Re: fortran modules

[Michael R Nolta]

Alexandre Duret-Lutz wrote:
> > > > "Michael" == Michael R Nolta <address@hidden> writes:
>
>  Michael> Hi,
>  Michael> To get automake/autoconf to work with my simple f90 project, I had to
>  Michael> add a check for whether the module filenames are capitalized or not.
>
>  Michael> If you're not familiar with fortran, f90 module files are like C
>  Michael> header files; however, they're generated at compile time and not
>  Michael> written by the programmer. Also, the file format is compiler
>  Michael> dependent, so you can't precompute them.
>
> Are they built as a side effect of a .f90->.o compilation, or do they
> use a different build rule?

Yes, they're a side-effect of .f90 -> .o, and don't need a special rule.

> In the former case, do all .f90 files produce a module, or is their
> an easy way to know which do and which don't?

Not all files produce modules; only files containing "module x ... end 
module" blocks do. And there can be multiple module definitions per 
file. While *.mod files can be thought of like C headers, a module 
itself is more like a C++ namespace.

> These dependencies (whatever they are) ought to be captured by
> the Makefile.  Presently it's not clear how that is done.

Maybe something like:

        include_FCMODULES = dummy.mod
        dummy_mod_SOURCES = dummy.f90

>  Michael> In addition, the actual module filename isn't standard. For example,
>  Michael> if I have "module dummy" in the source, the SGI IRIX and Intel ifc
>  Michael> compilers spit out "DUMMY.mod", while the Portland pgf90 compiler
>  Michael> produces "dummy.mod".
>
>  Michael> So to work around this, I put this in Makefile.am:
>
>  Michael> EXTRA_HEADERS = dummy.mod DUMMY.mod
>  Michael> include_HEADERS = @DUMMY_MOD@
>
> This means you'll distribute dummy.mod and DUMMY.mod, but
> install only one of them.  Since you say they should be
> precomputed I believe you do not want to distribute them.
>
> That would be just
>
>   nodist_include_HEADERS = $(DUMMY_MOD)
>
> [...]

Yes, you're right. Should I say "nodist_EXTRA_HEADERS = ..." too?

>  Michael> where AC_PROG_FC_UPPERCASE_MOD is a macro I wrote to check which
>  Michael> convention the f90 compiler uses [attached].
>
> You should probably augment it with ([ACTION-IF-UPPERCASE], [ACTION-IF-NOT])
> arguments and submit it to Autoconf.
>
>  Michael> A couple of questions:
>
>  Michael> * Is this the best way to do this given the current versions of
>  Michael> autoconf/make? In other words, is their a feature I don't know about
>  Michael> which makes this rigamarole unnecessary?
>
> Can't think of any.
>
> Another idea is to write a install-data-local rule instead.  This way
> you do not have to list all these modules in configure.ac; however
> you have to write all the install code.  It's a tradeoff.
>
>  Michael> * Since this is a pretty common idiom, would it make sense to extend
>  Michael> automake to know about Fortran modules? I coudl say instead,
>
>  Michael> include_MODULES = dummy
>
>  Michael> and automake could then automagically determine the right filename
>  Michael> depending on which compiler is being used.
>
> That makes sense to me.  _MODULES might be a bit too generic; perhaps
> that could be
>
>   include_FCMODULES = dummy.mod
>
> (Adding `.mod' does not make uppercasing really harder, but
> I think it makes the Makefile.am more readable.)