Re: [boost] Interest for C++20 modules support of boost officially

Chuanqi Xu wrote:

For authors of libraries, after boost introduce modules, you only need to do 2 extra things: - In headers, add a macro (assume its name as BOOST_MODULE_EXPORT, which will be ‘export’ conditionally) to the entities that need to be exported. - In headers, include standard headers and other dependent headers conditionally so that we don’t include anything if the headers are in a module unit. e.g., https://github.com/boostorg/pfr/blob/f09e6aeae9d050897fff72b93d5f5e866cc5e11...

For a header-only library with no dependencies, you can basically do whatever you like, but in the general case you'd have something like #ifdef BOOST_USE_MODULE_CORE import boost.core; #else #include #include #endif repeated for every library you #include things from. And the end user will have to do this too. I'm also not quite clear on how things will work on the CMake side. I can envisage the add_subdirectory case working, more or less, but what would (or needs to) happen when Boost is _installed_ via CMake, with module support enabled? And how will it then be consumed on the user side, after find_package? Also, we're basically talking Clang-only here, right? GCC doesn't work and MSVC... may or may not work?