makefile 中定义宏位置需要注意一下

CUR_DIR = $(shell pwd)

CFLAGS = -g -Wall
GCC = gcc
GXX = g++

TARGET = exe.out

SRC_FILES += $(shell find $(CUR_DIR) -name *.cc) 
          += $(shell find $(CUR_DIR) -name *.cpp)

OBJS = fatal-impl.o log.o

INCLUDE += -I.
RM = rm -f

LINK = 
CFLAGS = -DNS3_LOG_ENABLE -g -Wall -O0

all: $(OBJS) test.o
    $(GXX) $(CFLAGS) $^ -o $(TARGET) $(LINK)

test.o: test.cpp
    $(GXX) -c $(CFLAGS) $^ -o $@
    
$(OBJS): %.o : %.cc 
    $(GCC) -c $(CFLAGS) $(INCLUDE) $< -o $@

.PHONY : clean
clean: 
    $(RM) $(OBJS)
    $(RM) $(TARGET)

上面-D选项放在-c选项前宏定义不起作用，修改放在-c选项后面后ok，

相当于在需要编译的文件最开始位置添加#define xxx