Re: G95: just say no to second underscore

Ed Hartnett wrote:
So I am going to leave things as they are, and let g95 users who want
to work with other packages set the flags as they wish. If you set
these flags before building netCDF, it will not try to override your
choices, so knowledgeable users can use the no-second-underscore flag
if they wish.

I have added the following note to the Porting and Installation Guide:

"GNU compilers, and the g95 fortran compiler, use the f2cFortran
flag. This is turned on automatically by configure.

Some g95 users recommend instead setting the following, which handles
the underscores differently, and reportedly works better when
integrating with other packages or libraries:

@example
CC=gcc
FC=g95
CPPFLAGS=-DpgiFortran
FFLAGS=-fno-second-underscore
FCFLAGS=-fno-second-underscore
@end example

If this approach is taken, all fortran programs which use netCDF must
be compiled with the -fno-second-underscore flag."
I think that is the best solution.

A clarification: Gfortran, aka Gnu Fortran 95, does *not* use the second underscore by default:

   
http://gcc.gnu.org/onlinedocs/gcc-4.1.1/gfortran/Code-Gen-Options.html#Code-Gen-Options

Since Gfortran has replaced G77 as the standard Fortran compiler in the GCC suite, your statement that "GNU compilers, [...], use the f2cFortran flag." is not correct.

As you are aware, the netCDF build system handles Gfortran correctly, i.e., it uses -DpgiFortran and generates symbols with a single underscore. The resulting library is not compatible with g77. I expect this will generate its own set of support questions.

--
Mark Hadfield          "Ka puwaha te tai nei, Hoea tahi tatou"
m.hadfield@xxxxxxxxxx
National Institute for Water and Atmospheric Research (NIWA)



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