Compiler support and recognition

[awvwgk]

Came up in #220.

At some point we might have to determine which compiler is used with fpm, therefore I tried to collect some information on the various Fortran compilers around. I only have first hand access to a fraction of them, so most of these information are second hand from HPC documentations or build systems.

Feel free to correct or add information to this table. Alternatively, we could move this table to the wiki.

vendor	Fortran compiler	C compiler	Module output directory	Module include directory	OpenMP	Free for OSS
Gnu	gfortran	gcc	-J	-I	-fopenmp	✔️
Intel	ifort	icc	-module	-I	-qopenmp	✔️
Intel (Windows)	ifort	icc	/module:path	/I	/Qopenmp	✔️
Intel oneAPI	ifx	icx	-module	-I	-qopenmp	✔️
PGI	pgfortran	pgcc	-module	-I	-mp	✔️
NVIDIA	nvfortran	nvc	-module	-I	-mp	✔️
LLVM flang	flang	clang	-module	-I	-mp	✔️
LFortran	lfortran	---	?	?	?	✔️
Lahey/Futjitsu	lfc	?	-M	-I	-openmp	?
NAG	nagfor	?	-mdir	-I	-openmp	❌
Cray	crayftn	craycc	-J	-I	-homp	?
IBM	xlf90	?	-qmoddir	-I	-qsmp	✔️
Oracle/Sun	?	?	-moddir=	-M	-xopenmp	?
Silverfrost FTN95	ftn95	?	?	/MOD_PATH	?	?
Elbrus	?	lcc	-J	-I	-fopenmp	?
Hewlett Packard	?	?	?	?	?	discontinued
Watcom	?	?	?	?	?	discontinued
PathScale	?	?	-module	-I	-mp	discontinued
G95	?	?	-fmod=	-I	-fopenmp	discontinued
Open64	?	?	-module	-I	-mp	discontinued
Unisys	?	?	?	?	?	discontinued

For now it might be sufficient to only support GCC, since we only guarantee that fpm works when compiled with GCC right now.

First class compiler support requires access to the compiler to allow testing in a CI environment, some of the commercial compilers have free versions for open source developers available.

[awvwgk]

Overview of compilers known by the meson build system can be found here, actual implementation is here.

[LKedward]

Awesome, thanks @awvwgk this is super useful! I've edited to include Intel differences on Windows.

[everythingfunctional]

Thanks for putting this together. It will be invaluable as we try to support more compilers.

[scivision]

• I have asked NAG to have free access for use in maintaining NAG support for Meson build system, but never got a reply. I did get replies to other email topics with NAG.
• Intel (non-oneAPI) is also free for OSS on Windows
• IBM XL is generally available at no cost assuming you have an IBM Power system to run it on.

[awvwgk]

I found that Ubuntu Focal (ubuntu-20.04 image) has a flang package available.

[scivision]

This Ubuntu flang possibly came from Debian. It might be quite out of date i.e. syntax bugs that might make issues for modern Fortran packages.

[rouson]

@awvwgk This has to be the most comprehensive listing of Fortran compilers that I've ever seen. Bravo!

[scivision]

Yes I think this would be great for the WIki insetad of Issue. Also, PGI is now also discontinued, replaced by NVIDIA

[awvwgk]

Feel free to create a wiki page for it, the wiki should be still world-editable.

[scivision]

The wiki isn't world editable

[awvwgk]

That can be fixed. Try again.