- 学习GCC Generating dependencies
1.Generating dependencies
命令如下所示:
- gcc -M 输出描述源文件的依赖关系。
- gcc -MM 与-M相似,只是不包含系统头文件
- gcc -MF file 将依赖关系写到文件file中
- gcc -MT target / -MQ target 重新定义目标对象名
- gcc -MD 等同于-M -MF file
2.案例Hello World程序如下:
/* main.c */
#include <stdio.h>
#include "main.h"
void main(void)
{
printf("%s\n", PRINT_STR);
}
/* main.h */
#define PRINT_STR "Hello World"
-M 参数实例 - 完整的头文件依赖关系
$ gcc -M main.c
~/Documents/work/code/makefile/temp$ gcc -M main.c
main.o: main.c /usr/include/stdc-predef.h /usr/include/stdio.h \
/usr/include/features.h /usr/include/x86_64-linux-gnu/sys/cdefs.h \
/usr/include/x86_64-linux-gnu/bits/wordsize.h \
/usr/include/x86_64-linux-gnu/gnu/stubs.h \
/usr/include/x86_64-linux-gnu/gnu/stubs-64.h \
/usr/lib/gcc/x86_64-linux-gnu/4.8/include/stddef.h \
/usr/include/x86_64-linux-gnu/bits/types.h \
/usr/include/x86_64-linux-gnu/bits/typesizes.h /usr/include/libio.h \
/usr/include/_G_config.h /usr/include/wchar.h \
/usr/lib/gcc/x86_64-linux-gnu/4.8/include/stdarg.h \
/usr/include/x86_64-linux-gnu/bits/stdio_lim.h \
/usr/include/x86_64-linux-gnu/bits/sys_errlist.h main.h
-MM 参数实例 - 不包含系统头文件的依赖关系
$ gcc -MM main.c
main.o: main.c main.h
-MF 参数实例 - 依赖关系被写入main.d中
$ gcc -MM main.c -MF main.d
$ cat main.d
main.o: main.c main.h
-MT 参数实例 - 目标对象由main.o变为了hello.o
$ gcc -MM main.c -MT hello.o
hello.o: main.c main.h