[clang] [clang] Improve diagnostics for invalid named-universal-characters (PR #206326)

[Timm Baeder via cfe-commits]

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@@ -1085,6 +1085,26 @@ void clang::EscapeStringForDiagnostic(StringRef Str,
   }
 }
 
+/// DisplayCodePointForDiagnostic - Display CodePoint in U+NNNN notation,
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tbaederr wrote:

AFAIK this used to be either important for documentation generation or just a convention people followed but we don't do it anymore in modern documentation comments. It adds nothing to the generated documentation anyway: https://clang.llvm.org/doxygen/classclang_1_1Expr.html#a9d62f565d430947fdc3315fce592a532

https://github.com/llvm/llvm-project/pull/206326