| .. _ContributingToLibcxx: |
| |
| ====================== |
| Contributing to libc++ |
| ====================== |
| |
| This file contains notes about various tasks and processes specific to contributing |
| to libc++. If this is your first time contributing, please also read `this document |
| <https://www.llvm.org/docs/Contributing.html>`__ on general rules for contributing to LLVM. |
| |
| For libc++, please make sure you follow `these instructions <https://www.llvm.org/docs/Phabricator.html#requesting-a-review-via-the-command-line>`_ |
| for submitting a code review from the command-line using ``arc``, since we have some |
| automation (e.g. CI) that depends on the review being submitted that way. |
| |
| If you plan on contributing to libc++, it can be useful to join the ``#libcxx`` channel |
| on `LLVM's Discord server <https://discord.gg/jzUbyP26tQ>`__. |
| |
| Looking for pre-existing reviews |
| ================================ |
| |
| Before you start working on any feature, please take a look at the open reviews |
| to avoid duplicating someone else's work. You can do that by going to the website |
| where code reviews are held, `Differential <https://reviews.llvm.org/differential>`__, |
| and clicking on ``Libc++ Open Reviews`` in the sidebar to the left. If you see |
| that your feature is already being worked on, please consider chiming in instead |
| of duplicating work! |
| |
| Pre-commit check list |
| ===================== |
| |
| Before committing or creating a review, please go through this check-list to make |
| sure you don't forget anything: |
| |
| - Do you have tests for every public class and/or function you're adding or modifying? |
| - Did you update the synopsis of the relevant headers? |
| - Did you update the relevant files to track implementation status (in ``docs/Status/``)? |
| - Did you mark all functions and type declarations with the :ref:`proper visibility macro <visibility-macros>`? |
| - If you added a header: |
| |
| - Did you add it to ``include/module.modulemap.in``? |
| - Did you add it to ``include/CMakeLists.txt``? |
| - If it's a public header, did you add a test under ``test/libcxx`` that the new header defines ``_LIBCPP_VERSION``? See ``test/libcxx/algorithms/version.pass.cpp`` for an example. NOTE: This should be automated. |
| - If it's a public header, did you update ``utils/generate_header_inclusion_tests.py``? |
| |
| - Did you add the relevant feature test macro(s) for your feature? Did you update the ``generate_feature_test_macro_components.py`` script with it? |
| - Did you run the ``libcxx-generate-files`` target and verify its output? |
| |
| The review process |
| ================== |
| |
| After uploading your patch, you should see that the "libc++" review group is automatically |
| added as a reviewer for your patch. Once the group is marked as having approved your patch, |
| you can commit it. However, if you get an approval very quickly for a significant patch, |
| please try to wait a couple of business days before committing to give the opportunity for |
| other reviewers to chime in. If you need someone else to commit the patch for you, please |
| mention it and provide your ``Name <email@domain>`` for us to attribute the commit properly. |
| |
| Note that the rule for accepting as the "libc++" review group is to wait for two members |
| of the group to have approved the patch, excluding the patch author. This is not a hard |
| rule -- for very simple patches, use your judgement. The `"libc++" review group <https://reviews.llvm.org/project/members/64/>`__ |
| consists of frequent libc++ contributors with a good understanding of the project's |
| guidelines -- if you would like to be added to it, please reach out on Discord. |
| |
| Post-release check list |
| ======================= |
| |
| After branching for an LLVM release: |
| |
| 1. Update ``_LIBCPP_VERSION`` in ``libcxx/include/__config`` |
| 2. Update the version number in ``libcxx/docs/conf.py`` |
| 3. Update ``_LIBCPPABI_VERSION`` in ``libcxxabi/include/cxxabi.h`` |
| 4. Update ``_LIBUNWIND_VERSION`` in ``libunwind/include/__libunwind_config.h`` |
| |
| Exporting new symbols from the library |
| ====================================== |
| |
| When exporting new symbols from libc++, you must update the ABI lists located in ``lib/abi``. |
| To test whether the lists are up-to-date, please run the target ``check-cxx-abilist``. |
| To regenerate the lists, use the target ``generate-cxx-abilist``. |
| The ABI lists must be updated for all supported platforms; currently Linux and |
| Apple. If you don't have access to one of these platforms, you can download an |
| updated list from the failed build at |
| `Buildkite <https://buildkite.com/llvm-project/libcxx-ci>`__. |
| Look for the failed build and select the ``artifacts`` tab. There, download the |
| abilist for the platform, e.g.: |
| |
| * C++20 for the Linux platform. |
| * MacOS C++20 for the Apple platform. |