OSX cannot link libwagyu without -lstdc++

[pramsey]

Seems like a platform difference, haven't seen this issue since we banished the GEOS c++ API many moons ago, but we cannot build --with-wagyu on OSX either (#4320) since that requires a link entry for libstdc++. The failure is in linking the postgis.so module, and it looks kind of like

  "std::logic_error::logic_error(char const*)", referenced from:
      std::__1::vector<mapbox::geometry::point<int>, std::__1::allocator<mapbox::geometry::point<int> > >::reserve(unsigned long) in libwagyu.a(lwgeom_wagyu.o)

etc, etc.

And it is fixed by adding -lstdc++ to the link line. Why are we not also seeing this kind of failure under Windows?

[pramsey]

Actually, -lc++ is considered more correct on OSX and also works

[Algunenano]

Why are we not also seeing this kind of failure under Windows?

I've only tested wagyu with a couple of Linux distributions and, for now, it's off by default, so it might be broken in Windows too.

This might have to do with postgis-3.so being generated with a C compiler which, by default, won't include libc++ or libstdc++. I'll try to find what's the proper way to address this.

[Algunenano]

PR in ​https://github.com/postgis/postgis/pull/371

[robe]

yah I haven't tested it on windows. Didn't even know it was committed already. thought it was still a pull request.

[Raul Marin]

In 17250:

Wagyu build improvements

Use same compiler as postgresql (adds extra -x cxx)
Pass the C++ standard library to postgres when linking wagyu

Closes #4321
Closes ​https://github.com/postgis/postgis/pull/371