Side effects of pruning when doing 'clean all'.

[Michele Zamparelli]

 Hallo,

I have a makefile which works flawlessly when doing 'clean' and 'all', 
but which fails miserably when doing
'clean all'.

The reasons is pruning.
A clean subgoal deletes a generated C file (stack.c), which had been 
generated earlier on, at dependency inclusion time.
When executing the all target, make eventually tries to build an object 
file for a library, assuming that the generated C file is still there.

The C compiler is then called upon a non existing source file, and fails:

 make clean all
gcc -c -o stack.o stack.c
gcc: stack.c: No such file or directory
gcc: no input files
make: *** [stack.o] Error 1

This is happening because when evaluating the prerequisites of the 
object file, make decides to prune the C source file.

Here are a simplified makefile,  exhibiting the same behavior, and the 
output of a 'make -dr clean all'.

#
# Makefile model to exhibit make clean all failure
#
CCDEP = gcc -MM -MG -ansi

%.d: %.c
    @echo "== Dependencies C: $@"
    @$(CCDEP)  $(CFLAGS) $(I_PATH) $<   |  \
                   sed -e "s/$*\.o/$*.o $*.d /" \
                       -e "s/:/: Makefile /" > $@ ;     \
                       if [ ! -s $@ ]; then $(RM) $@ ; fi

%.o: %.c
    gcc -c -o $@ $<


# this is normally done by macro expansion for libraries, executables
# CORBA stubs generation etc. etc.
include stack.d

stack.c: stack.xml
    @echo "Simulating code generation"
    @cp stack.xml stack.c

stack: stack.o
    gcc  $(LD_FLAGS) -L/usr/lib  $< -o $@

.PHONY: all
all: stack

.PHONY: clean
clean:
    address@hidden stack.o stack stack.c stack.d


I must be overlooking something, possibly a better way to include the 
dependencies.
I also think that this problem (or a related one) has possibly already 
posted on this list, but I could not find it

Does anyone know a solution to this?
You will probably have spotted another flaw in this: the dependencies 
(gcc --MM) are automatically generated and included even when only 'make 
clean' is called, on a directory which is clean already.
Ideally I would like the 'include' directives to be called only as part 
of the 'all' target, but I understand this is conceptually not possible. 
Or is it?

We are using GNU make 3.81.

thanks in advance,

Michele

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