path: root/chromium/docs/vscode.md

# Visual Studio Code Dev

Visual Studio Code is a free, lightweight and powerful code editor for Windows,
Mac and Linux, based on Electron/Chromium. It has built-in support for
JavaScript, TypeScript and Node.js and a rich extension ecosystem that adds
intellisense, debugging, syntax highlighting etc. for many languages (C++,
Python, Go, Java). It works without too much setup. Get started
[here](https://code.visualstudio.com/docs).

It is NOT a full-fledged IDE like Visual Studio. The two are completely
separate products. The only commonality with Visual Studio is that both are
from Microsoft.

Here's what works well:

*   Editing code works well especially when you get used to the [keyboard
    shortcuts](https://code.visualstudio.com/docs/customization/keybindings).
    VS Code is very responsive and can handle even big code bases like Chromium.
*   Git integration is a blast. Built-in side-by-side view, local commit and
    even extensions for
    [history](https://marketplace.visualstudio.com/items?itemName=donjayamanne.githistory)
    and
    [blame view](https://marketplace.visualstudio.com/items?itemName=ryu1kn.annotator).
*   [Debugging](https://code.visualstudio.com/Docs/editor/debugging) works
    well, even though startup times can be fairly high (~40 seconds with
    gdb on Linux, much lower on Windows). You can step through code, inspect
    variables, view call stacks for multiple threads etc.
    *   For more information on debugging Python code, see [here](vscode_python.md).
*   Opening files and searching solution-wide works well now after having
    problems in earlier versions.
*   Building works well. Build tools are easy to integrate. Warnings and errors
    are displayed on a separate page and you can click to jump to the
    corresponding line of code.
*   VSCode Remote, which allows you to edit remotely-hosted code, and even run
    computationally expensive plugins like vscode-clangd on the remote
    server/workstation (see the [Remote section](#Remote)). Great for working-
    from-home. (Googlers: See [go/vscode-remote](http://go/vscode-remote)].)

[TOC]

## Updating This Page

Please keep this doc up-to-date. VS Code is still in active development and
subject to changes. This doc is checked into the Chromium git repo, so if you
make changes, read the [documentation
guidelines](documentation_guidelines.md)
and [submit a change list](contributing.md).

All file paths and commands have been tested on Linux. Windows and Mac might
require a slightly different setup (e.g. `Ctrl` -> `Cmd`). Please update this
page accordingly.

## Setup

### Installation

Follow the steps on https://code.visualstudio.com/docs/setup/setup-overview. To
run it on Linux, just navigate to Chromium's `src` folder and type `code .` in a
terminal. The argument to `code` is the base directory of the workspace. VS
Code does not require project or solution files. However, it does store
workspace settings in a `.vscode` folder in your base directory.

### Fixes for Known Issues

#### Git on Windows

If you only have the `depot_tools` Git installed on your machine, even though it
is in your PATH, VS Code will ignore it as it seems to be looking for `git.exe`.
You will have to add the following to your settings in order for the Git
integration to work:

```json
{
  "git.path": "C:\\src\\depot_tools\\git.bat"
}
```

### Useful Extensions

Up to now, you have a basic version of VS Code without much language support.
Next, we will install some useful extensions. Jump to the extensions window
(`Ctrl+Shift+X`) and install these extensions, you will most likely use them
every day:

*   ***C/C++*** -
    Code formatting, debugging, Intellisense. Enables the use of clang-format
    (via the `C_Cpp.clang_format_path` setting) and format-on-save (via the
    `editor.formatOnSave` setting).
*   ***Python*** -
    Linting, intellisense, code formatting, refactoring, debugging, snippets.
*   ***Toggle Header/Source*** -
    Toggles between .cc and .h with `F4`. The C/C++ extension supports this as
    well through `Alt+O` but sometimes chooses the wrong file when there are
    multiple files in the workspace that have the same name.
*   ***Protobuf support*** -
    Syntax highlighting for .proto files.
*   [***Mojom IDL support***](https://github.com/GoogleChromeLabs/mojom-language-support) -
    Syntax highlighting and a
    [language server](https://microsoft.github.io/language-server-protocol/)
    for .mojom files. This isn't available on the VS Code marketplace for now.
    You need to install it manually.
*   ***vscode-clangd*** -
    If you do not plan to use VSCode for debugging, vscode-clangd is a great
    alternative to C/C++ IntelliSense. It knows about how to compile Chromium,
    enabling it to provide smarter autocomplete than C/C++ IntelliSense as well
    as allowing you to jump from functions to their definitions. See
    [clangd.md](clangd.md) for setup instructions.
    If you need to debug, enable C/C++ extension but set "C_Cpp: Intelli Sense Engine" to disabled,
    and restart VSCode.
*   ***Rewrap*** -
    Wrap lines at 80 characters with `Alt+Q`.
*   ***Remote*** -
    Remotely connect to your workstation through SSH using your laptop. See the
    [Remote](#Remote) section for more information about how to set this up.

