[clang] [llvm] [clang][LLVM Demangler] Add a diagnostic that validates that all mang… (PR #111391)

[Viktoriia Bakalova via cfe-commits]

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@@ -384,4 +384,8 @@ def warn_hlsl_langstd_minimal :
   Warning<"support for HLSL language version %0 is incomplete, "
           "recommend using %1 instead">,
   InGroup<HLSLDXCCompat>;
+
+def warn_name_cannot_be_demangled : Warning<
+  "cannot demangle the name '%0'">,
+  InGroup<CXX20Compat>;
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VitaNuo wrote:

Added a new `Demangler` group.

https://github.com/llvm/llvm-project/pull/111391