Update release notes

Author: whiteio

clang/docs/ReleaseNotes.rst

@@ -641,6 +641,20 @@ Improvements to Clang's diagnostics
 
 - Clang now diagnoses dangling references for C++20's parenthesized aggregate initialization (#101957).
 
+- Fixed a bug where Clang would not emit ``-Wunused-private-field`` warnings when an unrelated class 
+  defined a defaulted comparison operator (#GH116270).
+
+  .. code-block:: c++
+
+    class A {
+    private:
+      int a; // warning: private field 'a' is not used, no diagnostic previously
+    };
+
+    class C {
+      bool operator==(const C&) = default;
+    };
+
 Improvements to Clang's time-trace
 ----------------------------------
 

clang/test/SemaCXX/warn-unused-private-field.cpp

@@ -40,13 +40,6 @@ class FriendEqDefaultCompareOutOfClass {
 
 bool operator==(const FriendEqDefaultCompareOutOfClass &, const FriendEqDefaultCompareOutOfClass &) = default;
 
-class UnusedConstPrivateField {
-public:
-    UnusedConstPrivateField() : unused_(0) {}
-private:
-    const int unused_; // expected-warning{{private field 'unused_' is not used}}
-};
-
 class HasUnusedField {
   int unused_; // expected-warning{{private field 'unused_' is not used}}
 };