Visual Studio Code

General Knowledge

VSCode is a multi-platform open-source programming editor developed by Microsoft and volunteers. It has support for many programming languages using extensions.

For more general information on the VSCode project see repo.

C/C++ Features and Support

For C++ support we offer an out of the box configuration based on clangd.

Leveraging the clang toolchain compiler we now have support in the IDE for the following features:

1. Syntax highlighting

2. IntelliSense with comprehensive code completion and suggestion


3. Go-to definition and Go-to declaration


4. Find all references


5. Open type hierarchy


6. Rename symbol, all usages of the symbol will be renamed, including declaration, definition and references


7. Code formatting, based on clang-format that respects our coding standard using the .clang-format and .clang-format-ignore files. Format can be performed on an entire file or on a code selection


8. Inline parsing errors with limited auto-fix hints


9. Basic static-code analysis using clang-tidy and our list of enabled checkers. (This is still in progress not all checkers are supported by clangd)

Clangd-specific Commands

Clangd supports some commands that are specific to C/C++:


This command navigates from the currently open header file to its corresponding source file (if there is one), or vice versa.

This command can be invoked from the command menu (activated via F1), or using its keybinding of Alt+o (Alt+cmd+o on Mac). The keybinding can also be customized in Keyboard Shortcuts.

Generating Configuration

In order to build the configuration for VS Code simply run from the terminal:

./mach ide vscode

If VS Code is already open with a previous configuration generated, please make sure to restart VS Code otherwise the new configuration will not be used, and the compile_commands.json needed by clangd server will not be refreshed. This is a known bug in clangd-vscode extension

Useful preferences

When setting the preference

"editor.formatOnSave": true

you might find that this isn’t working on large source code files, but triggering formatting manually works. This is due to the default timeout for formatOnSave, which is quite short (750ms). You might want to increase this timeout, e.g.

"editor.formatOnSaveTimeout": 5000

Filing Bugs

Bugs should be filed in the Firefox Build System product under Developer Environment Integration, preferably blocking Bug 1662709.