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

[zbeekman at gmail dot com]

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

--- Comment #3 from Zaak <zbeekman at gmail dot com> 2011-08-31 19:49:20 UTC ---
When I pass -E some strange behaviour occurs. First of all the code is
preprocessed with the c preprocessor and unless the -o flag is passed the
output is written to standard out, so this text will get included in the .d
dependency definition files which are to be included in the makefile. One can
avoid this issue if one passes -o /dev/null or does something clever with sed.
A second side effect of -E is that the module dependencies are no longer
included in the output which again renders this useless. After passing through
the sed command (as outlined in the GNU Make documentation) the last line of
modtypes.d went from:

modtypes.o types.mod: modtypes.f90

to

modtypes.o: modtypes.f90