Smart auto completion for C++ in Emacs

Many people have asked for C++ auto completion in Emacs. Until recently no really good alternative has been available. Parsing C++ is very hard and using tools like ctags works well for C but not so much for C++. CEDET/Semantics works for small C++ projects but is slow and quite complicated to install and configure.

LLVM/Clang is a compiler architecture supported by Apple that seeks to become a serious alternative to GCC. The project started just a few years ago but it already provides a high quality C and Objective C compiler that performs better than GCC in several benchmarks. The C++ support is still not complete but good enough to compile many parts of boost. Clang is not just a compiler, it also has includes great tools for code analysis. Clang is BSD licensed which enables close interaction with third part applications without licensing issues.

https://llvm.org/svn/llvm-project/cfe/trunk/utils/clang-completion-mode.el is a wonderful hack that lets Emacs interface with Clang. The result is great and fast auto completion inside Emacs. I’m sure we will see more uses of Clang in other projects.

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3 Responses to Smart auto completion for C++ in Emacs

  1. Needs this patch:

    diff -du /Users/dave/DropBox/home/.emacs.d/elhome/lib/clang-completion-mode.el /var/folders/w6/w6aHCL\+5EVeBUsDYKAF0pU\+\+\+TI/-Tmp-/buffer-content-97274uaK
    — /Users/dave/DropBox/home/.emacs.d/elhome/lib/clang-completion-mode.el 2010-01-13 01:44:51.000000000 -0500
    +++ /var/folders/w6/w6aHCL+5EVeBUsDYKAF0pU+++TI/-Tmp-/buffer-content-97274uaK 2010-12-07 14:17:02.000000000 -0500
    @@ -53,10 +53,10 @@
    :group ‘clang-completion-mode)

    ;;; Extra compilation flags to pass to clang.
    -(defcustom clang-flags “”
    +(defcustom clang-flags nil
    “Extra flags to pass to the Clang executable.
    This variable will typically contain include paths, e.g., -I~/MyProject.”
    – :type ‘string
    + :type ‘(repeat (string :tag “Argument” “”))
    :group ‘clang-completion-mode)

    ;;; The prefix header to use with Clang code completion.

    Diff finished. Tue Dec 7 14:17:02 2010

  2. kristianr says:

    Dave> Thanks. I just want to tell you that I’m not a maintainer or developer of this emacs mode. You should contact the llvm/clang-developers.

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