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I have been using a really cool little utility that I’d like to share with the 3 people who read my blog: The Clang Static Analyzer.  This little command-line utility is pretty damned slick.  What it does is it parses your code and identifies possible memory leaks and logic errors.  It’s a bit of a pain to get running, but once it’s in place, it’s VERY helpful.  I should mention that it works best for Objective-C and is built with Mac OS X and Xcode in mind.  Still, if you are working on a Mac or been having memory issues on the iPhone project, ClangSA is for you!  So let’s get started:

Go here Clang Static Analyzer Page and download the Latest Build, which should be near the top.  Once that has downloaded, unzip it and rename it to something like ClangSA or whatever you want.  I will be using ClangSA for the purposes of this tutorial.  Put the newly named folder wherever you like, I would recommend your Developer folder.

Alright, so now you have the Clang build on your desktop.  Where to from here?  Well, we could just use it as is, but this means you will have to cd into your Desktop and use the analyzer’s explicit path every time you want to use it.  Instead, we are going to write a shell script (*gasp* command line?!) to make the analyzer available to you from anywhere.  I use tcsh, but we will build a script for both tcsh and bash, just for fun.

Open your Terminal application.  From your ~ directory (Home) find your /bin folder.  If one does not exist, create one with: mkdir ~/bin.

Next: cd ~/bin.  Now that we are inside the bin folder, we are going to make a symbolic link to the analyzer.  To do this type: ln -s <Location of your ClanSA directory>/scan-build.  *WARNING* moving your ClangSA directory after making this link will break it.

We now have a link to the scan-build command for the analyzer.  This command is run on your code to execute the analysis.  For this next part you will need to check your shell.  Type: echo $SHELL.  If the result of that is tcsh, read on.  If it is bash, go down to the BASH section.


Navigate back home with: cd ~.  Next, type: emacs .cshrc.  If there is already contents in this file, add the following to the end of the file.  Type in the following:

set path = (~/bin $path)

Right.  This makes ~/bin part of the command-line’s search path for global commands.  This will allow us to invoke scan-build from anywhere, which is VERY handy.  Save the file with Ctrl-x Crtl-s.  Then exit emacs with Ctrl-x Ctrl-c.  After the bash section is more information, so skip down there and check it out.


Navigate to your home directory with: cd ~.  Then open up the editor with: emacs .profile.  If text already exists in this script, just put the following at the bottom.  Enter the following text into the script:

export PATH=~/bin:$PATH

That’s it!  Save the file with Ctrl-x Ctrl-s.  Then exit emacs with Ctrl-x Ctrl-c.  This allows us to invoke scan-build from anywhere, which is VERY handy.


If you haven’t read the Clang site yet, I’ll reiterate what it says here as well as explain how to use it.  Clang is best used on a project that has not been recently built.  So before using the ClangSA, open your Xcode project and do a Clean.  This will get rid of temp files and mark all of the source as unbuilt, which is necessary for the analyzer to work.  Once you have cleaned the project, open up the Terminal again.

Cd into your project folder.  If you do an ls, you should see all of your source files and the project file.  From inside this directory, type the following command:

scan-build -k -V xcodebuild -configuration Debug

This calls the scan-build command that we made global in the scripts above.  It should start spewing out a lot of information, but none of it is really what you are looking for.  When it’s done, it should open up a browser window with bug and memory information.  Oh, yeah, you always want to use the Debug configuration.  Apparently, Clang has a nasty habit of modifying and parsing build configurations, so it’s best to break Debug should that happen.

If you are building an iPhone project you will need to include your sdk.  To do this, type in the following line:

scan-build -k -V xcodebuild -configuration Debug -sdk iphonesimulator<SDK version, such as 3.0>

And that’s it!  The analyzer is not perfect, but DAMN is it ever helpful.  And it’s also pretty smart, so work with it to improve your code.  I really hope that Apple makes this an integral part of Xcode in the future (which is the current rumor).  Code away!


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