[libc++][hardening][NFC] Fix the 17 release notes to remove mentions of hardening

[var-const]

Summary

This is to bring main in sync with release/17.x after https://reviews.llvm.org/D159171.

[ldionne]

libcxx/docs/ReleaseNotes/17.rst

82

We also discussed updating some TODO(LLVM18) blocks, I think those are missing from the patch.

131

Don't we need to advertise this in LLVM 18 now?

[var-const]

Address feedback

libcxx/docs/ReleaseNotes/17.rst

82

Hmm, do you have something specific in mind? I couldn't find any of those TODOs in the release notes or documentation. There are a couple in __config and CMakeLists.txt, but I thought to keep this patch limited to just the docs (but of course it doesn't have to be if you'd prefer to do everything in one go).

[ldionne]

libcxx/docs/ReleaseNotes/17.rst

82

I think it makes sense for this patch to fix all the discrepancies introduced by the last-minute change we made on release/17.x (in one go). I could find this with grep: # TODO(LLVM 18): Remove this after branching for LLVM 17, this is a simple [...]. There's probably others!

[var-const]

Address feedback

libcxx/docs/ReleaseNotes/17.rst

82

I found 3 such TODOs and bumped the LLVM release version. Please let me know if that's not what you had in mind!

libcxx/CMakeLists.txt

if (LIBCXX_HARDENING_MODE STREQUAL "hardened")
   config_define(0 _LIBCPP_ENABLE_DEBUG_MODE_DEFAULT)
 elseif (LIBCXX_HARDENING_MODE STREQUAL "debug")
   config_define(0 _LIBCPP_ENABLE_HARDENED_MODE_DEFAULT)
   config_define(1 _LIBCPP_ENABLE_DEBUG_MODE_DEFAULT)
 elseif (LIBCXX_HARDENING_MODE STREQUAL "unchecked")
   config_define(0 _LIBCPP_ENABLE_HARDENED_MODE_DEFAULT)
   config_define(0 _LIBCPP_ENABLE_DEBUG_MODE_DEFAULT)
 endif()
-# TODO(LLVM 18): Remove this after branching for LLVM 17, this is a simple
+# TODO(LLVM 19): Remove this after branching for LLVM 18, this is a simple
 # courtesy for vendors to be notified about this change.
 if (LIBCXX_ENABLE_ASSERTIONS)
   message(FATAL_ERROR "LIBCXX_ENABLE_ASSERTIONS has been replaced by LIBCXX_HARDENING_MODE=hardened")
 endif()
 
 if (LIBCXX_PSTL_CPU_BACKEND STREQUAL "serial")
   config_define(1 _LIBCPP_PSTL_CPU_BACKEND_SERIAL)
 elseif(LIBCXX_PSTL_CPU_BACKEND STREQUAL "std_thread")

libcxx/docs/ReleaseNotes/17.rst

 
 - P0645 - Text Formatting
 - P1652 - Printf corner cases in std::format
 - P1892 - Extended locale-specific presentation specifiers for std::format
 - P1868 - width: clarifying units of width and precision in std::format
 - P2216 - std::format improvements
 - P2418 - Add support for std::generator-like types to std::format
 - P2286R8 - Formatting Ranges
 - P2508R1 - Exposing std::basic-format-string
 
 Improvements and New Features
 -----------------------------
 - ``std::equal``, ``std::ranges::equal``, ``std::find``, and
   ``std::ranges::find``  are now forwarding to ``std::memcmp`` for trivially
   equality comparable types, which can lead up to 40x performance improvements.
 
-- ``std::string_view`` now provides iterators that check for out-of-bounds accesses when the safe
-  libc++ mode is enabled.
-
 - The performance of ``dynamic_cast`` on its hot paths is greatly improved and is as efficient as the
   ``libsupc++`` implementation. Note that the performance improvements are shipped in ``libcxxabi``.
 
 - `D122780 <https://reviews.llvm.org/D122780>`_ Improved the performance of ``std::sort`` and ``std::ranges::sort``
   by up to 50% for arithmetic types and by approximately 10% for other types.
 
 - The ``<format>`` header is no longer considered experimental. Some
   ``std::formatter`` specializations are not yet available since the class used

 - ASan annotations have been added to the ``std::deque`` container, to detect container overflows.
 
 - On Windows, ``std::wcout``, ``wcin``, and ``wcerr`` now work correctly when the underlying
   stream has been configured in wide mode.
 
