[libc++] Implement P2273R3 (`constexpr` `unique_ptr`)

Reviewed By: mordante, #libc

Differential Revision: https://reviews.llvm.org/D131315

NOKEYCHECK=True
GitOrigin-RevId: 30dadaa2eb499395f5bef44b9e1a18db6360ad1f
diff --git a/docs/FeatureTestMacroTable.rst b/docs/FeatureTestMacroTable.rst
index 8860578..8d38beb 100644
--- a/docs/FeatureTestMacroTable.rst
+++ b/docs/FeatureTestMacroTable.rst
@@ -312,6 +312,8 @@
     ------------------------------------------------- -----------------
     ``__cpp_lib_constexpr_cmath``                     *unimplemented*
     ------------------------------------------------- -----------------
+    ``__cpp_lib_constexpr_memory``                    ``202202L``
+    ------------------------------------------------- -----------------
     ``__cpp_lib_constexpr_typeinfo``                  *unimplemented*
     ------------------------------------------------- -----------------
     ``__cpp_lib_forward_like``                        ``202207L``
diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index 5c15852..9831d03 100644
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -40,6 +40,7 @@
 - P2499R0 - ``string_view`` range constructor should be ``explicit``
 - P2417R2 - A more constexpr bitset
 - P2445R1 - ``std::forward_like``
+- P2273R3 - Making ``std::unique_ptr`` constexpr
 
 Improvements and New Features
 -----------------------------
diff --git a/docs/Status/Cxx2b.rst b/docs/Status/Cxx2b.rst
index de89162..1537494 100644
--- a/docs/Status/Cxx2b.rst
+++ b/docs/Status/Cxx2b.rst
@@ -37,6 +37,10 @@
    :header-rows: 1
    :widths: auto
 
+.. note::
+
+   .. [#note-P2273] P2273: ``make_unique_for_overwrite`` isn't done yet since `P1020` hasn't been implemented yet.
+
 .. _issues-status-cxx2b:
 
 Library Working Group Issues Status
diff --git a/docs/Status/Cxx2bPapers.csv b/docs/Status/Cxx2bPapers.csv
index cbf0db4..d4d1176 100644
--- a/docs/Status/Cxx2bPapers.csv
+++ b/docs/Status/Cxx2bPapers.csv
@@ -44,7 +44,7 @@
 "`P1206R7 <https://wg21.link/P1206R7>`__","LWG","``ranges::to``: A function to convert any range to a container","February 2022","",""
 "`P1413R3 <https://wg21.link/P1413R3>`__","LWG","Deprecate ``std::aligned_storage`` and ``std::aligned_union``","February 2022","",""
 "`P2255R3 <https://wg21.link/P2255R3>`__","LWG","A type trait to detect reference binding to temporary","February 2022","",""
-"`P2273R3 <https://wg21.link/P2273R3>`__","LWG","Making ``std::unique_ptr`` constexpr","February 2022","",""
+"`P2273R3 <https://wg21.link/P2273R3>`__","LWG","Making ``std::unique_ptr`` constexpr","February 2022","|Partial| [#note-P2273]_","16.0"
 "`P2387R3 <https://wg21.link/P2387R3>`__","LWG","Pipe support for user-defined range adaptors","February 2022","",""
 "`P2440R1 <https://wg21.link/P2440R1>`__","LWG","``ranges::iota``, ``ranges::shift_left`` and ``ranges::shift_right``","February 2022","",""
 "`P2441R2 <https://wg21.link/P2441R2>`__","LWG","``views::join_view``","February 2022","",""