CODEWITHSUNDEEP
cmakefilecompiler-errorsshared-librariesstatic-libraries
WeakestTopology
WeakestTopology

Reputation: 153

C library, makefile header dependencies

Let' say I have library project with a few folders:

The problem is, everytime I change a header file and make doesn't perceive this (which is obvious why if you look at my Makefile) and says everything is up to date. I have manage to solve this with another project which wasn't a library, but with this one everytime I try something I end up with an error when the target is getting built. Here is the Makefile: 

CC=gcc
CFLAGS=-g -O2 -Wall -Iinclude -rdynamic -DNDEBUG $(OPTFLAGS)
LDFLAGS=$(OPTLIBS)

SOURCES=$(wildcard src/*.c)
OBJECTS=$(patsubst src/%.c,build/%.o,$(SOURCES))

TARGET=lib/libdatastruct.a
SO_TARGET=$(patsubst %.a,%.so,$(TARGET))

# The Target lib
all: $(TARGET) $(SO_TARGET)

dev: CFLAGS=-g -Wall -Iinclude -Wall -Wextra $(OPTFLAGS)
dev: all

$(TARGET): CFLAGS += -fPIC
$(TARGET): build $(OBJECTS)
    ar rcs $@ $(OBJECTS)
    ranlib $@
$(SO_TARGET): $(TARGET) $(OBJECTS)
    $(CC) -shared -o $@ $(OBJECTS)

build/%.o: src/%.c
    $(CC) $(CFLAGS) -o $@ -c $<

build:
    @mkdir -p lib
    @mkdir -p build

clean:
    rm -rf lib build

Upvotes: 0

Views: 2321

Answers (2)

WeakestTopology
WeakestTopology

Reputation: 153

I was able to solve this myself. Changed this:

build/%.o: src/%.c
    $(CC) $(CFLAGS) -o $@ -c $<

To this:

build/%.o: src/%.c
    $(CC) $(CFLAGS) -MMD -o $@ -c $<

include $(DEPS)

$(DEPS): ;

And added:

DEPS=$(patsubst %.o,%.d,$(OBJECTS))

After:

OBJECTS=$(patsubst src/%.c,build/%.o,$(SOURCES))

Upvotes: 1

2501
2501

Reputation: 25753

Generate a list of headers:

HEADERS := $(wildcard src/*.h)

and since you don't have any dependency files, simply ensure that all object files depend on all header files:

$(OBJECTS): $(HEADERS)

If any header is modified every object file is rebuild since any source file may include (and depend) on any header file.

If you don't want to rebuild everything after a header is changed, you can manually add specific dependencies, so that only the needed files are rebuilt. For example:

src/file.c: src/file.h
src/main.c: src/main.h src/file.h

Those dependencies can also be made automatically.

Upvotes: 0

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