gcc - 链接器输入文件未使用，因为链接未完成 - gcc

Question

我是编写 makefile 的初学者。我有一个类似这样的 makefile:

PATH1 = /ref

CC=gcc
LINK = gcc

INCLUDES = .
INCLUDES += -I/PATH1/inc \
        -I/$(PATH1)/abc/inc/ \
        -I/$(PATH1)/def/inc/ 


all: src_file

run: src_file

src_file: 
    $(CC) $(INCLUDES) -MM  /ref/abcd.c -o $@ 

clean:
    rm -f *.o src_file

如果我执行 make，则会收到错误:

linker input file unused because linking not done.

我在 stackoverflow 上读了一些类似的帖子，但找不到解决方案。有人可以告诉我我的 makefile 有什么问题吗？提前致谢。

Answer 1

罪魁祸首是预处理器选项-MM。来自 gcc pre-processor options ,

-M

Instead of outputting the result of preprocessing, output a rule suitable for make describing the dependencies of the main source file. The preprocessor outputs one make rule containing the object file name for that source file, a colon, and the names of all the included files, including those coming from -include or -imacros command line options.

Passing -M to the driver implies -E, and suppresses warnings with an implicit -w.

-MM

Like -M but do not mention header files that are found in system header directories, nor header files that are included, directly or indirectly, from such a header.

因此，您实际上只是预处理，因此没有编译，没有链接以及由此产生的错误。