, David Evans <devans at macports.org <mailto:devans at macports.org>> wrote:
> 
>     So the question is, why isn't this set by boost when compiling on Mac OS X configurations that use clang with
>     -stdlib=libstdc++ (Lion for instance).  Seems like there is possibly a mis-configuration in this case which could
>     have a wider effect more than just the ports referenced here.
> 
> 
> I think the problem is that boost will generally be installed with clang / libc++ support but is still visible to g++
> even if that is using libstdc++?
> 

Not sure I completely understand.

When compiling C++ programs the default compilers are to my understanding

	clang++, -stdlib=libc++  	for 10.9 +
	clang++, -stdlib=libstdc++	for 10.7, 10.8

On these platforms, again to my understanding, g++ is an alias for clang++
and shouldn't be used in any case per Ryan's https://trac.macports.org/wiki/UsingTheRightCompiler mandate.

It may be that boost is configuring for libc++ on 10.7, 10.8 instead of libstdc++ but, if that is the case, that is not
correct and would lead to the type of failure reported in this thread.

Also note that the issue here is the configuration of the boost headers not the boost libraries themselves.

For now, I'm not addressing the issue of earlier OS X versions, or MacPorts gcc versions which could be a different can
of worms altogether.

Dave