[petsc-users] ``--with-clanguage=c++" turns on "PETSC_HAVE_COMPLEX"?

[Jed Brown]

Fande Kong via petsc-users <petsc-users at mcs.anl.gov> writes:

> It looks like mpicxx from openmpi does not handle this correctly. I
> switched to mpich, and it works now.
>
> However there is till some warnings:
>
> *clang-6.0: warning: treating 'c' input as 'c++' when in C++ mode, this
> behavior is deprecated [-Wdeprecated]*
> *         CXX arch-linux2-c-opt-memory/obj/dm/impls/plex/glexg.o*
> *         CXX arch-linux2-c-opt-memory/obj/dm/impls/plex/petscpartmatpart.o*
> *clang-6.0: warning: treating 'c' input as 'c++' when in C++ mode, this
> behavior is dep*

Clang has always done this.  I don't know a clean way to work around the
warning, but we don't recommend with-clanguage=c++ unless you're on a
platform where a sane C compiler doesn't exist.