This guide describes how to edit the Drake codebase using VS Code.

If you have tips that would help out other developers, drop us a line and we can add them here!

Setting up VS Code

There is nothing really special to do. Be sure you’ve installed the C/C++ extension pack from Microsoft.

C++ paths

Because VS Code wants to locate all included headers, but Bazel does not provide those headers in a single consistent location, it is common to get “red squiggles” for included headers, particularly for externals like LCM. So far this does not seem to be avoidable; the "C_Cpp.errorSquiggles": "enabledIfIncludesResolve" setting does not work to solve this problem.

C++ code formatting

The Visual Studio docs on code formatting work well. Take note of “Format Document”, “Format Selection”, “Format on save”, and “Format on type”.

In the VS Code Options configuration, check that the option for C_Cpp: Clang_format_path is set to Drake’s preferred value /path/to/drake/bazel-bin/tools/lint/clang-format.

C++ code semantic analysis / autocompletion

VScode relies on the language server clangd and the json file compile_commands.json for code semantic analysis / autocompletion. To enable this feature, take the following steps

Install clangd on your system. On Ubuntu, do
```
$ sudo apt install clangd
```
On mac, do
```
brew install llvm
```
In VSCode, add clangd extension. If you have IntelliSense, disable it through
```
// .vscode/settings.json
{
  "C_Cpp.intelliSenseEngine": "disabled"
}
```
To generate compile_commands.json file, take the following steps
- Checkout this branch of bazel-compile-commands-extractor (the upstream version doesn’t work with Drake)
```
 $ git clone git@github.com:hongkai-dai/bazel-compile-commands-extractor.git
 $ git checkout enable_drake
```
- Then add this to your drake/user.bazelrc
```
 common --inject_repository=hedron_compile_commands=PATH_TO_BAZEL_COMPILE_COMMANDS_EXTRACTOR
```
  where PATH_TO_BAZEL_COMPILE_COMMANDS_EXTRACTOR is the directory where you checked out bazel-compile-commands-extractor.
- In drake folder, run
```
 $ bazel run @hedron_compile_commands//:refresh_all
```
  You should see a compile_commands.json file in your drake folder. Note: this command might take a while (like 5 mins) to run. You probably will see some error messages like
```
 bazel-out/k8-opt/bin/external/+internal_repositories+fcl_internal/drake_hdr/fcl/common/types.h:130:27: error: missing binary operator before token "("
 130 | #if EIGEN_VERSION_AT_LEAST(3,2,9)
```
  you can ignore these error messages.
In VSCode, you should see that you can go to the definition of any C++ object, and the autocompletion is semantic-based.
Everytime Drake Bazel build files (including BUILD.bazel) are changed, you will need to rerun bazel run @hedron_compile_commands//:refresh_all to update the compilation_commands.json file.

These instructions are adapted from Hedronvision’s bazel-compile-commands-extractor project.