This is how make is defined to work. A rule like this: foo bar baz : boz ; $(BUILDIT) is exactly equivalent, to make, to writing these three rules: foo : boz ; $(BUILDIT) bar : boz ; $(BUILDIT) baz : boz ; $(BUILDIT) There is no way (in GNU make) to define an explicit … Read more
I use a file to remember the last value of such options, like this: .PHONY: force compiler_flags: force echo ‘$(CC_FLAGS)’ | cmp -s – $@ || echo ‘$(CC_FLAGS)’ > $@ The cmp || echo bit means the file compiler_flags is only touched when the setting changes, so now you can write something like $(OBJECTS): compiler_flags … Read more
It means “don’t echo this command on the output.” So this rule is saying “execute the shell command : and don’t echo the output. Of course the shell command : is a no-op, so this is saying “do nothing, and don’t tell.” Why? The trick here is that you’ve got an obscure combination of two … Read more
You can print out variables as the makefile is read (assuming GNU make as you have tagged this question appropriately) using this method (with a variable named “var”): $(info $$var is [${var}]) You can add this construct to any recipe to see what make will pass to the shell: .PHONY: all all: ; $(info $$var … Read more
Another way to suppress the make: error … (ignored) output is to append || true to a command that could fail. Example with grep that checks for errors in a LaTeX log file: undefined: @grep -i undefined *.log || true Without the || true, make complains when grep fails to find any matches. This works … Read more
The concept is called pattern rules. You can read about it in GNU make manual. $(GRAPHDIR)/%.png: $(GRAPHDIR)/%.dot dot $< -Tpng -o $@ graphs: $(patsubst %,$(GRAPHDIR)/%.png, Complex Simple IFileReader McCabe)\ or just %.png: %.dot dot $< -Tpng -o $@ graphs: $(patsubst %,$(GRAPHDIR)/%.png, Complex Simple IFileReader McCabe) You can also remove all repetition by extracting one of … Read more
I am fairly sure this will work: make VERBOSE=1 You should also be able to add this to your CMakeLists.txt to permanently set that: set(CMAKE_VERBOSE_MAKEFILE on) This is covered in the CMake FAQ.
There’s more than one way to do it, but this is a pretty good one (I really should have that hotkeyed). vpath %.cpp ../src src = Foo.cpp Bar.cpp test_src = Main.cpp FooTest.cpp BarTest.cpp objects = $(patsubst %.cpp,obj/%.o,$(src)) test_objects = $(patsubst %.cpp,obj/%.o,$(test_src)) $(objects): | obj obj: @mkdir -p $@ obj/%.o : %.cpp @echo $< @$(CXX) $(CXXFLAGS) … Read more
There are various problems with doing the sub-make inside a for loop in a single recipe. The best way to do multiple subdirectories is like this: SUBDIRS := $(wildcard */.) all: $(SUBDIRS) $(SUBDIRS): $(MAKE) -C $@ .PHONY: all $(SUBDIRS) (Just to point out this is GNU make specific; you didn’t mention any restrictions on the … Read more
You can use Target-specific Variable Values. Example: CXXFLAGS = -g3 -gdwarf2 CCFLAGS = -g3 -gdwarf2 all: executable debug: CXXFLAGS += -DDEBUG -g debug: CCFLAGS += -DDEBUG -g debug: executable executable: CommandParser.tab.o CommandParser.yy.o Command.o $(CXX) -o output CommandParser.yy.o CommandParser.tab.o Command.o -lfl CommandParser.yy.o: CommandParser.l flex -o CommandParser.yy.c CommandParser.l $(CC) -c CommandParser.yy.c Remember to use $(CXX) or $(CC) … Read more