[libc++] Implement P2438R2 (std::string::substr() &&)
This doesn't affect our ABI because `std::string::substr()` isn't in the dylib and the mangling of `substr() const` and `substr() const&` are different.
Reviewed By: ldionne, Mordante, var-const, avogelsgesang, #libc
Spies: arphaman, huixie90, libcxx-commits
Differential Revision: https://reviews.llvm.org/D131668
NOKEYCHECK=True
GitOrigin-RevId: 29378ab24b98137b4959034a0882c3bbd97c46e4
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index d10fdde..abcebeb 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -46,6 +46,7 @@
``from_chars`` for Integral Types in ``<charconv>`` Header
- P0220R1 - Adopt Library Fundamentals V1 TS Components for C++17
- P0482R6 - char8_t: A type for UTF-8 characters and strings
+- P2438R2 - ``std::string::substr() &&``
Improvements and New Features
-----------------------------