Nick Papior wrote:
> Damnit, I was kind-of hoping this would not break compatibility. :(
>
> Then I guess I am forced to use cpp to create my actual sources.
>
> Thanks for the prompt answer!
>
> PS. Are there options to use the C-processor with gfortran?
> I tried:
> $> gfortran -Xpreprocessor "-x c11-cpp-input" <source>
> f951: Error: command line option ‘-x c11-cpp-input’ is valid for the
> driver but not for Fortran
>
> hrmph...
>
> 2016-02-19 20:30 GMT+01:00 Jonathan Wakely <jwakely.gcc@xxxxxxxxx>:
>> On 19 February 2016 at 19:01, Nick Papior wrote:
>>> Am I missing some point here?
>>> I would have expected gcc/gfortran to use the _same_ preprocessing
>>> utility as that provided in cpp?
>>
>> By default cpp works in C mode, but when invoked by the Fortran
>> front-end it runs in a different mode. If you use cpp -x f97-cpp-input
>> then it works in F95 mode, and you get results consistent with
>> invoking gcc on a .f file, or invoking gfortran.
>>
>> I don't know why cpp treats C and Fortran input differently, but
>> that's why you don't see what you expect.
>
>
>
> PS. Are there options to use the C-processor with gfortran?
With g77, if you named your src file with the .FPP extension, the
compiler would run the code through the c pre-processor and then compile
as fortran. This would let you use c style includes and compiler
directives for code compiled as fortran. You cannot use fortran style
includes in the same file (like a common statement), you have to choose
one or the other.
This is the make rule I used,
INCLUDES = -I ${SOURCELOC}/src_common_depend
OPTIMIZE = -O2
FCOMP = g77-3
FCFLAGS = $(INCLUDES) $(OPTIMIZE) -mno-cygwin
$(BDIR)/%.o: $(SOURCELOC)/%.FPP
$(FCOMP) $(FCFLAGS) -c -o $@ $<
the no-cygwin flag is depreciated and as I said, this example was for
gcc3/g77. I have done some of this with gfortran, but only for linux.
In some ways, it can be easier to separate your cpp and fortran code and
just have your fortran be a function called from cpp. Let the fortran
have it's own variable namespace and use the fortran pre-processor. As
long as you can send and return what you need to and from the fotrran
function, everything should work fine. It's not supper efficient since
the fortran and c code often have their own copies of each variable, but
that is often not a major issue anymore.
LMH
