[clang] [Clang] [AST] Fix placeholder return type name mangling for MSVC 1920+ / VS2019+ (PR #102848)

[Max Winkler via cfe-commits]

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@@ -408,6 +408,9 @@ class MicrosoftCXXNameMangler {
   void mangleSourceName(StringRef Name);
   void mangleNestedName(GlobalDecl GD);
 
+  void mangleAutoReturnType(QualType T, SourceRange Range,
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MaxEW707 wrote:

Argh you are correct. This is holdover from development code that I forgot to remove. I'll fix this.

https://github.com/llvm/llvm-project/pull/102848