On Mon, 25 Jul 2022 at 10:49, Zopolis0 via Gcc <gcc@gcc.gnu.org> wrote: > > Currently, when importing the standard library, one has to > separately compile each unit they want to use, which is a hindrance to the > build process and a gap in the implementation. > > Is there any particular reason why gcc doesn't provide importable header > units for the standard library? Is there a timeline for this? Given that > the standard library can already be compiled into header units, is there > any particular reason why those aren't shipped with gcc?
Are you asking why GCC doesn't install compiled module interface files for the std::lib headers? Those would have to be built with a specific set of compiler options, and then would only work if you compile with those same options. Should they enable C++20 features, or C++23 as well? Should they be built with assertions enabled? etc. etc. Those seem like things that should be decided by the user consuming those header units, not by the GCC project. More generally, GCC's support for modules (and all of C++20) is still experimental, so I don't think we're ready to be installing CMI files yet. If you disagree, feel free to propose patches to install header units. Changes like that happen because somebody works on it, not by magic. Later today the C++ committee is likely to approve https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2465r3.pdf for C++23, and I think implementing that would be a far better use of our limited resources than providing importable header units.
