Why this project
I use heavily emacs, and I need completion. I found that vim use clang to have a good completion process, and I think Emacs should use it too.
There is already a library which use it, but it is not exactly what I want. So I fork it. Original can be found here: `https://llvm.org/svn/llvm-project/cfe/trunk/utils/clang-completion-mode.el’
You need to have a working version of clang.
NOTE: On my computer, a clang 2.9 does not signal any error. The clang 3.0 signals it.
Because I use clang to know if there is any errors, it is normal if no errors are signaled by this library if clang is not at a correct version.
You also need yasnippet to use this library. It is the way chosen to complete.
To install it, you have to load anything.el and clang-completion-mode.el.
(load-file “/path/to/anything.el”) (load-file “/path/to/clang-completion-mode.el”)
And that’s all you need to have a correct install.
How to use it
In the global case (no specific flags)
You have only one command to remember. “clang-complete”. You just have to write some stuff, and then hit “M-x clang-complete”, a new window will appear with the possibilities and the errors. You can navigate with the arrows, and reduce the possibilities by writing in the minibuffer.
The way chosen if there is errors, is to not provide initial pattern. Otherwise it happens that you can see the error.
If you choose an error, Emacs will set the cursor to the position of the error. Otherwise it will complete.
In a real-life project, there is a lot of flags to set. Typically “-I” or “-D”.
To solve this issue, clang-complete uses the “.dir-locals.el” functionality. Emacs provide a way to set directory local variable. This is what we are using. A typical example is to have a .dir-locals.el file in the root of your project, and to put here all your flags. If your project is huge, and you can’t put too much flags, you have the possibility to make per-directory files.
You can find some use case in the example directory.
The interest of this example is that mysource uses “<>” to include myheader. So we must have to set some flags to clang. We can find the way to do this in the file examples/.dir-locals.el.
We define two Foo class. One in the namespace foo, the other in the global namespace.
We can see that there is no .dir-locales in this directory, but Emacs looks in the myproject directory. So it is okay.
This example is here to show that clang-complete is able to find the right completion for the two without any error.
The seconddir is here to show that clang-complete is not fooled by template. Even with specialization.
Currently clang-complete create some useless window. We need to delete them in the aim to do not flood the buffer number.
We are using clang directly, but it parses everything at every call, which is a very huge problem when the compilation time is not .
We must find a way to use “libclang” instead.