The following extensions might be useful for you as well:

*   ***Annotator*** -
    Git blame view.
*   ***Git History (git log)*** -
    Git history view.
*   ***chromium-codesearch*** -
    Mac and Linux only: adds ability to open the current line in [Chromium Code
    Search](https://cs.chromium.org/). All other functionality is deprecated, so
    currently only of limited usefulness.
*   ***change-case*** -
    Quickly change the case of the current selection or current word.
*   ***Instant Markdown*** -
    Instant markdown (.md) preview in your browser as you type. This document
    was written with this extension!

Also be sure to take a look at the
[VS Code marketplace](https://marketplace.visualstudio.com/VSCode) to check out
other useful extensions.

### Color Scheme
Press `Ctrl+Shift+P, color, Enter` to pick a color scheme for the editor. There
are also tons of [color schemes available for download on the
marketplace](https://marketplace.visualstudio.com/search?target=VSCode&category=Themes&sortBy=Downloads).

### Usage Tips
*   `Ctrl+P` opens a search box to find and open a file.
*   `F1` or `Ctrl+Shift+P` opens a search box to find a command (e.g. Tasks: Run
    Task).
*   `Ctrl+K, Ctrl+S` opens the key bindings editor.
*   ``Ctrl+` `` toggles the built-in terminal.
*   `Ctrl+Shift+M` toggles the problems view (linter warnings, compile errors
    and warnings). You'll swicth a lot between terminal and problem view during
    compilation.
*   `Alt+O` switches between the source/header file.
*   `Ctrl+G` jumps to a line.
*   `F12` jumps to the definition of the symbol at the cursor (also available on
    right-click context menu).
*   `Shift+F12` or `F1, CodeSearchReferences, Return` shows all references of
    the symbol at the cursor.
*   `F1, CodeSearchOpen, Return` opens the current file in Code Search.
*   `Ctrl+D` selects the word at the cursor. Pressing it multiple times
    multi-selects the next occurrences, so typing in one types in all of them,
    and `Ctrl+U` deselects the last occurrence.
*   `Ctrl+K, Z` enters Zen Mode, a fullscreen editing mode with nothing but the
    current editor visible.
*   `Ctrl+X` without anything selected cuts the current line. `Ctrl+V` pastes
    the line.

### Java/Android Support
To get Java support in VS Code, you'll need to install the
'Java Extension Pack' extension, but you'll want to immediately uninstall or
disable the Maven for Java extension so it stops nagging you as we won't need
it.

#### Setting up code completion/reference finding/etc.
You'll need to generate a placeholder .classpath file and locate it. In order
to generate it, right click on any Java source folder in the left panel and
choose "Add folder to java source path". Its location will depend on whether
you're doing local or remote development. Local path on linux will look
something like:

`~/.vscode/data/User/workspaceStorage/<hash>/redhat.java/jdt_ws/<project>/.classpath`

You might find multiple folders when looking for `<project>`. Choose anything except
`jdt.ls-java-project`. If you only see `jdt.ls-java-project`, try using the
"Add folder to java source path" option again.

If doing remote development, the file will be under `~/.vscode-server/` on your
remote machine.

You'll need to replace all of the contents of that file with the contents of
`tools/android/eclipse/.classpath` (external) or
`clank/development/ide/eclipse/.classpath` (generated by gclient runhooks for
Chrome developers), and then replace some paths as vscode interprets some paths
differently from eclipse.
*   Replace: `kind="src" path="` with `kind="src" path="_/`
    * eg. `<classpathentry kind="src" path="_/android_webview/glue/java/src"/>`
*   Replace: `kind="lib" path="../src` with `kind="lib" path="_`
    * eg.
`<classpathentry kind="lib" path="_/out/Debug/lib.java/base/base_java.jar"/>`
*   Remove all nested paths (or exclude them from their parents). At time of
writing:
    * `third_party/android_protobuf/src/java/src/main/java`
    * `third_party/junit/src/src/main/java`

Also, make sure
`export ANDROID_HOME=/usr/local/google/home/{your_ldap}/Android/Sdk` is in the
remote machine's `~/.bashrc`.

