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16<h1>Open Clang Projects</h1>
17
18<p>Here are a few tasks that are available for newcomers to work on, depending
19on what your interests are.  This list is provided to generate ideas, it is not
20intended to be comprehensive.  Please ask on cfe-dev for more specifics or to
21verify that one of these isn't already completed. :)</p>
22
23<ul>
24<li><b>Undefined behavior checking</b>: CodeGen could
25insert runtime checks for all sorts of different undefined behaviors, from
26reading uninitialized variables, buffer overflows, and many other things.  This
27checking would be expensive, but the optimizers could eliminate many of the
28checks in some cases, and it would be very interesting to test code in this mode
29for certain crowds of people.  Because the inserted code is coming from clang,
30the "abort" message could be very detailed about exactly what went wrong.</li>
31
32<li><b>Improve target support</b>: The current target interfaces are heavily
33stubbed out and need to be implemented fully.  See the FIXME's in TargetInfo.
34Additionally, the actual target implementations (instances of TargetInfoImpl)
35also need to be completed.</li>
36
37<li><b>Implement an tool to generate code documentation</b>: Clang's
38library-based design allows it to be used by a variety of tools that reason
39about source code. One great application of Clang would be to build an
40auto-documentation system like doxygen that generates code documentation from
41source code. The advantage of using Clang for such a tool is that the tool would
42use the same preprocessor/parser/ASTs as the compiler itself, giving it a very
43rich understanding of the code.</li>
44
45<li><b>Use clang libraries to implement better versions of existing tools</b>:
46Clang is built as a set of libraries, which means that it is possible to
47implement capabilities similar to other source language tools, improving them
48in various ways.  Three examples are <a
49href="http://distcc.samba.org/">distcc</a>, the <a
50href="http://delta.tigris.org/">delta testcase reduction tool</a>, and the
51"indent" source reformatting tool.
52distcc can be improved to scale better and be more efficient.  Delta could be
53faster and more efficient at reducing C-family programs if built on the clang
54preprocessor, indent could do proper formatting for complex C++ features, and it
55would be straight-forward to extend a clang-based implementation to handle
56simple structural rules like those in <a
57href="http://llvm.org/docs/CodingStandards.html#hl_earlyexit">the LLVM coding
58standards</a>.</li>
59
60<li><b>Use clang libraries to extend Ragel with a JIT</b>: <a
61href="http://research.cs.queensu.ca/~thurston/ragel/">Ragel</a> is a state
62machine compiler that lets you embed C code into state machines and generate
63C code.  It would be relatively easy to turn this into a JIT compiler using
64LLVM.</li>
65
66<li><b>Self-testing using clang</b>: There are several neat ways to
67improve the quality of clang by self-testing. Some examples:
68<ul>
69  <li>Improve the reliability of AST printing and serialization by
70  ensuring that the AST produced by clang on an input doesn't change
71  when it is reparsed or unserialized.
72
73  <li>Improve parser reliability and error generation by automatically
74  or randomly changing the input checking that clang doesn't crash and
75  that it doesn't generate excessive errors for small input
76  changes. Manipulating the input at both the text and token levels is
77  likely to produce interesting test cases.
78</ul>
79</li>
80
81<li><b>Continue work on C++'11 support</b>:
82  C++'98 is feature complete, but there is still a lot of C++'11 features to
83  implement.  Please see the <a href="cxx_status.html">C++ status report
84  page</a> to find out what is missing.</li>
85</ul>
86
87<p>If you hit a bug with clang, it is very useful for us if you reduce the code
88that demonstrates the problem down to something small.  There are many ways to
89do this; ask on cfe-dev for advice.</p>
90
91<ul>
92<li><b>StringRef'ize APIs</b>: A thankless but incredibly useful project is
93StringRef'izing (converting to use <tt>llvm::StringRef</tt> instead of <tt>const
94char *</tt> or <tt>std::string</tt>) various clang interfaces. This generally
95simplifies the code and makes it more efficient.</li>
96
97<li><b>Universal Driver</b>: Clang is inherently a cross compiler. We would like
98to define a new model for cross compilation which provides a great user
99experience -- it should be easy to cross compile applications, install support
100for new architectures, access different compilers and tools, and be consistent
101across different platforms. See the <a href="UniversalDriver.html">Universal
102Driver</a> web page for more information.</li>
103
104<li><b>XML Representation of ASTs</b>: Clang maintains a rich Abstract Syntax Tree that describes the program. Clang could emit an XML document that describes the program, which others tools could consume rather than being tied directly to the Clang binary.The XML representation needs to meet several requirements:
105  <ul>
106    <li><i>General</i>, so that it's able to represent C/C++/Objective-C abstractly, and isn't tied to the specific internal ASTs that Clang uses.</li>
107    <li><i>Documented</i>, with appropriate Schema against which the output of Clang's XML formatter can be verified.</li>
108    <li><i>Stable</i> across Clang versions.</li>
109  </ul></li>
110</ul>
111
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