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Extensions for C++ on Linux

Out of the box, most editors treat C++ as plain text. The extensions below add code navigation, autocompletion, error checking, formatting, and debugging. The examples assume VS Code (or a fork such as Cursor), but the underlying tools (clangd, gdb, cmake) are editor-agnostic.

clangd (language server) — the important one​

clangd is an LLVM language server that provides the features that actually make C++ pleasant:

  • Accurate autocompletion and go-to-definition/find-references.
  • Real-time diagnostics (errors and warnings as you type).
  • Inlay hints, call hierarchy, and rename refactoring.
  • Integrated clang-tidy and clang-format.

VS Code extension: llvm-vs-code-extensions.vscode-clangd. Zed has clangd support built in.

note

There are two competing C++ setups for VS Code: Microsoft's C/C++ (ms-vscode.cpptools) extension and clangd. We recommend clangd — it is open source, generally more accurate, and works in open-source builds like VSCodium. Do not enable both at once; their IntelliSense engines conflict. If you use clangd, disable IntelliSense in the Microsoft extension (or don't install it).

Install clangd itself​

The extension needs the clangd binary. On the machine where your code lives (the remote host, for HPC work):

# Debian/Ubuntu
sudo apt-get install -y clangd

# or via spack (see the Installing HPC Software section)
spack install llvm

Give clangd a compile database​

clangd needs to know how each file is compiled (include paths, defines, standard version). This is provided by a compile_commands.json file. With CMake, generate it automatically:

cmake -S . -B build -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
# then point clangd at it, e.g. symlink into the project root:
ln -s build/compile_commands.json .

Without this, clangd will guess and you'll see spurious "file not found" errors on your #includes.

CMake Tools​

ms-vscode.cmake-tools adds a UI for configuring, building, and debugging CMake projects — pick a kit (compiler), configure, and build from the status bar instead of retyping cmake commands. Pairs well with clangd (let CMake Tools drive the build, let clangd handle IntelliSense). See the Build with CMake tutorial.

Debugging​

For step debugging, install a debugger and a debug-adapter extension:

  • Install gdb (or lldb) on the target machine: sudo apt-get install -y gdb.
  • VS Code's built-in C++ debugging uses the ms-vscode.cpptools extension's debug adapter (you can install it for debugging only and still use clangd for IntelliSense), or the CodeLLDB extension for an LLDB-based debugger.
  • Remember to compile with debug symbols: -g (or -DCMAKE_BUILD_TYPE=Debug).

Remote development (HPC)​

For working on a cluster, install ms-vscode-remote.remote-ssh. It runs clangd and your build on the remote host, so IntelliSense reflects the cluster's exact headers and compilers. Install clangd/CMake Tools in the remote context once connected.

Formatting and linting​

Both ship with LLVM and are picked up automatically by clangd:

  • clang-format — enforce a consistent style. Drop a .clang-format file in your repo (for our code we use the Google C++ style: clang-format -style=google -dump-config > .clang-format).
  • clang-tidy — static analysis for bug-prone patterns; configure with a .clang-tidy file.
  1. clangd — IntelliSense and navigation.
  2. CMake Tools — configure/build/debug CMake projects.
  3. Remote - SSH — if you develop on a cluster.
  4. A debugger extension (CodeLLDB or cpptools) + gdb/lldb.