[Bug fortran/91731] Configure error on building MPICH

[sgk at troutmask dot apl.washington.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91731

--- Comment #7 from Steve Kargl <sgk at troutmask dot apl.washington.edu> ---
On Thu, Sep 12, 2019 at 01:06:12AM +0000, damian at sourceryinstitute dot org
wrote:
> 
> --- Comment #6 from Damian Rouson <damian at sourceryinstitute dot org> ---
> Steve, I'm so incredibly glad you posted the details of your workaround.  
> Thank you! I had seen the FCFLAG environment variable, but I hadn't
> noticed the
> FFLAG variable listed just a few lines lower in the output of "configure
> --help".  I was pulling my hair out until I noticed that one extra character!
> 
> Also, what is -w doing? From your message on the email list, I'm guessing it

-w suppresses all warnings.  It is the only way (intentionally!) to
suppress the argument mismatch warning.

> converts an error message to a warning.  Is it needed with
> -fallow-argument-mismatch?

-fallow-argument-mismatch degrades the error to a warning.

> I don't find -w in the output of "gfortran --help"

It's a general gcc option.  Look in gcc.info.

> and I don't see it mentioned in gfortran's online documentation at
> https://gcc.gnu.org/onlinedocs/gfortran/Option-Summary.html.

General gcc options are not documented in the gfortran.info file.

I don't use mpich, but poking around in its scripts, I think 
that mpifort is the general script to compile a Fortran program.
This script does not honor FFLAGS.