我试图了解Makefile应该是什么样子,当涉及到标志,尤其是链接标志时.这是我的Makefile：
OBJS = n.o
SOURCE = n.cpp
# HEADER = there are no header files,so I commented that
OUT = test
CXX = ../mpich-install/bin/mpic++
FLAGS = -I../intel/mkl/include ../intel/mkl/lib/intel64/libmkl_scalapack_ilp64.a -Wl,--start-group ../intel/mkl/lib/intel64/libmkl_intel_ilp64.a ../intel/mkl/lib/intel64/libmkl_core.a ../intel/mkl/lib/intel64/libmkl_sequential.a -Wl,--end-group ../intel/mkl/lib/intel64/libmkl_blacs_intelmpi_ilp64.a -lpthread -lm -ldl
all: $(OBJS)
$(CXX) $(OBJS) -o $(OUT) $(FLAGS)
# create/compile the individual files >>separately<<
n.o: n.cpp
$(CXX) -c n.cpp $(FLAGS)
.PHONY : all
# clean house
clean:
rm -f $(OBJS)
然后我得到：
../mpich-install/bin/mpic++ -c n.cpp -I../intel/mkl/include ../intel/mkl/lib/intel64/libmkl_scalapack_ilp64.a -Wl,--start-group ../intel/mkl/lib/intel64/libmkl_intel_ilp64.a ../intel/mkl/lib/intel64/libmkl_core.a ../intel/mkl/lib/intel64/libmkl_sequential.a -Wl,--end-group ../intel/mkl/lib/intel64/libmkl_blacs_intelmpi_ilp64.a -lpthread -lm -ldl
g++: warning: ../intel/mkl/lib/intel64/libmkl_scalapack_ilp64.a: linker input file unused because linking not done
g++: warning: ../intel/mkl/lib/intel64/libmkl_intel_ilp64.a: linker input file unused because linking not done
g++: warning: ../intel/mkl/lib/intel64/libmkl_core.a: linker input file unused because linking not done
g++: warning: ../intel/mkl/lib/intel64/libmkl_sequential.a: linker input file unused because linking not done
g++: warning: ../intel/mkl/lib/intel64/libmkl_blacs_intelmpi_ilp64.a: linker input file unused because linking not done
../mpich-install/bin/mpic++ n.o -o test -I../intel/mkl/include ../intel/mkl/lib/intel64/libmkl_scalapack_ilp64.a -Wl,--end-group ../intel/mkl/lib/intel64/libmkl_blacs_intelmpi_ilp64.a -lpthread -lm -ldl
这意味着我应该只在进程的最后部分使用一些标志.处理这种情况的正确方法是什么？也许创建FLAGS1和FLAGS2？它应该工作,但我想知道哪种方法正确.
“… but I want to know which the correct way.”
正确的方法是跟上make标准变量名,特别是CXXFLAGS和LDFLAGS.
您不想像尝试在此处那样指定链接器标志的库(实际指定主题)：
FLAGS = ... ../intel/mkl/lib/intel64/libmkl_scalapack_ilp64.a
您应该使用标准LDFLAGS makefile变量来设置路径,而不是使用FLAGS并提供直接主题进行链接,并让链接器找到适当的静态或共享库：
LDFLAGS += -L../intel/mkl/lib/intel64 -lmkl_scalapack_ilp64
# ^^^^^^^ Note the standard build system uses $(LDFLAGS) at the linker stage rule
# -L specifies the paths for finding libraries
# -l
区别于编译阶段标志(CXXFLAGS)和链接阶段标志(LDFLAGS).
在旁边：
为了避免这种情况
make -f Makefile clean
最终目标规则中的操作(可能已添加以避免错过以赶上标头依赖关系),向CXXFLAGS添加-MF选项,并包括结果.
以下是有关各种技术的更详细信息：
Auto-Dependency Generation
