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

我认为PCLint可以做到这一点,但我已经有几年没有研究它了。你可以去看看。

我看了这个博客,作者谈到了一些关于配置PCLint以查找未使用的包含的内容。也许值得一看。

其他回答

我认为PCLint可以做到这一点,但我已经有几年没有研究它了。你可以去看看。

我看了这个博客,作者谈到了一些关于配置PCLint以查找未使用的包含的内容。也许值得一看。

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。

有一个免费的工具包括文件依赖监视器,它可以集成到可视化工作室中。它用红色显示多余的#include。

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)

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.