Then restart vscode, open a Java file, and wait for a bit.

Debugging tips:
*   Right clicking on a folder in vscode and clicking "Add folder to java source
path" will error if there are syntax problems with your classpath. (Don't use
this actually add new paths to your classpath as it won't work correctly)
    * If there are no syntax errors, ensure the correct .classpath file is being
    used by seeing if the folder was actually added to the .classpath file you
    edited.

## Setup For Chromium

VS Code is configured via JSON files. This paragraph contains JSON configuration
files that are useful for Chromium development, in particular. See [VS Code
documentation](https://code.visualstudio.com/docs/customization/overview) for an
introduction to VS Code customization.

### Workspace Settings
Open the file [//tools/vscode/settings.json5](/tools/vscode/settings.json5),
and check out the default settings there. Feel free to commit added or removed
settings to enable better team development, or change settings locally to suit
personal preference. Remember to replace `<full_path_to_your_home>`! To use
these settings wholesale, enter the following commands into your terminal while
at the src directory:
```
$ mkdir .vscode/
$ cp tools/vscode/settings.json5 .vscode/settings.json
```

Note: these settings assume that the workspace folder (the root folder displayed
in the Explorer tab) is Chromium's `src/` directory. If this is not the case,
replace any references to ${workspaceFolder} with the path to your `src/`.

### Tasks
Next, we'll tell VS Code how to compile our code, run tests, and to read
warnings and errors from the build output. Open the file
[//tools/vscode/tasks.json5](/tools/vscode/tasks.json5). This will provide tasks
to do basic things. You might have to adjust the commands to your situation and
needs. To use these settings wholesale, enter the following command into your
terminal:
```
$ cp tools/vscode/tasks.json5 .vscode/tasks.json
```

### Launch Commands
Launch commands are the equivalent of `F5` in Visual Studio: They launch some
program or a debugger. Optionally, they can run some task defined in
`tasks.json`. Launch commands can be run from the debug view (`Ctrl+Shift+D`).
Open the file at [//tools/vscode/launch.json5](/tools/vscode/launch.json5) and
adjust the example launch commands to your situation and needs (e.g., the value
of "type" needs adjustment for Windows). To use these settings wholesale, enter
the following command into your terminal:
```
$ cp tools/vscode/launch.json5 .vscode/launch.json
```

### Key Bindings
To edit key bindings, press `Ctrl+K, Ctrl+S`. You'll see the defaults on the
left and your overrides on the right stored in the file `keybindings.json`. To
change a key binding, copy the corresponding key binding to the right. It's
fairly self-explanatory.

You can bind any command to a key, even commands specified by extensions like
`CodeSearchOpen`. For instance, to bind `CodeSearchOpen` to `F2` to , simply add
`{ "key": "F2", "command": "cs.open" },`.
Note that the command title `CodeSearchOpen` won't work. You have to get the
actual command name from the [package.json
file](https://github.com/chaopeng/vscode-chromium-codesearch/blob/master/package.json)
of the extension.

If you are used to other editors, you can also install your favorite keymap.
For instance, to install eclipse keymaps, install the
`vscode-eclipse-keybindings` extension. More keymaps can be found
[in the marketplace](https://marketplace.visualstudio.com/search?target=vscode&category=Keymaps).

Some key bindings that are likely to be useful for you are available at
[//tools/vscode/keybindings.json5](/tools/vscode/keybindings.json5). Please
take a look and adjust them to your situation and needs. To use these settings
wholesale, enter the following command into your terminal:
```
$ cp tools/vscode/keybindings.json5 .vscode/keybindings.json
```

### Remote
VSCode now has a
[Remote](https://code.visualstudio.com/docs/remote/remote-overview) framework
that allows you to use VSCode on your laptop while your code is hosted
elsewhere. This really shines when used in conjunction with the vscode-clangd plugin,
which allows clangd to run remotely as well.

To get this to run, install the Remote pack extension, and then make sure your
ssh config file has your remote connection:

`~/.ssh/config`:
```
Host my-connection
  HostName my-remote-host.corp.company.com
```

VSCode will then list this connection in the 'Remote Explorer' section on the
left. To launch VSCode with this connection, click on the '+window' icon next
to the listed hostname. It has you choose a folder - use the 'src' folder root.
This will open a new VSCode window in 'Remote' mode. ***Now you can install
extensions specifically for your remote connection, like vscode-clangd, etc.***

#### Chromebooks

For Googlers, [here](http://go/vscode/remote_development_via_web) are
Google-specific instructions for setting up remote development on chromebooks
without using Crostini.

