What's Changed

Toolchain and implementation changes :hammer_and_wrench:

• Add bitwise homogeneous operators for CppCompat.Long32 by @ivanaivanovska in https://github.com/carbon-language/carbon-lang/pull/6584
• Add a dependency for the StringRef.h header by @chandlerc in https://github.com/carbon-language/carbon-lang/pull/6605
• Fix crash if a member of std::string_view is found in a derived class. by @zygoloid in https://github.com/carbon-language/carbon-lang/pull/6604
• Store and reuse lowered parameter order by @geoffromer in https://github.com/carbon-language/carbon-lang/pull/6593

Documentation changes :memo:

• Update to AI-based tooling policy by @chandlerc in https://github.com/carbon-language/carbon-lang/pull/6477

Infrastructure changes :building_construction:

• Refactor handling of -std and -stdlib in toolchain by @chandlerc in https://github.com/carbon-language/carbon-lang/pull/6601
• Extract C++-specific features into their own file by @chandlerc in https://github.com/carbon-language/carbon-lang/pull/6606
• Move the libc++ hardening to be part of libcxx_feature by @chandlerc in https://github.com/carbon-language/carbon-lang/pull/6607
• Fix OS config features and use them to move OS-specific flags by @chandlerc in https://github.com/carbon-language/carbon-lang/pull/6608

Full Changelog: https://github.com/carbon-language/carbon-lang/compare/v0.0.0-0.nightly.2026.01.15...v0.0.0-0.nightly.2026.01.16