继续翻译
4.5.5 Directory Search and Implicit Rules ----------------------------------------- The search through the directories specified in `VPATH' or with `vpath' also happens during consideration of implicit rules (*note Using Implicit Rules: Implicit Rules.). For example, when a file `foo.o' has no explicit rule, `make' considers implicit rules, such as the built-in rule to compile `foo.c' if that file exists. If such a file is lacking in the current directory, the appropriate directories are searched for it. If `foo.c' exists (or is mentioned in the makefile) in any of the directories, the implicit rule for C compilation is applied. The recipes of implicit rules normally use automatic variables as a matter of necessity; consequently they will use the file names found by directory search with no extra effort.
4.5.5 目录搜索与隐式规则
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对 VPATH 或者 vpath 中所指定的目录，隐式规则运行时也会发生(*note Using Implicit Rules: Implicit Rules.)
例如，当一个 foo.o 文件没有显式规则，make 就考虑隐式规则，就好像是编译 foo.c 文件的内建规则。
如果一个文件不在当前目录，将会寻找其他目录，如果此foo.c 文件存在(或者被 makefile提及)，C 编译的隐式规则将被应用。
隐式规则的片段正常使用自动变量作为必须的因素；它们将用目录搜索的文件名而不需要额外的设定。
后文待续
本文转自健哥的数据花园博客园博客，原文链接：http://www.cnblogs.com/gaojian/archive/2012/09/20/2694606.html，如需转载请自行联系原作者
