[libc++] Enable [[nodiscard]] extensions by default
Adding `[[nodiscard]]` to functions is a conforming extension and done extensively in the MSVC STL.
Reviewed By: ldionne, EricWF, #libc
Spies: #libc_vendors, cjdb, mgrang, jloser, libcxx-commits
Differential Revision: https://reviews.llvm.org/D128267
NOKEYCHECK=True
GitOrigin-RevId: 3c355e2881887fea6f4b31e26b68aefa4d216fd0
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index fda4b69..8d11c1b 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -75,7 +75,7 @@
- ``_LIBCPP_ENABLE_NODISCARD`` and ``_LIBCPP_DISABLE_NODISCARD_AFTER_CXX17`` are no longer respected.
Any standards-required ``[[nodiscard]]`` applications in C++20 are now always enabled. Any extended applications
- can now be enabled by defining ``_LIBCPP_ENABLE_NODISCARD_EXT``.
+ are now enabled by default and can be disabled by defining ``_LIBCPP_DISABLE_NODISCARD_EXT``.
ABI Affecting Changes
---------------------
diff --git a/docs/UsingLibcxx.rst b/docs/UsingLibcxx.rst
index e45afd6..59a1e4b 100644
--- a/docs/UsingLibcxx.rst
+++ b/docs/UsingLibcxx.rst
@@ -248,8 +248,8 @@
replacement scenarios from working, e.g. replacing `operator new` and
expecting a non-replaced `operator new[]` to call the replaced `operator new`.
-**_LIBCPP_ENABLE_NODISCARD_EXT**:
- This macro allows the library to apply ``[[nodiscard]]`` to entities as an extension.
+**_LIBCPP_DISABLE_NODISCARD_EXT**:
+ This macro disables library-extensions of ``[[nodiscard]]``.
See :ref:`Extended Applications of [[nodiscard]] <nodiscard extension>` for more information.
**_LIBCPP_DISABLE_DEPRECATION_WARNINGS**:
@@ -340,8 +340,8 @@
liberal application of ``[[nodiscard]]``.
For this reason libc++ provides an extension that does just that! The
-extension must be enabled by defining ``_LIBCPP_ENABLE_NODISCARD_EXT``. The extended
-applications of ``[[nodiscard]]`` takes two forms:
+extension is enabled by default and can be disabled by defining ``_LIBCPP_DISABLE_NODISCARD_EXT``.
+The extended applications of ``[[nodiscard]]`` takes two forms:
1. Backporting ``[[nodiscard]]`` to entities declared as such by the
standard in newer dialects, but not in the present one.