This is a wrapper around Herb Sutter's cppfront compiler. Go there to learn more about that project.

This repository adds a CMake build with some "magic" helpers to make it easier to use cpp2. Requires CMake 3.30+.

Disclaimer: As cppfront is highly experimental, expect abrupt, backwards-incompatible changes to be made here, too. This isn't a production-ready ecosystem, and breaking changes will be made if they improve the overall project. We're on [major-version 0] for the foreseeable future.

Note: This work might one day be merged upstream. The open pull request is here: hsutter/cppfront#15

PRs are welcome, but please know CMake well.

See the example for a full example project.

This is the workflow I will personally support.

Build this repository:

$ git clone --recursive https://github.com/modern-cmake/cppfront
$ cmake -S cppfront -B build -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/wherever
$ cmake --build build --target install

Now just write your project like normal:

cmake_minimum_required(VERSION 3.30)
project(example)

find_package(cppfront REQUIRED)

add_executable(main main.cpp2)

And that's literally it. Any targets with a .cpp2 source will automatically get custom commands added to them. They will also be scanned for modules by CMake; this requires you to use a compiler that supports this. See the cxx-modules documentation for more detail. As of CMake 3.29, this includes:

• MSVC toolset 14.34 and newer (provided with Visual Studio 17.4 and newer)
• LLVM/Clang 16.0 and newer
• GCC 14 (for the in-development branch, after 2023-09-20) and newer

FetchContent is also supported, though as always with FetchContent, there's a chance it will be wonky.

Here's the code.

cmake_minimum_required(VERSION 3.30)
project(example)

include(FetchContent)

FetchContent_Declare(
    cppfront
    GIT_REPOSITORY https://github.com/modern-cmake/cppfront.git
    GIT_TAG main  # or an actual git SHA if you don't like to live dangerously
)

FetchContent_MakeAvailable(cppfront)

add_executable(main main.cpp2)

The same automatic configuration will happen here, too. Though since FetchContent_MakeAvailable will only run our CMakeLists.txt once, the magic can only happen in the first directory to include it. Thus, you should probably explicitly run cppfront_enable(TARGETS main) and add set(CPPFRONT_NO_MAGIC 1) if you want your project to be consumable via FetchContent. Blech.

You can, of course, use this repo as a submodule and call add_subdirectory rather than using FetchContent. It's basically the same except FetchContent can be overridden using FIND_PACKAGE_ARGS.

I won't personally address issues for FetchContent users.

No matter how you use this CMake build, it exposes the following points of configuration:

• cppfront::cppfront -- this is the executable for the cppfront compiler
• cppfront::cpp2util -- this is an INTERFACE library providing the path to the cpp2util.h and cpp2regex.h runtime headers.

Universal:

• CPPFRONT_NO_MAGIC -- off by default. When enabled, skips the automatic cpp2-to-cpp translation.
• CPPFRONT_FLAGS -- a semicolon-separated list of additional flags to pass to cppfront. For now, these are assumed to be universal to a project, and it is not supported to change them after the package has loaded, whether via find_package, add_subdirectory, FetchContent, or any other mechanism.

FetchContent-only:

• CPPFRONT_NO_SYSTEM -- off by default. When enabled, skips marking the cpp2util.h header as SYSTEM, meaning that warnings generated by that header will be shown.
• CPPFRONT_INSTALL_RULES -- off by default. When enabled, runs the install() and packaging rules. Everything is placed in a component named cppfront.

• CPPFRONT_EXECUTABLE -- find_package-only. This is the absolute path to the cppfront executable file. This is sometimes useful in limited scenarios where neither the cppfront::cppfront target, nor the $<TARGET_FILE:cppfront::cppfront> generator expression can be used.

cppfront_generate_cpp(<OUTVAR> <cpp2 files>...)

Writes to the variable named by OUTVAR a list of absolute paths to the generated .cpp files associated with each .cpp2 file in the arguments list. A hashing scheme prevents cppfront from running on the same .cpp2 file multiple times.

cppfront_enable(
    TARGETS <targets>...
)

Scans the SOURCES properties for each target in <targets> for entries ending in .cpp2. These are passed to cppfront_generate_cpp and the results are added to the target automatically. When CPPFRONT_NO_MAGIC is unset (i.e. by default), this command runs on all targets in the directory that imported this package at the end of processing the directory.

The CMake project regression-tests/CMakeLists.txt runs the test suite of cppfront. Read test-all.sh to see how to set it up. To have the test results updated, configure with -DCPPFRONT_DEVELOPING=TRUE.