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| <h1>Clang Static Analyzer</h1> |
| |
| <p>The Clang Static Analyzer is a source code analysis tool that finds bugs in |
| C, C++, and Objective-C programs.</p> |
| |
| <p>Currently it can be run either from the <a href="command-line.html">command |
| line</a> or if you use macOS then <a href="xcode.html">within Xcode</a>. When |
| invoked from the command line, it is intended to be run in tandem with a build |
| of a codebase.</p> |
| |
| <p>The analyzer is 100% open source and is part of the <a |
| href="https://clang.llvm.org">Clang</a> project. Like the rest of Clang, the |
| analyzer is implemented as a C++ library that can be used by other tools and |
| applications.</p> |
| |
| <h2>Download</h2> |
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| <h3 style="margin:0px;padding:0px">Mac OS X</h3> |
| <ul> |
| <li>Latest build (10.8+):<br> |
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| <li><a href="/release_notes.html">Release notes</a></li> |
| <li>This build can be used both from the command line and from within Xcode</li> |
| <li><a href="/installation.html">Installation</a> and <a href="/scan-build.html">usage</a></li> |
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| <h3 style="margin:0px;padding:0px">Other Platforms</h3> |
| <p>For other platforms, please follow the instructions for <a |
| href="/installation#OtherPlatforms">building the analyzer</a> from |
| source code.<p> |
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| <a href="images/analyzer_xcode.png"><img src="images/analyzer_xcode.png" width="450" alt="analyzer in xcode"></a> |
| <div style="text-align:center"><b>Viewing static analyzer results in Xcode</b></div> |
| <a href="images/analyzer_html.png"><img src="images/analyzer_html.png" width="450" alt="analyzer in browser"></a> |
| <div style="text-align:center"><b>Viewing static analyzer results in a web browser</b></div> |
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| <h2 id="StaticAnalysis">What is Static Analysis?</h2> |
| |
| <p>The term "static analysis" is conflated, but here we use it to mean |
| a collection of algorithms and techniques used to analyze source code in order |
| to automatically find bugs. The idea is similar in spirit to compiler warnings |
| (which can be useful for finding coding errors) but to take that idea a step |
| further and find bugs that are traditionally found using run-time debugging |
| techniques such as testing.</p> |
| |
| <p>Static analysis bug-finding tools have evolved over the last several decades |
| from basic syntactic checkers to those that find deep bugs by reasoning about |
| the semantics of code. The goal of the Clang Static Analyzer is to provide a |
| industrial-quality static analysis framework for analyzing C, C++, and |
| Objective-C programs that is freely available, extensible, and has a high quality of implementation.</p> |
| |
| <h3 id="Clang">Part of Clang and LLVM</h3> |
| |
| <p>As its name implies, the Clang Static Analyzer is built on top of <a |
| href="https://clang.llvm.org">Clang</a> and <a href="https://llvm.org">LLVM</a>. |
| Strictly speaking, the analyzer is part of Clang, as Clang consists of a set of |
| reusable C++ libraries for building powerful source-level tools. The static |
| analysis engine used by the Clang Static Analyzer is a Clang library, and has |
| the capability to be reused in different contexts and by different clients.</p> |
| |
| <h2>Important Points to Consider</h2> |
| |
| <p>While we believe that the static analyzer is already very useful for finding |
| bugs, we ask you to bear in mind a few points when using it.</p> |
| |
| <h3>Work-in-Progress</h3> |
| |
| <p>The analyzer is a continuous work-in-progress. There are many planned |
| enhancements to improve both the precision and scope of its analysis algorithms |
| as well as the kinds of bugs it will find. While there are fundamental |
| limitations to what static analysis can do, we have a long way to go before |
| hitting that wall.</p> |
| |
| <h3>Slower than Compilation</h3> |
| |
| <p>Operationally, using static analysis to |
| automatically find deep program bugs is about trading CPU time for the hardening |
| of code. Because of the deep analysis performed by state-of-the-art static |
| analysis tools, static analysis can be much slower than compilation.</p> |
| |
| <p>While the Clang Static Analyzer is being designed to be as fast and |
| light-weight as possible, please do not expect it to be as fast as compiling a |
| program (even with optimizations enabled). Some of the algorithms needed to find |
| bugs require in the worst case exponential time.</p> |
| |
| <p>The Clang Static Analyzer runs in a reasonable amount of time by both |
| bounding the amount of checking work it will do as well as using clever |
| algorithms to reduce the amount of work it must do to find bugs.</p> |
| |
| <h3>False Positives</h3> |
| |
| <p>Static analysis is not perfect. It can falsely flag bugs in a program where |
| the code behaves correctly. Because some code checks require more analysis |
| precision than others, the frequency of false positives can vary widely between |
| different checks. Our long-term goal is to have the analyzer have a low false |
| positive rate for most code on all checks.</p> |
| |
| <p>Please help us in this endeavor by <a href="filing_bugs.html">reporting false |
| positives</a>. False positives cannot be addressed unless we know about |
| them.</p> |
| |
| <h3>More Checks</h3> |
| |
| <p>Static analysis is not magic; a static analyzer can only find bugs that it |
| has been specifically engineered to find. If there are specific kinds of bugs |
| you would like the Clang Static Analyzer to find, please feel free to |
| file <a href="filing_bugs.html">feature requests</a> or contribute your own |
| patches.</p> |
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