Matthew Knepley <[email protected]> writes:

On Sun, Dec 31, 2017 at 1:55 PM, Jed Brown <[email protected]> wrote:

...

These look like linker errors and that build uses --with-cxxlib-autodetect=0. We either need a rule to *link* C++ using CXX (i.e., mpicxx) or add LIBS=-lstdc++.

I thought we were doing this (linking C++ mains with CXX).

After compiling to the object file (ex3.o) we don't know what language main was written in, and this doesn't solve the actual problem that C++ linking is required if any object (not just main) depends on C++.