当变量定义有尾随空格时，如何阻止GNU Make执行 [英] How to prevent GNU Make from executing when a variable definition has trailing spaces

问题描述

我的makefile文件中有一个简单的变量定义:

THIS         := ~/edan 

并且该行中有尾随空格.

后来，当我根据此变量定义另一个变量时:

WARES       := $(THIS)/wares

定义的实际变量为/home/directory/edan wares

，然后make clean规则删除了/home/directory/edan，而不是我想要的.

如果一行中有尾随空格，如何阻止makefile执行?

解决方案

尽管您可以编写Makefile，以便它检查变量的尾部空白并在发现变量时退出，但是有更好的方法来处理这种情况. /p>

在这种情况下，我建议使用addsuffix函数对$(THIS)和/wares进行分类，而不是手动进行. addsuffix函数将为您去除尾随空格.换句话说:

WARES := $(addsuffix /wares,$(THIS))

如果您确实希望它在发现尾随空白时退出，则可以执行以下操作:

THIS := ~/edan
ifneq "$(THIS)" "$(strip $(THIS))"
    $(error Found trailing whitespace)
endif

I had a simple variable definition in my makefile:

THIS         := ~/edan 

and it had trailing spaces in the line.

Later, when I defined another variable in terms of this one:

WARES       := $(THIS)/wares

the actual variable defined was /home/directory/edan wares

and then the make clean rule removed /home/directory/edan instead of what I wanted it to.

How can I prevent a makefile from executing if a line has trailing spaces?

解决方案

Although you could write the Makefile so that it checks the variable for trailing whitespace and exits if it finds some, there are better ways of dealing with this situation.

In this instance, I would recommend using the addsuffix function to catenate $(THIS) and /wares instead of doing it manually. The addsuffix function will strip the trailing whitespace for you. In other words:

WARES := $(addsuffix /wares,$(THIS))

If you really want it to exit if it discovers trailing whitespace, you could do this:

THIS := ~/edan
ifneq "$(THIS)" "$(strip $(THIS))"
    $(error Found trailing whitespace)
endif

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