fixup! poor diagnostic due to overloading in extern "C" block #80235

Author: s-watanabe314

clang/docs/ReleaseNotes.rst

@@ -261,6 +261,8 @@ Improvements to Clang's diagnostics
   compilation speed with modules. This warning is disabled by default and it needs
   to be explicitly enabled or by ``-Weverything``.
 
+- Improved diagnostics when trying to overload a function in extern "C". (#GH80235)
+
 Improvements to Clang's time-trace
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