[makefile]GNU-make-mannul-chapter8.9, LINK.o是什么变量？

nswcfd

http://www.gnu.org/software/make/manual/make.html#Eval-Function
页面加载时间较长，请耐心等待。在页面中搜索8.9即可。

8.9节介绍eval函数，其中加粗的部分，$(LINK.o)是什么？

此外，PROGRAM_template展开后，变成了
server: $(server_OBJS) $(server_LIBS:%=-l%)
斜体部分怎么理解？server依赖于-lpriv -lprotocol？感觉template的定义不完整？

1. PROGRAMS    = server client
   
2. 
   
3. server_OBJS = server.o server_priv.o server_access.o
   
4. server_LIBS = priv protocol
   
5. 
   
6. client_OBJS = client.o client_api.o client_mem.o
   
7. client_LIBS = protocol
   
8. 
   
9. # Everything after this is generic
   
10. 
    
11. .PHONY: all
    
12. all: $(PROGRAMS)
    
13. 
    
14. define PROGRAM_template =
    
15. $(1): $($(1)_OBJS) $($(1)_LIBS:%=-l%)     ############## server_LIBS/client_LIBS 这里替换为-l是什么意思？
    
16. ALL_OBJS   += $($(1)_OBJS)
    
17. endef
    
18. 
    
19. $(foreach prog,$(PROGRAMS),$(eval $(call PROGRAM_template,$(prog))))
    
20. 
    
21. $(PROGRAMS):
    
22.        $(LINK.o) $^ $(LDLIBS) -o $@        ################### 这里的LINK.o是什么预定义的变量？
    
23. 
    
24. clean:
    
25.         rm -f $(ALL_OBJS) $(PROGRAMS)

复制代码

nswcfd

第一个问题，明白了，4.5.6
4.5.6 Directory Search for Link Libraries

Directory search applies in a special way to libraries used with the linker. This special feature comes into play when you write a prerequisite whose name is of the form ‘-lname’. (You can tell something strange is going on here because the prerequisite is normally the name of a file, and the file name of a library generally looks like libname.a, not like ‘-lname’.)

When a prerequisite’s name has the form ‘-lname’, make handles it specially by searching for the file libname.so, and, if it is not found, for the file libname.a in the current directory, in directories specified by matching vpath search paths and the VPATH search path, and then in the directories /lib, /usr/lib, and prefix/lib (normally /usr/local/lib, but MS-DOS/MS-Windows versions of make behave as if prefix is defined to be the root of the DJGPP installation tree).

第二个问题，据实测，LINK.o的值就是CC的值，但是没有在文档中找到依据。

nswcfd

找到了，10.2 Catalogue of Built-In Rules

However, the recipes in built-in implicit rules actually use variables such as COMPILE.c, LINK.p, and PREPROCESS.S, whose values contain the recipes listed above.

make follows the convention that the rule to compile a .x source file uses the variable COMPILE.x. Similarly, the rule to produce an executable from a .x file uses LINK.x; and the rule to preprocess a .x file uses PREPROCESS.x.