Visual Studio Code

Install extension

Install the ccls extension from the marketplace here. The source code is located at https://github.com/MaskRay/vscode-ccls.

If you run into issues, you can view debug output by running the (F1) View: Toggle Output command and opening the ccls output section.

To load vscode-ccls without installing:

• code vscode-ccls
• Press F5

Setting up the extension

To tell the extension where to find ccls, either add ccls to your PATH or set "ccls.launch.command" in User Settings to the absolute path pointing to ccls.

"ccls.launch.command": "/path/to/ccls/Release/ccls",

ccls.cacheDirectory

By default, ccls will store indexes in .ccls-cache of the workspace (more technically, the current working directory of ccls, which may not be what you think is the workspace root).

You can set:

"ccls.cacheDirectory": "${workspaceFolder}/.ccls-cache/"

or use a global cache directory:

"ccls.cacheDirectory": "/tmp/ccls-cache/"

ccls.clang.extraArgs

If for whatever reason you cannot generate a compile_commands.json file, you can add the flags to the ccls.clang.extraArgs configuration option.

Semantic highlighting

The Visual Studio Code ccls extension supports semantic highlighting. To enable, put into settings.conf (or workspace configuration):

"ccls.highlighting.enabled.types": true,
"ccls.highlighting.enabled.freeStandingFunctions": true,
"ccls.highlighting.enabled.memberFunctions": true,
"ccls.highlighting.enabled.freeStandingVariables": true,
"ccls.highlighting.enabled.memberVariables": true,
"ccls.highlighting.enabled.namespaces": true,
"ccls.highlighting.enabled.macros": true,
"ccls.highlighting.enabled.enums": true,
"ccls.highlighting.enabled.typeAliases": true,
"ccls.highlighting.enabled.enumConstants": true,
"ccls.highlighting.enabled.staticMemberFunctions": true,
"ccls.highlighting.enabled.parameters": true,
"ccls.highlighting.enabled.templateParameters": true,
"ccls.highlighting.enabled.staticMemberVariables": true,
"ccls.highlighting.enabled.globalVariables": true,

Cross references

You could set custom lookup using keybindings. Use command palette (ctrl + shift + p by default) -> Open keyboard shortcuts file

// functions called by current selected function, up to 3rd level.
{"key":"<ctrl-shift-alt-c>","command":"ccls.call","args":{"callee":true,"levels":3}}

// functions that call this function. This is what "Show Cross References" shows by default
{"key":"<your-shortcuts>","command":"ccls.call"}

// see inheritance instead of base
{"key":"<your-shortcuts>","command":"ccls.base","args":{"derived":true,"levels":2}}

// nested classes / types in a namespace (kind: 2)
{"key":"<your-shortcuts>","command":"ccls.member","args":{"kind":2}}

// member functions / functions in a namespace(kind 3)
{"key":"<your-shortcuts>","command":"ccls.member","args":{"kind":3}}

For VSCodeVim users, here's how to set arguments in User Settings (settings.json)

    "vim.normalModeKeyBindingsNonRecursive": [
        {
            "before":["<leader>","t"],
            "commands":[{"command":"ccls.call","args":{"levels":2,"callee":true}}]
        }
    ]

So you could hit <space>-t to see callees up to 3rd level if you set <leader> to <space>

Using vscode-ccls along side vscode-cpptools extension for debugger support

The vscode-ccls extension doesn't provide any debugger integration. One popular option is to use the vscode-cpptools extension for this aspect. By default however, vscode-cpptools provides editor features that overlap with ccls, which yields duplicate results in things like autocomplete. The following settings may be applied to disable the editor support of vscode-cpptools to prevent this from happening, while still retaining the debugger features.

"C_Cpp.autocomplete": "Disabled",
"C_Cpp.formatting": "Disabled",
"C_Cpp.errorSquiggles": "Disabled",
"C_Cpp.intelliSenseEngine": "Disabled",

Semantic Navigation

The command is ccls.navigate, which need an argument direction. ("D" => first child declaration "L" => previous declaration "R" => next declaration "U" => parent declaration)

    "vim.normalModeKeyBindingsNonRecursive": [
        {"before":["<leader>","j"],"commands":[{"command":"ccls.navigate","args":{"direction":"R"}}]},
        {"before":["<leader>","k"],"commands":[{"command":"ccls.navigate","args":{"direction":"L"}}]},
        {"before":["<leader>","h"],"commands":[{"command":"ccls.navigate","args":{"direction":"U"}}]},
        {"before":["<leader>","l"],"commands":[{"command":"ccls.navigate","args":{"direction":"D"}}]}
    ]