Visual Studio Projects

The build system automatically generates Visual Studio project files to aid with development, as part of a normal mach build from the command line.

You can find the solution file at $OBJDIR/msvs/mozilla.sln.

If you want to generate the project files before/without doing a full build, running ./mach configure && ./mach build-backend -b VisualStudio will do so.

Structure of Solution

The Visual Studio solution consists of hundreds of projects spanning thousands of files. To help with organization, the solution is divided into the following trees/folders:

Build Targets

This folder contains common build targets. The full project is used to perform a full build. The binaries project is used to build just binaries. The visual-studio project can be built to regenerate the Visual Studio project files.

Performing the clean action on any of these targets will clean the entire build output.


This folder contains common binaries that can be executed from within Visual Studio. If you are building the Firefox desktop application, the firefox project will launch firefox.exe. You probably want one of these set to your startup project.


This folder contains entries for each static library that is produced as part of the build. These roughly correspond to each directory in the tree containing C/C++. e.g. code from dom/base will be contained in the dom_base project.

These projects don’t do anything when built. If you build a project here, the binaries build target project is built.

Updating Project Files

Either re-running ./mach build or ./mach build-backend -b VisualStudio will update the Visual Studio files after the tree changes.

Moving Project Files Around

The produced Visual Studio solution and project files should be portable. If you want to move them to a non-default directory, they should continue to work from wherever they are. If they don’t, please file a bug.

Invoking mach through Visual Studio

It’s possible to run mach commands via Visual Studio. There is some light magic involved here.

Alongside the Visual Studio project files is a batch script named mach.bat. This batch script sets the environment variables present in your MozillaBuild development environment at the time of Visual Studio project generation and invokes mach inside an msys shell with the arguments specified to the batch script. This script essentially allows you to invoke mach commands inside the MozillaBuild environment without having to load MozillaBuild.

Projects currently utilize the mach build and mach clobber commands for building and cleaning the tree respectively. Note that running clobber deletes the Visual Studio project files, and running build recreates them. This might cause issues while Visual Studio is running. Thus a full rebuild is currently neither recommended, nor supported, but incremental builds should work.

The batch script does not limit its use: any mach command can be invoked. Developers may use this fact to add custom projects and commands that invoke other mach commands.