Features

Here is what clangd can do for you. Screenshots show VSCode; the available features and UI will depend on your editor.

Contents

Errors and warnings

clangd runs the clang compiler on your code as you type, and shows diagnostics of errors and warnings in-place.

screenshot: clang errors

(Some errors are suppressed: diagnostics that require expanding templates in headers are disabled for performance reasons).

Fixes

The compiler can suggest fixes for many common problems automatically, and clangd can update the code for you.

screenshot: apply fix

If a missing symbol was seen in a file you’ve edited recently, clangd will suggest inserting it.

screenshot: include-fixer fix

clang-tidy checks

clangd embeds clang-tidy which provides extra hints about code problems: bug-prone patterns, performance traps, and style issues.

screenshot: apply clang-tidy fix

clangd respects your project’s .clang-tidy file which controls the checks to run. Not all checks work within clangd.

Code completion

You’ll see suggestions as you type based on what methods, variables, etc are available in this context.

screenshot: code completion

Abbreviating words may help you find the right result faster. If you type in camelCase but the function you’re looking for is snake_case, that’s OK.

Namespace and include insertion

clangd will sometimes suggest results from other files and namespaces. In this case the correct qualifier and #include directive will be inserted.

screenshot: code completion insert ns

Signature help

Some editors will show you the parameters of the function you’re calling, as you fill them in.

screenshot: signature help

Cross-references

These features let you navigate your codebase.

They work across the files you’ve opened.

clangd will also automatically index your whole project.

Find definition/declaration

Jump to the definition or declaration of a symbol under the cursor.

screenshot: go to def

(Some editors only expose “find definition” - hit it again to jump to the declaration).

This also works on #include lines, to jump to the included file.

Find references

Show all references to a symbol under the cursor.

screenshot: find references

Some editors will automatically highlight local references to the selected symbol as you move around a file.

clangd informs the editor of the code structure in the current file. Some editors use this to present an outline view:

screenshot: outline

In VSCode, this also allows jumping to a symbol within the current file.

Searching for symbols within the scope of the whole project is also possible.

screenshot: navigation

Hover

Hover over a symbol to see more information about it, such as its type, documentation, and definition.

screenshot: hover

Hovering over auto will show the underlying type.

Formatting

clangd embeds clang-format, which can reformat your code: fixing indentation, breaking lines, and reflowing comments.

screenshot: format selection

clangd respects your project’s .clang-format file which controls styling options.

(Format-as-you-type is experimental and doesn’t work well yet).

Refactoring

Rename

Rename a symbol under the cursor. All usages of the symbol will be renamed, including declaration, definition and references.

screenshot: rename

Most symbols are renameable, such as classes, variables, functions and methods.

Known limitations

TIP: the rename workflow highly depends on the editor you are using. Some editors, e.g. VSCode, provide a way to preview the rename changes before applying them; while some just apply the changes directly.

Within-file rename

The default mode only allows to rename a local symbol (one which is only used in current file).

Cross-file rename

This mode allows renaming symbols used in several files. It is enabled with the command-line flag -cross-file-rename.

It uses the project index to find all renamed references quickly, so works best when the index is up-to-date.