#### Windows & SSH

VSCode remote tools requires 'sshd' which isn't installed on Windows by default.

For Googlers, sshd should already be installed on your workstation, and VSCode
should work remotely if you followed the setup instructions at
[go/building-chrome-win](http://go/building-chrome-win). If you are still having
problems, please refer to
[go/vscode-remote#windows](http://go/vscode-remote#windows).

Non-Googlers may follow may follow Microsoft's instructions for
[installing the OpenSSH server](https://docs.microsoft.com/en-us/windows-server/administration/openssh/openssh_install_firstuse).
VSCode should work remotely after following this step.

### Snippets
There are some useful snippets provided in
[//tools/vscode/cpp.json5](/tools/vscode/cpp.json5).

You can either install them in your user profile (path may vary depending on the
platform):
```
$ cp tools/vscode/cpp.json5 ~/.config/Code/User/snippets/cpp.json
```

Or install them as project snippets after installing the [Project
Snippets](https://marketplace.visualstudio.com/items?itemName=rebornix.project-snippets)
extension:
```
$ cp tools/vscode/cpp.json5 .vscode/snippets/cpp.json
```

### Tips

#### The `out` folder
Automatically generated code is put into a subfolder of out/, which means that
these files are ignored by VS Code (see files.exclude above) and cannot be
opened e.g. from quick-open (`Ctrl+P`).
As of version 1.21, VS Code does not support negated glob commands, but you can
define a set of exclude pattern to include only out/Debug/gen:
```
"files.exclude": {
  // Ignore build output folders. Except out/Debug/gen/
  "out/[^D]*/": true,
  "out/Debug/[^g]*": true,
  "out/Debug/g[^e]*": true,
  "out_*/**": true,
},
```

Once it does, you can use
```
"!out/Debug/gen/**": true
```
in files.exclude instead of the symlink.

#### Using VS Code as git editor
Add `[core] editor = "code --wait"` to your `~/.gitconfig` file in order to use
VS Code as editor for git commit messages etc. Note that the editor starts up
significantly slower than nano or vim. To use VS Code as merge tool, add
`[merge] tool = code`.

#### Task Names
Note that we named the tasks `1-build_chrome_debug`, `2-build_chrome_release`
etc. This allows you to quickly execute tasks by pressing their number:
Press `Ctrl+P` and enter `task <n>`, where `<n>` is the number of the task. You
can also create a keyboard shortcut for running a task. `File > Preferences >
Keyboard Shortcuts` and add `{ "key": "ctrl+r", "command":
"workbench.action.tasks.runTask", "when": "!inDebugMode" }`. Then it's
sufficient to press `Ctrl+R` and enter `<n>`.

#### Working on Laptop
You might want to disable git status autorefresh to save battery.

```
"git.autorefresh": false,
```

#### Editing in multiple Git repositories
If you frequently work in multiple Git repositories that are part of the Chromium repository, you might find that the built-in tooling does not work as expected for files that exist below folders that are part of a `.gitignore` file checked in to Chromium.

To work around this, you can add the directories you edit as separate `folders` entries in your workspace configuration, and ensure that the directories that are ignored in Chromium are listed **before** the Chromium `src` path.

To edit this, go to `Settings` -> Select the `Workspace` tab, and choose to open as JSON (button in the top right), and configure `folders` like this (change paths to match your local setup and usage):

```
{
  "folders": [
    {
      "path": "chromium/src/third_party/perfetto"
    },
    {
      "path": "chromium/src"
    }
  ]
}
```

### Unable to open $File resource is not available when debugging Chromium on Linux
Chromium [recently changed](https://docs.google.com/document/d/1OX4jY_bOCeNK7PNjVRuBQE9s6BQKS8XRNWGK8FEyh-E/edit?usp=sharing)
the file path to be relative to the output dir. Check
`gn args out/$dir --list` if `strip_absolute_paths_from_debug_symbols` is true (which is the default),
set `cwd` to the output dir. otherwise, set `cwd` to `${workspaceRoot}`.

### You-Complete-Me
The You-Complete-Me VS Code extension is now
[deprecated](https://github.com/richard1122/vscode-youcompleteme#deprecated)
with a suggestion to use clangd.

### More
More tips and tricks can be found
[here](https://github.com/Microsoft/vscode-tips-and-tricks/blob/master/README.md).