1========
2Overview
3========
4
5Clang Tools are standalone command line (and potentially GUI) tools
6designed for use by C++ developers who are already using and enjoying
7Clang as their compiler. These tools provide developer-oriented
8functionality such as fast syntax checking, automatic formatting,
9refactoring, etc.
10
11Only a couple of the most basic and fundamental tools are kept in the
12primary Clang Subversion project. The rest of the tools are kept in a
13side-project so that developers who don't want or need to build them
14don't. If you want to get access to the extra Clang Tools repository,
15simply check it out into the tools tree of your Clang checkout and
16follow the usual process for building and working with a combined
17LLVM/Clang checkout:
18
19-  With Subversion:
20
21   -  ``cd llvm/tools/clang/tools``
22   -  ``svn co http://llvm.org/svn/llvm-project/clang-tools-extra/trunk extra``
23
24-  Or with Git:
25
26   -  ``cd llvm/tools/clang/tools``
27   -  ``git clone http://llvm.org/git/clang-tools-extra.git extra``
28
29This document describes a high-level overview of the organization of
30Clang Tools within the project as well as giving an introduction to some
31of the more important tools. However, it should be noted that this
32document is currently focused on Clang and Clang Tool developers, not on
33end users of these tools.
34
35Clang Tools Organization
36========================
37
38Clang Tools are CLI or GUI programs that are intended to be directly
39used by C++ developers. That is they are *not* primarily for use by
40Clang developers, although they are hopefully useful to C++ developers
41who happen to work on Clang, and we try to actively dogfood their
42functionality. They are developed in three components: the underlying
43infrastructure for building a standalone tool based on Clang, core
44shared logic used by many different tools in the form of refactoring and
45rewriting libraries, and the tools themselves.
46
47The underlying infrastructure for Clang Tools is the
48:doc:`LibTooling <LibTooling>` platform. See its documentation for much
49more detailed information about how this infrastructure works. The
50common refactoring and rewriting toolkit-style library is also part of
51LibTooling organizationally.
52
53A few Clang Tools are developed along side the core Clang libraries as
54examples and test cases of fundamental functionality. However, most of
55the tools are developed in a side repository to provide easy separation
56from the core libraries. We intentionally do not support public
57libraries in the side repository, as we want to carefully review and
58find good APIs for libraries as they are lifted out of a few tools and
59into the core Clang library set.
60
61Regardless of which repository Clang Tools' code resides in, the
62development process and practices for all Clang Tools are exactly those
63of Clang itself. They are entirely within the Clang *project*,
64regardless of the version control scheme.
65
66Core Clang Tools
67================
68
69The core set of Clang tools that are within the main repository are
70tools that very specifically complement, and allow use and testing of
71*Clang* specific functionality.
72
73``clang-check``
74---------------
75
76:doc:`ClangCheck` combines the LibTooling framework for running a
77Clang tool with the basic Clang diagnostics by syntax checking specific files
78in a fast, command line interface. It can also accept flags to re-display the
79diagnostics in different formats with different flags, suitable for use driving
80an IDE or editor. Furthermore, it can be used in fixit-mode to directly apply
81fixit-hints offered by clang. See :doc:`HowToSetupToolingForLLVM` for
82instructions on how to setup and used `clang-check`.
83
84``clang-format``
85~~~~~~~~~~~~~~~~
86
87Clang-format is both a :doc:`library <LibFormat>` and a :doc:`stand-alone tool
88<ClangFormat>` with the goal of automatically reformatting C++ sources files
89according to configurable style guides.  To do so, clang-format uses Clang's
90``Lexer`` to transform an input file into a token stream and then changes all
91the whitespace around those tokens.  The goal is for clang-format to serve both
92as a user tool (ideally with powerful IDE integrations) and as part of other
93refactoring tools, e.g. to do a reformatting of all the lines changed during a
94renaming.
95
96``cpp11-migrate``
97~~~~~~~~~~~~~~~~~
98``cpp11-migrate`` migrates C++ code to use C++11 features where appropriate.
99Currently it can:
100
101* convert loops to range-based for loops;
102
103* convert null pointer constants (like ``NULL`` or ``0``) to C++11 ``nullptr``;
104
105* replace the type specifier in variable declarations with the ``auto`` type specifier;
106
107* add the ``override`` specifier to applicable member functions.
108
109Extra Clang Tools
110=================
111
112As various categories of Clang Tools are added to the extra repository,
113they'll be tracked here. The focus of this documentation is on the scope
114and features of the tools for other tool developers; each tool should
115provide its own user-focused documentation.
116
117Ideas for new Tools
118===================
119
120* C++ cast conversion tool.  Will convert C-style casts (``(type) value``) to
121  appropriate C++ cast (``static_cast``, ``const_cast`` or
122  ``reinterpret_cast``).
123* Non-member ``begin()`` and ``end()`` conversion tool.  Will convert
124  ``foo.begin()`` into ``begin(foo)`` and similarly for ``end()``, where
125  ``foo`` is a standard container.  We could also detect similar patterns for
126  arrays.
127* ``make_shared`` / ``make_unique`` conversion.  Part of this transformation
128  can be incorporated into the ``auto`` transformation.  Will convert
129
130  .. code-block:: c++
131
132    std::shared_ptr<Foo> sp(new Foo);
133    std::unique_ptr<Foo> up(new Foo);
134
135    func(std::shared_ptr<Foo>(new Foo), bar());
136
137  into:
138
139  .. code-block:: c++
140
141    auto sp = std::make_shared<Foo>();
142    auto up = std::make_unique<Foo>(); // In C++14 mode.
143
144    // This also affects correctness.  For the cases where bar() throws,
145    // make_shared() is safe and the original code may leak.
146    func(std::make_shared<Foo>(), bar());
147
148* ``tr1`` removal tool.  Will migrate source code from using TR1 library
149  features to C++11 library.  For example:
150
151  .. code-block:: c++
152
153    #include <tr1/unordered_map>
154    int main()
155    {
156        std::tr1::unordered_map <int, int> ma;
157        std::cout << ma.size () << std::endl;
158        return 0;
159    }
160
161  should be rewritten to:
162
163  .. code-block:: c++
164
165    #include <unordered_map>
166    int main()
167    {
168        std::unordered_map <int, int> ma;
169        std::cout << ma.size () << std::endl;
170        return 0;
171    }
172
173* A tool to remove ``auto``.  Will convert ``auto`` to an explicit type or add
174  comments with deduced types.  The motivation is that there are developers
175  that don't want to use ``auto`` because they are afraid that they might lose
176  control over their code.
177
178* C++14: less verbose operator function objects (`N3421
179  <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3421.htm>`_).
180  For example:
181
182  .. code-block:: c++
183
184    sort(v.begin(), v.end(), greater<ValueType>());
185
186  should be rewritten to:
187
188  .. code-block:: c++
189
190    sort(v.begin(), v.end(), greater<>());
191
192