As part of the makefile i'd like to produce either a debug or release version of the target.
Functionally, everything is working, however, i am getting warnings when running make
12 SRC := $(shell echo src/*.cpp)
13 SRC += $(shell echo $(TEST_ROOT)/*.cpp)
14
15 D_OBJECTS = $(SRC:.cpp=.o) # same objects will need to be built differently
16 R_OBJECTS = $(SRC:.cpp=.o) # same objects will need to be built differently
22 all: $(TARGET)
23
25 $(TARGET): $(D_OBJECTS)
26 $(CC) $(D_OBJECTS) -o $(TARGET)
27
28 $(D_OBJECTS) : %.o: %.cpp # ----- run with debug flags
29 $(CC) $(COMMON_FLAGS) $(DEBUG_FLAGS) -c $< -o $@
30
31 release: $(R_OBJECTS)
32 $(CC) $(R_OBJECTS) -o $(TARGET)
33
34 $(R_OBJECTS) : %.o: %.cpp # ----- run with release flags
35 $(CC) $(COMMON_FLAGS) $(RELEASE_FLAGS) -c $< -o $@
When i make
i get debug version, when i make release
i get release version.
But i also get warnings:
Makefile:35: warning: overriding commands for target `src/Timer.o'
Makefile:29: warning: ignoring old commands for target `src/Timer.o'
Makefile:35: warning: overriding commands for target `test/TimerTest.o'
Makefile:29: warning: ignoring old commands for target `test/TimerTest.o'
With this 2 questions:
Like the OP (James Leonard), I would like to suppress or avoid warnings about overriding Makefile
targets. However, my situation and goals are different.
I want Makefile
to include base.mk
, and I want Makefile
to be able to override targets from base.mk
without any warning messages. I am using GNU Make.
The GNU Make documentation describes one way of doing this:
Create Makefile
as follows:
foo:
echo 'bar' > foo
%: force
@$(MAKE) -f base.mk $@
force: ;
Source: https://www.gnu.org/software/make/manual/html_node/Overriding-Makefiles.html
The above method has the (potentially serious) disadvantage that it will invoke a separate instance of $(MAKE)
, meaning that (some or all?) variables may (will?) not be shared between the parent and child invocations of make.
Happily, I found a better solution, as outlined below:
Create base.mk
as follows:
foo-default:
echo 'foo-default'
bar-default:
echo 'bar-default'
%: %-default
@ true
Create Makefile
as follows:
include base.mk
foo:
echo 'foo Makefile'
Example output:
$ make foo
echo 'foo Makefile'
foo Makefile
$ make bar
echo 'bar-default'
bar-default
Note that you need to be able to control the names of the targets in base.mk
so that you can name them <target>-default
. In other words, you cannot use this approach to extend arbitrary base makefiles. However, if you control both base.mk
and Makefile
, this approach will allow you to create one base.mk
and then many customizations of it.
One of the most common ways for doing this is to put the release objects and the debug objects in separate subdirectories. That way you don't get redefinitions for the rules for an object, since they will have different names. Something like this:
D_OBJECTS=$(SRC:%.cpp=debug/%.o)
R_OBJECTS=$(SRC:%.cpp=release/%.o)
RTARGET = a.out
DTARGET = a.out.debug
all : dirs $(RTARGET)
debug : dirs $(DTARGET)
dirs :
@mkdir -p debug release
debug/%.o : %.c
$(CC) $(DEBUG_CFLAGS) -o $@ -c $<
release/%.o : %.c
$(CC) $(RELEASE_CFLAGS) -o $@ -c $<
$(DTARGET) : $(D_OBJECTS)
$(CC) $(DEBUG_CFLAGS) -o $@ $(D_OBJECTS)
$(RTARGET) : $(R_OBJECTS)
$(CC) $(RELEASE_CFLAGS) -o $@ $(R_OBJECTS)
To avoid including the same file many times, you can use a C-style header 'directive':
ifeq ($(_MY_MAKEFILE_),)
_MY_MAKEFILE_ := defined
...
endif
ifeq
here is just saying "is the value empty"ifndef
but I got this working firstIf you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With