Clang-format version mismatch: Ubuntu 24 uses 18.x, cpptools bundles 21.x → inconsistent formatting & config parse errors

[SanjanaNingappa]

Environment

• Host OS: Linux
• Dev environment: Ubuntu 24.04 (local / Docker )
• VS Code: 1.108.1
• C/C++ Extension: ms-vscode.cpptools 1.29.3
• System clang-format: 18.1.3 (Ubuntu default)
• Bundled clang-format: 21.1.4 (extension's LLVM/bin)

Bug Summary and Steps to Reproduce

Bug Summary:

The ms-vscode.cpptools extension’s bundled clang-format (21.1.4) supports newer .clang-format keys than the system clang-format on Ubuntu 24 (18.1.3).
If "C_Cpp.clang_format_path" is set to /usr/bin/clang-format, formatting can fail due to unsupported keys or give different results.

Steps to reproduce:

1. On Ubuntu 24:

sudo apt install clang-format
  clang-format --version  # 18.1.3

2..clang-format:

 BasedOnStyle: LLVM
 SpaceAroundPointerQualifiers: After

3. Open a C++ file and format in VS Code:

Without C_Cpp.clang_format_path → works (bundled 21.1.4).
With C_Cpp.clang_format_path": "/usr/bin/clang-format" → fails with:

#define test ((status_t (*)) addr_test)

See error
error: invalid configuration key 'SpaceAroundPointerQualifiers'

Expected behavior:
Ability to use the bundled clang-format (21.x) in Linux/Docker without having to upgrade the system version.

Actual Behavior

• Bundled (21) and system (18) behave differently.
• Keys supported by 21 break with 18.
• Upgrading requires adding LLVM apt repo manually.

Configuration and Logs

{// Use workspace .clang-format style file for formatting
    "C_Cpp.clang_format_style": "file:${workspaceFolder}/.clang-format",
    "C_Cpp.formatting": "clangFormat",
    "C_Cpp.clang_format_fallbackStyle": "none",
    "C_Cpp.intelliSenseEngine": "default",
    "C_Cpp.enhancedColorization": "enabled",
    "C_Cpp.errorSquiggles": "enabled",
    "C_Cpp.autocompleteAddParentheses": true,
    "C_Cpp.workspaceParsingPriority": "medium",

    // Auto-format when saving
    "editor.formatOnSave": true,
    "editor.formatOnSaveMode": "file",

    // Default formatter for C/C++
    "[c]": {
        "editor.defaultFormatter": "ms-vscode.cpptools"
    },
    "[cpp]": {
        "editor.defaultFormatter": "ms-vscode.cpptools"
    },

Other Extensions

No response

Additional context

No response

[sean-mcmanus]

What is the problem with using the bundled 21.4 with C_Cpp.clang_format_path not set? It sounds like you're saying it's working. If you set C_Cpp.clang_format_path to and older version, the older version won't work with newer configurations.