我经常发现文件的头部分总是变得越来越大,但它从来没有变小过。在源文件的整个生命周期中,类可能会被移动和重构,并且很可能有相当多的#include不需要存在。保留它们只会延长编译时间,并增加不必要的编译依赖关系。试图找出哪些仍然需要是相当乏味的。

是否有某种工具可以检测多余的#include指令,并建议哪些我可以安全地删除? 棉绒会这样吗?


当前回答

The problem with detecting superfluous includes is that it can't be just a type dependency checker. A superfluous include is a file which provides nothing of value to the compilation and does not alter another item which other files depend. There are many ways a header file can alter a compile, say by defining a constant, redefining and/or deleting a used macro, adding a namespace which alters the lookup of a name some way down the line. In order to detect items like the namespace you need much more than a preprocessor, you in fact almost need a full compiler.

Lint更多的是一个样式检查器,当然不会有这个完整的功能。

我想你会发现检测多余include的唯一方法是删除、编译和运行套件。

其他回答

也许有点晚了,但我曾经找到一个WebKit perl脚本,它做的正是你想要的。我相信它需要一些调整(我不太精通perl),但它应该能做到:

http://trac.webkit.org/browser/branches/old/safari-3-2-branch/WebKitTools/Scripts/find-extra-includes

(这是一个旧的分支,因为trunk不再有文件了)

很抱歉(再次)在这里发帖,人们通常不扩展评论。

检查我对crashmstr的评论,FlexeLint / PC-Lint会为你做这件事。信息信息766号。我的手册(8.0版)的11.8.1节讨论了这个问题。

另外,这一点很重要,不断迭代,直到消息消失。换句话说,在删除了不需要的头文件后,重新运行lint,一旦删除了一些不需要的头文件,更多的头文件可能已经成为“不需要的”。(这可能听起来很傻,慢慢读并分析它,这是有道理的。)

The problem with detecting superfluous includes is that it can't be just a type dependency checker. A superfluous include is a file which provides nothing of value to the compilation and does not alter another item which other files depend. There are many ways a header file can alter a compile, say by defining a constant, redefining and/or deleting a used macro, adding a namespace which alters the lookup of a name some way down the line. In order to detect items like the namespace you need much more than a preprocessor, you in fact almost need a full compiler.

Lint更多的是一个样式检查器,当然不会有这个完整的功能。

我想你会发现检测多余include的唯一方法是删除、编译和运行套件。

您可以编写一个快速脚本,删除单个#include指令,编译项目,并在没有发生编译错误的情况下记录#include中的名称和它被删除的文件。

让它在晚上运行,第二天你就会有一个100%正确的可以删除的包含文件列表。

有时候蛮力很管用:-)


编辑:有时它不会:-)。下面是一些来自评论的信息:

Sometimes you can remove two header files separately, but not both together. A solution is to remove the header files during the run and not bring them back. This will find a list of files you can safely remove, although there might a solution with more files to remove which this algorithm won't find. (it's a greedy search over the space of include files to remove. It will only find a local maximum) There may be subtle changes in behavior if you have some macros redefined differently depending on some #ifdefs. I think these are very rare cases, and the Unit Tests which are part of the build should catch these changes.

这不是自动的,但是doxygen会为#included文件生成依赖关系图。你必须从视觉上看它们,但它们对于了解什么在使用什么是非常有用的。