Using fypp through the Intel Fortran compilers about fypp HOT 5 OPEN

I had a look at it with a toy bash script as pre-processor. The ifort option seems to work somewhat differently from what is documented. It writes all the command line arguments it wants to pass to the pre-processor (including the source file name) into a file, and passes that file, prefixed with @ to the pre-processor. The pre-processor is supposed to recognize the @ prefix and treat the content of the file as command line arguments. While GNU cpp seems to be capable to do so (although, I did not find this feature anywhere documented), fypp is currently not.

One could, in theory, implement the same feature in Fypp (one would have to parse sys.argv before optparse sees it) and pass the extracted list of arguments to optparse. But first, it would be good to know, that this is the intended long term behavior of the ifort compiler...

from fypp.

So it actually uses response files? They were added also to GCC to support Windows platforms where command-line length limits exist. I small test on MacOS shows response files work here too:

ivan:~/fortran/legacy$ cat debug
-Wall -Werror -g
ivan:~/fortran/legacy$ gfortran @debug -v loop_cycle.f 
Driving: gfortran -Wall -Werror -g -v loop_cycle.f -mmacosx-version-min=12.5.0 -asm_macosx_version_min=12.5 -nodefaultexport -l gfortran -shared-libgcc
...

My initial goal was to write an ifort command wrapper or perhaps simply a configuration file to get a "natural" experience of using the fypp preprocessor without a separate generation step. While non-portable to some extent, it simplifies the writing of build-system files. (Since our cluster has Intel CPUs dominantly, the Intel Fortran compiler is the de-facto standard one, hence I'm willing to sacrifice portability for a nicer developer experience.)

from fypp.

I thought I'd mention that fpm on Windows also uses response files in the archiver and linker commands: fortran-lang/fpm#427. Given that fpm is in the process of adding a fypp wrapper (fortran-lang/fpm#729) it might become an issue for fpm sooner or later.

from fypp.

I've opened an issue about the undocumented behavior at the Intel Fortran Forum: https://community.intel.com/t5/Intel-Fortran-Compiler/Undocumented-behavior-of-fpp-with-alternative-preprocessor/m-p/1411981#M162675

from fypp.

One of the moderators replied that the documentation will be amended. The exact layout of the response file remains somewhat under-specified for my taste. More information can be found here:

• Use Response Files | Intel DPC++ Compiler
• @ (Specify a Compiler Response File) | MSVC Compiler Options
• The Response File Command | MIDL, Win32

The GCC mail archives state the contents of the file are whitespace-separated strings. Presumably, this would mean the separator between option strings are all the tokens recognized by the C library function isspace.

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