[Bug fortran/49149] Dependency autogeneration with `-M` rendered useless by requiring .mod files

["sgk at troutmask dot apl.washington.edu" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49149

--- Comment #10 from Steve Kargl <sgk at troutmask dot apl.washington.edu> 2011-08-31 22:45:41 UTC ---
On Wed, Aug 31, 2011 at 10:27:40PM +0000, zbeekman at gmail dot com wrote:
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49149
> 
> --- Comment #8 from Zaak <zbeekman at gmail dot com> 2011-08-31 22:27:40 UTC ---
> (In reply to comment #7)
> > On Wed, Aug 31, 2011 at 10:01:06PM +0000, zbeekman at gmail dot com wrote:
> > > 
> > > I hope you are less confused now.
> > > 
> > 
> > I'm not confused.  I do, however, use the grey matter
> > between my ears to write my Makefiles.
> > 
> > gfortran requires that the *.mod are present to
> > parse your code.  Sorry if you cannot deal with 
> > that fact.
> 
> I didn't mean any insult, I am not trying to troll or start a flame war. I'm
> sorry if I offended you in any way. I would appreciate you telling me why you
> think my makefile is wrong rather than just insulting me. Did you read the link
> to the GNUmake manpage? Did you try executing the command outside of the
> makefile?

Yes, I scanned the GNU Make info file.  I can find no information 
in that file concerning Fortran modules.

I also scanned the GNU Fortran info file.  I can find no mention of
using -M to build the dependence for Fortran modules.  In fact,
-M does not appear anywhere in the GNU Fortran info file.  So, 
one needs to peer into the GNU GCC info file.

`-M'
     Instead of outputting the result of preprocessing, output a rule
     suitable for `make' describing the dependencies of the main source
     file.  The preprocessor outputs one `make' rule containing the
     object file name for that source file, a colon, and the names of
     all the included files, including those coming from `-include' or
     `-imacros' command line options.

Hmmm, no mention of a Fortran 'USE' statement.  A 'USE' statement
is a different beast than an 'INCLUDE' statement.

> How would you write a makefile to automatically build fortran codes, and
> resolve their dependencies without explicitly hand coding the dependencies?

Well, as I write the Makefile, I automatically write the correct
dependency.  I do not depend on an inadequate tool to do the 
work for me.  If you absolutely must have a tool, google makedepf90.

PS: *.mod files are binary files.