New standard procedure

Roughly every three years, WG21 finishes a version of the C++ standard and starts working on the next one. This page describes the procedure that libc++ developers must follow to introduce support for a new version of the standard in the library. Since introducing a new Standard does not happen often, this document may not be fully exhaustive and is meant as a starting point. Keep it up-to-date when drift is noticed.

• Create status pages for tracking conformance of C++ZZ (CxxZZIssues.csv, CxxZZPapers.csv and related).

• Create the associated views in the libc++ Conformance project.

• CI updates

  • Add a new job testing C++ZZ

  • Move jobs that specify the previous standard over to C++ZZ (except jobs which intend to test older standard specifically)

• Teach the test suite about C++ZZ (for example --param std=c++zz in the Lit configuration)

• Add files to track the transitive includes for C++ZZ

• Add a new version for _LIBCPP_STD_VER and TEST_STD_VER for the test suite

  • Note that we don’t add various versioned macros until we need them (e.g. _LIBCPP_CONSTEXPR_SINCE_CXXZZ)

• Feature-test macros:

  • Update the FTM generation script to account for C++ZZ

  • Add any missing FTMs for the new standard version in the FTM generation script

  • Regenerate the FTM files

  • Update the tests for the FTM generation script itself