cpp26-init

/cpp26-init — scaffold a C++26 project

Run this once per project to wire up the toolchain expectations the cpp26-adapter plugin assumes. The command is idempotent: re-running on a configured project diffs against the desired state and only writes files that are missing or out-of-date. Existing user content is never clobbered without a backup.

What this does

1. Detect the project root. Walk up from the current directory looking for .git, CMakeLists.txt, or package.json. If none exists, use the current directory.

2. CMakeLists.txt — if missing, scaffold a minimal C++26 project:

   cmake_minimum_required(VERSION 3.28)
   project(my_project LANGUAGES CXX)
   
   set(CMAKE_CXX_STANDARD 26)
   set(CMAKE_CXX_STANDARD_REQUIRED ON)
   set(CMAKE_CXX_EXTENSIONS OFF)
   set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
   
   # Pin -std=c++2c so build is portable even when compilers don't
   # recognize CXX_STANDARD 26 yet.
   add_compile_options(-std=c++2c)
   
   add_executable(my_project main.cpp)
   

   If CMakeLists.txt already exists:

   • Check for set(CMAKE_CXX_STANDARD 26) (or equivalent). If missing or set lower, emit a suggested patch but do not apply it without consent.
   • Check for CMAKE_EXPORT_COMPILE_COMMANDS. If missing, suggest adding it (clangd-driven editing depends on this).

3. .clangd — if missing, scaffold:

   CompileFlags:
     Add:
       - "-std=c++2c"
       - "-Wno-unknown-pragmas"  # quiet pragmas the user has opted into
     # If the user has clang-p2996 installed elsewhere:
     # CompilerPath: /opt/clang-p2996/bin/clang++
   
   Diagnostics:
     UnusedIncludes: Strict
     MissingIncludes: Strict
     ClangTidy:
       Add: [modernize-*, performance-*]
       Remove: [modernize-use-trailing-return-type]
   

4. .cpp26-adapter.yaml — write a default that opts the project into the plugin's defaults:

   # cpp26-adapter project overrides.
   #   Set skip-skill: true to disable the cpp26-idioms skill for
   #   legacy modules that should remain pre-C++26 idiomatic.
   #   Add anti-pattern ids to allow-list to silence specific
   #   PostToolUse findings.
   skip-skill: false
   allow-list: []
   # Optional: override the compiler the reviewer uses on this project.
   # compiler: clang-p2996