Fortran90 Makefile with pre-compilation and modules

Question

I'm trying to write a Makefile to compile a Fortran90 project that consists of several source files containing subroutines and modules. To make things more complicated, I'm using pre-compilation (creating *.for files from *.F files). I could not find any answer to this, but this may be because I get confused by the different styles of Makefile syntax.

I created a stripped-down version for reproducing my problem (available on https://github.com/stineb/stackoverflow). This contains a main program (sayhello.F), two subroutines in separate source files (schleppe.F and schnuppi.F), and two modules in separate source files (words_schleppe.mod.F and words_schnuppi.mod.F). The executable is hello.

I am able to build it with a simple Makefile and avoiding the pre-compilation. This file (Makefile_simple) looks like this:

FCOM=gfortran
EXE = hello

standard: 
    $(FCOM) -c words_schleppe.mod.F
    $(FCOM) -c words_schnuppi.mod.F
    $(FCOM) -c schleppe.F
    $(FCOM) -c schnuppi.F
    $(FCOM) words_schleppe.mod.o words_schnuppi.mod.o schleppe.o schnuppi.o sayhello.F -o $(EXE)

 .PHONY: clean
 clean:
    rm $(EXE) *.o *.mod

However, my project will be a bit bigger than this so I want to make use of the cryptic features of a more complex Makefile for defining rules. And crucially: I want to pre-compile source files *.F into .for. This is where I haven't managed to define the rules to create the .mod files from the modules and build the whole thing. Disregarding the modules, I do get it running with the following Makefile (Makefile_complex on my github repository):

FCOM=gfortran
CPPFLAGS=-e
COMPFLAGS=
EXE=hello
SOURCES=sayhello.F schleppe.F schnuppi.F 
OBJS=$(SOURCES:.F=.o)

all: $(OBJS)
    # this may also be replaced by the ar command (creating archive)
    $(FCOM) $(OBJS) -o $(EXE)

%.for: %.F
    rm -f $*.for
    $(FCOM) $(CPPFLAGS) $*.F > $*.for

$(OBJS): %.o: %.for
    $(FCOM) -c -o $@ $(COMPFLAGS) $*.for

# clean: remove .for, .o, .do, and .stb files
.PHONY: clean
clean:
    -rm -f *.for *.o *.stb *.mod

What do I have to add to this in order to include the modules in the build? The dependencies are as follows: subroutine schleppe <- module words_schleppe; and subroutine schnuppi <- module words_schnuppi.

Help, anyone? Thanks a bunch!

Answer 1

I FOUND THE SOLUTION! Simply, the rule for all: must include the module source files, and these must precede the other source files. Plus, rules of creating the object files from the module source files have to be added. The working Makefile looks like this:

FCOM=gfortran

CPPFLAGS=-E
COMPFLAGS=

EXE=hello

SOURCES=sayhello.F schleppe.F schnuppi.F
MODS=words_schleppe.F words_schnuppi.F

OBJS=$(SOURCES:.F=.o)
MODOBJS=$(MODS:.F=.o)

# this may also be replaced by the ar command (creating archive)
all: $(MODOBJS) $(OBJS)
    $(FCOM) $(OBJS) $(MODOBJS) -o $(EXE)

%.for: %.F
    rm -f $*.for
    $(FCOM) $(CPPFLAGS) $*.F > $*.for

$(MODOBJS): %.o: %.for
    $(FCOM) -c -o $@ $(COMPFLAGS) $*.for

$(OBJS): %.o: %.for
    $(FCOM) -c -o $@ $(COMPFLAGS) $*.for

# clean: remove .for, .o, .do, and .stb files
.PHONY: clean
clean:
    -rm -f *.for *.o *.stb *.mod