[petsc-dev] Building Sowing fails with old system gcc

[Satish Balay]

On Thu, 3 Dec 2020, Blaise A Bourdin wrote:

> Hi,
> 
> Building sowing fails when I try to compile petsc on a RHEL7 system with the default gcc (4.8.5) and intel compilers.
> Looking at the log file and sowing.py, it looks like sowing configure step does not inherit from the compilers detected by BuildSystem at an earlier stage, so that instead of using the intel compilers, it pulls my ancient gcc.
> 
> Instead of having to clumsily add --download-sowing-cc=mpicc --download-sowing-cxx=mpicxx to the configure options, would it make sense to populate the CC, CXX, CPP, CXXPP configure options (sowing.py:40-47) with the PETSc compilers? I can do it if that is OK.

The reason for the current design is - sowing [and similar build tools] - are for the build machine - and the petsc library [and CC etc] are for the compute machine [in cases where these are different].

Also sowing didn't work with most compilers - and default gcc [from PATH] was the most sane default compiler for it.

And defaults don't always work [if defaults are changed - if might fix this senario - but break in others that are curently working...] - hence we have these extra options for use - in these cases.

I'm surprised sowing doesn't work with gcc-4.8.5. I'll have to recheck.

Satish