 Deprecations and Removals
 -------------------------
 
-- The "safe" mode is replaced by the hardened mode in this release. The ``LIBCXX_ENABLE_ASSERTIONS`` CMake variable is
-  deprecated and setting it will trigger an error; use ``LIBCXX_HARDENING_MODE`` instead. Similarly, the
-  ``_LIBCPP_ENABLE_ASSERTIONS`` macro is deprecated and setting it to ``1`` now enables the hardened mode. See
-  ``libcxx/docs/Hardening.rst`` for more details.
-
-- The legacy debug mode has been removed in this release. Setting the macro ``_LIBCPP_ENABLE_DEBUG_MODE`` to ``1`` now
-  enables the new debug mode which is part of hardening (see the "Improvements and New Features" section above). The
-  ``LIBCXX_ENABLE_DEBUG_MODE`` CMake variable has been removed. For additional context, refer to the `Discourse post
+- The legacy debug mode has been removed in this release. The ``LIBCXX_ENABLE_DEBUG_MODE`` CMake variable has been
+  removed. For additional context, refer to the `Discourse post
   <https://discourse.llvm.org/t/rfc-removing-the-legacy-debug-mode-from-libc/71026>`_.
 
 - The ``<experimental/coroutine>`` header has been removed in this release. The ``<coroutine>`` header
   has been shipping since LLVM 14, so the Coroutines TS implementation is being removed per our policy
   for removing TSes.
 
 - Several incidental transitive includes have been removed from libc++. Those
   includes are removed based on the language version used. Incidental transitive

libcxx/docs/ReleaseNotes/18.rst

 Note that if you are reading this file from a Git checkout or the
 main Libc++ web page, this document applies to the *next* release, not
 the current one. To see the release notes for a specific release, please
 see the `releases page <https://llvm.org/releases/>`_.
 
 What's New in Libc++ 18.0.0?
 ==============================
 
+- The "safe" mode is replaced by the hardened mode in this release. The
+  ``LIBCXX_ENABLE_ASSERTIONS`` CMake variable is deprecated and setting it will
+  trigger an error; use ``LIBCXX_HARDENING_MODE`` instead. Similarly, the
+  ``_LIBCPP_ENABLE_ASSERTIONS`` macro is deprecated and setting it to ``1`` now
+  enables the hardened mode. See ``libcxx/docs/Hardening.rst`` for more details.
+
+- A new debug mode has been added, replacing the legacy debug mode that was
+  removed in the LLVM 17 release. See ``libcxx/docs/Hardening.rst`` for more
+  details.
 
 Implemented Papers
 ------------------
 
 - P2497R0 - Testing for success or failure of ``<charconv>`` functions
 - P2697R1 - Interfacing ``bitset`` with ``string_view``
 - P2443R1 - ``views::chunk_by``
 

libcxx/include/__config

 // - `string_view`;
 // - `array`.
 // #define _LIBCPP_ABI_BOUNDED_ITERATORS
 
 // } ABI
 
 // HARDENING {
 
-// TODO(hardening): remove this in LLVM 18.
+// TODO(hardening): remove this in LLVM 19.
 // This is for backward compatibility -- make enabling `_LIBCPP_ENABLE_ASSERTIONS` (which predates hardening modes)
 // equivalent to setting the hardened mode.
 #  ifdef _LIBCPP_ENABLE_ASSERTIONS
 #    warning "_LIBCPP_ENABLE_ASSERTIONS is deprecated, please use _LIBCPP_ENABLE_HARDENED_MODE instead."
 #    if _LIBCPP_ENABLE_ASSERTIONS != 0 && _LIBCPP_ENABLE_ASSERTIONS != 1
 #      error "_LIBCPP_ENABLE_ASSERTIONS must be set to 0 or 1"
 #    endif
 #    if _LIBCPP_ENABLE_ASSERTIONS

libcxx/test/libcxx/assertions/modes/enabling_assertions_enables_hardened_mode.pass.cpp

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
-// TODO(hardening): remove in LLVM 18.
+// TODO(hardening): remove in LLVM 19.
 // This test ensures that enabling assertions now enables the hardened mode.
 
 // `check_assertion.h` is only available starting from C++11 and requires Unix headers.
 // UNSUPPORTED: c++03, !has-unix-headers
 // The ability to set a custom abort message is required to compare the assertion message.
 // XFAIL: availability-verbose_abort-missing
 // Debug mode is mutually exclusive with hardened mode.
 // UNSUPPORTED: libcpp-hardening-mode=debug