Understanding the Usage of 'clangd' (with examples)

Clangd is a language server that brings many of the features you would expect in an Integrated Development Environment (IDE) to your favorite text editors and development environments. It’s a crucial tool for developers working with C, C++, and other languages that clang supports, providing features like code completion, navigation, real-time diagnostics, and more. Although clangd operates primarily through editor plugins, it is accessible from the command line with various options for configuration and information.

Use case 1: Display available options

Code:

clangd --help

Motivation:

Using the --help option is a fundamental first step for any developer who is looking to explore the capabilities of a tool like clangd. This command provides a detailed overview of all the available options and commands that clangd can execute. It serves as a crucial reference point for both new users and experienced developers to verify command usage, discover new features, and troubleshoot potential issues in their workflow.

Explanation:

• clangd: This is the command that invokes the clang language server.
• --help: This argument instructs clangd to display a help message that includes a list of common options and usage instructions. It’s a standard argument in command-line tools to inform the user about how to use the command and what options are available.

Example output:

OVERVIEW: Clang Language Server

USAGE: clangd [options] 

OPTIONS:
  --compile-commands-dir=<string>    Specify the directory to look for compile_commands.json
  --background-index=<bool>          Index project code in the background and persist index on disk
  --log=<Level>                      Adjust the verbosity of logs (verbose, info, error)

  (Other options follow...)

Use case 2: List of available options

Code:

clangd --help-list

Motivation:

The --help-list command is especially useful when you need a comprehensive view of all possible command-line options available in clangd. This list allows you to quickly see every option without the explanatory text that usually accompanies a standard --help output. It’s particularly handy for advanced users who are familiar with the terms and concepts and are looking for a quick index of available functionalities.

Explanation:

• clangd: This is again the main command that initiates the clang language server.
• --help-list: This argument outputs a list of available options without detailed descriptions. It is useful for scripting or for users who want to see all options in a concise format.

Example output:

--compile-commands-dir
--background-index
--enable-config
--index
--log
--pretty
--query-driver

Use case 3: Display version

Code:

clangd --version

Motivation:

Knowing the version of clangd you are working with is essential for compatibility and debugging. The --version command provides this information, which is particularly important when integrating with plugins or scripts that may rely on specific features introduced in certain versions. Developers can ensure they have the necessary features and bug fixes, and also report precise version information when seeking help or submitting bug reports.

Explanation:

• clangd: The core command to run the clang language server.
• --version: This argument prompts clangd to output the current version information. It typically includes detailed build information that can help deduce the environment and compiler features.

Example output:

clangd version 12.0.0 (git hash)

Conclusion:

Using clangd from the command line, although less common due to its primary use via IDE plugins, can provide valuable insights into the tool’s capabilities. Commands such as --help, --help-list, and --version offer essential information that aids in maximizing efficiency, ensuring compatibility, and empowering developers to utilize clangd optimally. Whether you’re setting up a new development environment or troubleshooting an existing one, these commands form the backbone of initial clangd configuration and understanding.