clangd LSP

C/C++ language server integration providing comprehensive code intelligence through clangd (part of LLVM).

Capabilities

• Code intelligence: Autocomplete, go-to-definition, find references
• Error detection: Real-time diagnostics for compilation errors
• Formatting: Code formatting with clang-format
• Refactoring: Rename symbols, extract function
• Supported extensions: .c, .h, .cpp, .cc, .cxx, .hpp, .hxx, .C, .H

Installation

Via Homebrew (macOS)

brew install llvm
# Add to PATH
export PATH="/opt/homebrew/opt/llvm/bin:$PATH"

Via package manager (Linux)

# Ubuntu/Debian
sudo apt install clangd

# Fedora
sudo dnf install clang-tools-extra

# Arch Linux
sudo pacman -S clang

Windows

winget install LLVM.LLVM

Or download from LLVM releases.

Verify installation:

clangd --version

Usage

The language server runs automatically in LSP-compatible editors. For manual operations:

Compile

gcc file.c -o output      # C
g++ file.cpp -o output    # C++
clang file.c -o output    # with clang

Format code

clang-format -i file.cpp

Static analysis

clang-tidy file.cpp -- -std=c++17

Configuration

Create .clangd in project root:

CompileFlags:
  Add: [-std=c++17, -Wall, -Wextra]
  Remove: [-W*]
Diagnostics:
  UnusedIncludes: Strict
  MissingIncludes: Strict

Or compile_commands.json for complex projects:

cmake -DCMAKE_EXPORT_COMPILE_COMMANDS=ON .
# or
bear -- make

Integration Pattern

When editing C/C++ code:

1. clangd uses compile_commands.json for project understanding
2. Run clang-format to format code
3. Use clang-tidy for static analysis
4. Compile with warnings enabled (-Wall -Wextra)

Common Flags

Compile flags:

• -std=c++17 - C++17 standard
• -Wall -Wextra - Enable warnings
• -O2 - Optimization level
• -g - Debug symbols
• -I<path> - Include path
• -L<path> - Library path

clang-tidy checks:

clang-tidy file.cpp --checks='*' --
clang-tidy file.cpp --fix --  # Auto-fix

More Information

• clangd Website
• Getting Started Guide
• LLVM Project