Nick Desaulniers

The enemy's gate is down

Additional C/C++ Tooling

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21st Century C by Ben Klemens was a great read. It had a section with an intro to autotools, git, and gdb. There are a few other useful tools that came to mind that I’ve used when working with C and C++ codebases. These tools are a great way to start contributing to Open Source C & C++ codebases; running these tools on the code or adding them to the codebases. A lot of these favor command line, open source utilities. See how many you are familiar with!

Build Tools


The first tool I’d like to take a look at is CMake. CMake is yet another build tool; I realize how contentious it is to even discuss one of the many. From my experience working with Emscripten, we recommend the use of CMake for people writing portable C/C++ programs. CMake is able to emit Makefiles for unixes, project files for Xcode on OSX, and project files for Visual Studio on Windows. There are also a few other “generators” that you can use.

I’ve been really impressed with CMake’s modules for finding dependencies and another for fetching and building external dependencies. I think C++ needs a package manager badly, and I think CMake would be a solid foundation for one.

The syntax isn’t the greatest, but when I wanted to try to build one of my C++ projects on Windows which I know nothing about developing on, I was able to install CMake and Visual Studio and get my project building. If you can build your code on one platform, it will usually build on the others.

If you’re not worried about writing cross platform C/C++, maybe CMake is not worth the effort, but I find it useful. I wrestle with the syntax sometimes, but documentation is not bad and it’s something you deal with early on in the development of a project and hopefully never have to touch again (how I wish that were true).

Code Formatters


Another contentious point of concern amongst developers is code style. Big companies with lots of C++ code have documents explaining their stylistic choices. Don’t waste another hour of your life arguing about something that really doesn’t matter. ClangFormat will help you codify your style and format your code for you to match the style. Simply write the code however you want, and run the formatter on it before commiting it.

It can also emit a .clang-format file that you can commit and clang-format will automatically look for that file and use the rules codified there.


Flint / Flint++

Flint is a C++ linter in use at Facebook. Since it moved from being implemented in C++ to D, I’ve had issues building it. I’ve had better luck with a fork that’s pure C++ without any of the third party dependencies Flint originally had, called Flint++. While not quite full-on static analyzers, both can be used for finding potential issues in your code ahead of time. Linters can look at individual files in isolation; you don’t have to wait for long recompiles like you would with a static analyzer.

Static Analyzers


Scan-build is a static analyzer for C and C++ code. You build your code “through” it, then use the sibling tool scan-view to see the results. Scan-view will emit and open an html file that shows a list of the errors it detected. It will insert hyperlinks into the resulting document that step you through how certain conditions could lead to a null pointer dereference, for example. You can also save and share those html files with others in the project. Static analyzers will help you catch bugs at compile time before you run the code.

Runtime Sanitizers

ASan and UBSan

Clang’s Address (ASan) and Undefined Behavior (UBSan) sanitizers are simply compiler flags that can be used to detect errors at runtime. ASan and UBSan two of the more popular tools, but there are actually a ton and more being implemented. See the list here. These sanitizers will catch bugs at runtime, so you’ll have to run the code to notice any violations, at variable runtime performance costs per sanitizer. ASan and TSan (Thread Sanitizer) made it into gcc4.8 and UBSan is in gcc4.9.

Header Analysis

Include What You Use

Include What You Use (IWYU) helps you find unused or unnecessary #include preprocessor directives. It should be obvious how this can help improve compile times. IWYU can also help cut down on recompiles by recommending forward declarations under certain conditions. I look forward to the C++ module proposal being adopted, but until then this tool can help you spot cruft that can be removed.

Rapid Recompiles


ccache greatly improves recompile times by caching the results of parts of the compilation process. I use when building Firefox, and it saves a great deal of time.


distcc is a distributed build system. Some folks at Mozilla speed up their Firefox builds with it.

Memory Leak Detectors


Valgrind has a suite of tools, my favorite being memcheck for finding memory leaks. Unfortunately, it doesn’t seem to work on OSX since 10.10. This page referring to ASan seems to indicate that it can do everything Valgrind’s Memcheck can, at less of a runtime performance cost, but I’m not sure how true this is exactly.


A much more primitive tool for finding leaks from the command line, BSD’s have leaks.

MallocStackLogging=1 ./a.out
leaks a.out



Perf, and Brendan Gregg’s tools for emitting SVG flamegraphs from the output are helpful for finding where time is spent in a program. In fact, there are numerous perfomance analysis tools that are Linux specific. My recommendation is spend some time on Brendan Gregg’s blog.


OSX doesn’t have the same tooling as Linux, but DTrace was ported to it. I’ve used it to find sampling profiles of my code before. Again, Brendan Gregg’s blog is a good resource; there are some fantastic DTrace one liners.



lldb is analogous to gdb. I can’t say I have enough experience with LLDB and GDB to note the difference between the two, but LLDB did show the relative statements forward and back from the current statement by default. I’m informed by my friends/mortal enemies using emacs that this is less of an issue when using emacs/gdb in combination.


American Fuzzy Lop

American Fuzzy Lop (AFL) is a neat program that performs fuzzing on programs that take inputs from files and repeatedly runs the program, modifies the input trying to get full code coverage, and tries to find crashes. It’s been getting lots of attention lately, and while I haven’t used it myself yet, it seems like a very powerful tool. Mozilla employs the use of fuzzers on their JavaScript engine, for instance (not AFL, but one developed in house).



If you really need to make sure the higher level code you’re writing is getting translated into the assembly your expecting, gobjdump -S will intermix the emitted binary’s disassembled assembly and the source code. This was used extensively while developing my Brainfuck JIT.


Hopefully you learned of some useful tools that you should know about when working with C or C++. What did I miss?