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1===================2Clang-Include-Fixer3===================4 5.. contents::6 7One of the major nuisances of C++ compared to other languages is the manual8management of ``#include`` directives in any file.9:program:`clang-include-fixer` addresses one aspect of this problem by providing10an automated way of adding ``#include`` directives for missing symbols in one11translation unit.12 13While inserting missing ``#include``, :program:`clang-include-fixer` adds14missing namespace qualifiers to all instances of an unidentified symbol if15the symbol is missing some prefix namespace qualifiers.16 17Setup18=====19 20To use :program:`clang-include-fixer` two databases are required. Both can be21generated with existing tools.22 23- Compilation database. Contains the compiler commands for any given file in a24 project and can be generated by CMake, see `How To Setup Tooling For LLVM`_.25- Symbol index. Contains all symbol information in a project to match a given26 identifier to a header file.27 28Ideally both databases (``compile_commands.json`` and29``find_all_symbols_db.yaml``) are linked into the root of the source tree they30correspond to. Then the :program:`clang-include-fixer` can automatically pick31them up if called with a source file from that tree. Note that by default32``compile_commands.json`` as generated by CMake does not include header files,33so only implementation files can be handled by tools.34 35.. _How To Setup Tooling For LLVM: https://clang.llvm.org/docs/HowToSetupToolingForLLVM.html36 37Creating a Symbol Index From a Compilation Database38---------------------------------------------------39 40The include fixer contains :program:`find-all-symbols`, a tool to create a41symbol database in YAML format from a compilation database by parsing all42source files listed in it. The following list of commands shows how to set up a43database for LLVM, any project built by CMake should follow similar steps.44 45.. code-block:: console46 47 $ cd path/to/llvm-build48 $ ninja find-all-symbols // build find-all-symbols tool.49 $ ninja clang-include-fixer // build clang-include-fixer tool.50 $ ls compile_commands.json # Make sure compile_commands.json exists.51 compile_commands.json52 $ path/to/llvm/source/clang-tools-extra/clang-include-fixer/find-all-symbols/tool/run-find-all-symbols.py53 ... wait as clang indexes the code base ...54 $ ln -s $PWD/find_all_symbols_db.yaml path/to/llvm/source/ # Link database into the source tree.55 $ ln -s $PWD/compile_commands.json path/to/llvm/source/ # Also link compilation database if it's not there already.56 $ cd path/to/llvm/source57 $ /path/to/clang-include-fixer -db=yaml path/to/file/with/missing/include.cpp58 Added #include "foo.h"59 60Integrate with Vim61------------------62To run `clang-include-fixer` on a potentially unsaved buffer in Vim. Add the63following key binding to your ``.vimrc``:64 65.. code-block:: console66 67 noremap <leader>cf :pyf path/to/llvm/source/clang-tools-extra/clang-include-fixer/tool/clang-include-fixer.py<cr>68 69This enables `clang-include-fixer` for NORMAL and VISUAL mode. Change70`<leader>cf` to another binding if you need clang-include-fixer on a different71key. The `<leader> key72<http://vim.wikia.com/wiki/Mapping_keys_in_Vim_-_Tutorial_(Part_3)#Map_leader>`_73is a reference to a specific key defined by the mapleader variable and is bound74to backslash by default.75 76Make sure vim can find :program:`clang-include-fixer`:77 78- Add the path to :program:`clang-include-fixer` to the PATH environment variable.79- Or set ``g:clang_include_fixer_path`` in vimrc: ``let g:clang_include_fixer_path=path/to/clang-include-fixer``80 81You can customize the number of headers being shown by setting82``let g:clang_include_fixer_maximum_suggested_headers=5``83 84Customized settings in `.vimrc`:85 86- ``let g:clang_include_fixer_path = "clang-include-fixer"``87 88 Set clang-include-fixer binary file path.89 90- ``let g:clang_include_fixer_maximum_suggested_headers = 3``91 92 Set the maximum number of ``#includes`` to show. Default is 3.93 94- ``let g:clang_include_fixer_increment_num = 5``95 96 Set the increment number of #includes to show every time when pressing ``m``.97 Default is 5.98 99- ``let g:clang_include_fixer_jump_to_include = 0``100 101 Set to 1 if you want to jump to the new inserted ``#include`` line. Default is102 0.103 104- ``let g:clang_include_fixer_query_mode = 0``105 106 Set to 1 if you want to insert ``#include`` for the symbol under the cursor.107 Default is 0. Compared to normal mode, this mode won't parse the source file108 and only search the symbol from database, which is faster than normal mode.109 110See ``clang-include-fixer.py`` for more details.111 112Integrate with Emacs113--------------------114To run `clang-include-fixer` on a potentially unsaved buffer in Emacs.115Ensure that Emacs finds ``clang-include-fixer.el`` by adding the directory116containing the file to the ``load-path`` and requiring the `clang-include-fixer`117in your ``.emacs``:118 119.. code-block:: console120 121 (add-to-list 'load-path "path/to/llvm/source/clang-tools-extra/clang-include-fixer/tool/"122 (require 'clang-include-fixer)123 124Within Emacs the tool can be invoked with the command125``M-x clang-include-fixer``. This will insert the header that defines the126first undefined symbol; if there is more than one header that would define the127symbol, the user is prompted to select one.128 129To include the header that defines the symbol at point, run130``M-x clang-include-fixer-at-point``.131 132Make sure Emacs can find :program:`clang-include-fixer`:133 134- Either add the parent directory of :program:`clang-include-fixer` to the PATH135 environment variable, or customize the Emacs user option136 ``clang-include-fixer-executable`` to point to the file name of the program.137 138How it Works139============140 141To get the most information out of Clang at parse time,142:program:`clang-include-fixer` runs in tandem with the parse and receives143callbacks from Clang's semantic analysis. In particular it reuses the existing144support for typo corrections. Whenever Clang tries to correct a potential typo145it emits a callback to the include fixer which then looks for a corresponding146file. At this point rich lookup information is still available, which is not147available in the AST at a later stage.148 149The identifier that should be typo corrected is then sent to the database, if a150header file is returned it is added as an include directive at the top of the151file.152 153Currently :program:`clang-include-fixer` only inserts a single include at a154time to avoid getting caught in follow-up errors. If multiple `#include`155additions are desired the program can be rerun until a fix-point is reached.156