Features — Extra Clang Tools 10 documentation

# Extra Clang Tools 10 documentation

## Features

Contents

- Features
  - Errors and warnings
    - Fixes in errors and warnings
    - clang-tidy checks
  - Code completion
    - Insertion of namespace qualifiers and includes
    - Signature help
  - Cross-references
    - Find definition/declaration
    - Find references
  - Navigation
  - Formatting
  - Complete list of features

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

## Errors and warnings

clangd runs the clang compiler on your code as you type, and shows errors and warnings in-place. Some errors are suppressed: diagnostics that require expanding templates in headers are disabled for performance reasons.

Screenshot

### Fixes in errors and warnings

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

Animated demo

(New in v9) If a missing symbol was seen in a file you’ve edited recently, clangd will suggest inserting it.

### clang-tidy checks

(New in v9) clangd embeds clang-tidy which provides extra hints about code problems: bug-prone patterns, performance traps, and style issues.

Animated demo

clangd respects your project’s `.clang-tidy` file which controls the checks to run. Not all checks work within clangd. You must pass the `-clang-tidy` flag to enable this feature.

## Code completion

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

Screenshot

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.

### Insertion of namespace qualifiers and includes

(New in v8) clangd will sometimes suggest results from other files and namespaces. In this case the correct qualifier and `#include` directive will be inserted.

Animated demo

### Signature help

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

Animated demo

## Cross-references

The following features let you navigate your codebase.

If there is no project-wide index, cross-references work across the files you have opened.

(New in v9) clangd will also automatically index your whole project.

### Find definition/declaration

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

Animated demo

(New in v9) Some editors only expose “find definition”; use “find definition” on the definition to jump to the declaration.

“Find definition” also works on `#include` lines, to jump to the included file.

### Find references

Show all references to a symbol under the cursor.

Animated demo

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

## Navigation

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

Screenshot

In VSCode, the outline is also presented as breadcrumbs that allow jumping to a symbol within the current file. Searching for symbols within the scope of the whole project is also possible.

Animated demo

## Formatting

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

Animated demo

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

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

## Complete list of features

Here is a list of features that could be useful for editors, together with the implementation status in clangd, and specification in the Language Server Protocol.

It is not clear whether or not some of the features mentioned below should be a part of the Language Server Protocol; those features might be eventually developed outside clangd or become clangd extensions to LSP.

C/C++ Editor feature | LSP | Clangd
--- | --- | ---
Formatting | Yes | Yes
Completion | Yes | Yes
Diagnostics | Yes | Yes
Fix-its | Yes | Yes
Go to Definition | Yes | Yes
Signature Help | Yes | Yes
Document Highlights | Yes | Yes
Rename | Yes | Yes
Source hover | Yes | Yes
Find References | Yes | Yes
Document Symbols | Yes | Yes
Workspace Symbols | Yes | Yes
Code Lens | Yes | No
Code folding | Yes | No
Extract Local Variable | Yes | No
Extract Function/Method | Yes | No
Quick Assist | Yes | No
Hide Method | Yes | No
Implement Method | Yes | No
Gen. Getters/Setters | Yes | No
Syntax and Semantic Coloring | Proposed [1] | Yes
Call hierarchy | Proposed [2] | No
Type hierarchy | Proposed [3] | Yes
Organize Includes | Yes | No

[1] | https://github.com/microsoft/language-server-protocol/issues/18

[2] | https://github.com/microsoft/language-server-protocol/issues/468

[3] | https://github.com/microsoft/language-server-protocol/issues/136