setup-cpp-language-server

Using the LSP tool with C++ requires three configuration files before it will work correctly:

1. A .github/lsp.json file that specifies how to launch the language server. It should have content like this:

{
  "lspServers": {
    "cpp": {
      "command": "mscppls",
      "args": ["--lsp-config", ".mscppls/cpp-lsp.json"],
      "fileExtensions": {
        ".cpp": "cpp",
        ".cxx": "cpp",
        ".c": "cpp",
        ".cc": "cpp",
        ".hpp": "cpp",
        ".hxx": "cpp",
        ".hh": "cpp",
        ".h": "cpp"
      },
      "requestTimeoutMs": 1000000
    }
  }
}

2. A .mscppls/cpp-lsp.json file that configures the path to the compile_commands.json file. This file must follow the schema below, where all paths are relative to the .mscppls directory. repositoryPath is the relative path to the repository root and compileCommands is the relative path to the compile_commands.json file.

{
 "repositoryPath": "../",
 "compileCommands": "../build/compile_commands.json"
}

3. A compile_commands.json file that specifies the compile command lines for each file in the project. This file can exist anywhere in the project and is typically produced by the build system.

Your job is to ensure these configuration files are correctly set up.

1. If all required files exist and appear correct, stop. All checks have passed and it's okay to run the C++ LSP tools. Note that your built-in search tools often ignore files in the build directory, so double-check using terminal commands.
2. If compile_commands.json does not exist, help the user create the file for their project. Don't complete any other tasks and ensure the compile_commands.json file is created before continuing. a. For CMake projects, it's often possible to produce the file by including -DCMAKE_EXPORT_COMPILE_COMMANDS=ON. This option is not supported when using the Visual Studio generators (default for CMake on Windows), but it is supported with Ninja and Makefile generators. b. For MSBuild-based C++ projects (.vcxproj, .sln, .slnx), use msbuild-extractor-sample to generate the file. Prefer committing a msbuild-extractor.json config file at the workspace root so the tool runs with no arguments (msbuild-extractor-sample.exe, which auto-detects ./msbuild-extractor.json); otherwise pass flags directly, e.g. msbuild-extractor-sample.exe --solution path\to\app.sln -c Debug -a x64 -o compile_commands.json.
3. If .mscppls/cpp-lsp.json does not exist, create it based on the path to the compile_commands.json file.
4. If .github/lsp.json does not exist or does not have an entry for C++, create or update it to include the configuration shown above. Make sure the args field points to the correct path to cpp-lsp.json.
5. If you made any changes to compile_commands.json, .mscppls/cpp-lsp.json, or .github/lsp.json, guide the user to restart their chat session before using the C++ LSP tools. The tools need to be restarted.