make include directive and dependency generation with -MM
- by Robert S. Barnes
I want a build rule to be triggered by an include directive if the target of the include is out of date or doesn't exist.
Currently the makefile looks like this:
program_NAME := wget++
program_H_SRCS := $(wildcard *.h)
program_CXX_SRCS := $(wildcard *.cpp)
program_CXX_OBJS := ${program_CXX_SRCS:.cpp=.o}
program_OBJS := $(program_CXX_OBJS)
DEPS = make.deps
.PHONY: all clean distclean
all: $(program_NAME) $(DEPS)
$(program_NAME): $(program_OBJS)
$(LINK.cc) $(program_OBJS) -o $(program_NAME)
clean:
@- $(RM) $(program_NAME)
@- $(RM) $(program_OBJS)
@- $(RM) make.deps
distclean: clean
make.deps: $(program_CXX_SRCS) $(program_H_SRCS)
$(CXX) $(CPPFLAGS) -MM $(program_CXX_SRCS) > make.deps
include $(DEPS)
The problem is that it seems like the include directive is executing before the rule to build make.deps which effectively means make either getting no dependency list if make.deps doesn't exist or always getting the make.deps from the previous build and not the current one.
For example:
$ make clean
$ make
makefile:32: make.deps: No such file or directory
g++ -MM addrCache.cpp connCache.cpp httpClient.cpp wget++.cpp > make.deps
g++ -c -o addrCache.o addrCache.cpp
g++ -c -o connCache.o connCache.cpp
g++ -c -o httpClient.o httpClient.cpp
g++ -c -o wget++.o wget++.cpp
g++ addrCache.o connCache.o httpClient.o wget++.o -o wget++
