[clang] [clang-cl] Fix value of __FUNCTION__ in MSVC mode. (PR #84014)

[Aaron Ballman via cfe-commits]

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@@ -855,7 +868,17 @@ void DeclPrinter::VisitFunctionDecl(FunctionDecl *D) {
         Out << Proto << " -> ";
         Proto.clear();
       }
-      AFT->getReturnType().print(Out, Policy, Proto);
+      if (!Policy.SuppressTagKeyword && Policy.SuppressScope &&
+          !Policy.SuppressUnwrittenScope) {
+        AddPrefix(Policy, AFT->getReturnType(), Out);
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AaronBallman wrote:

This check is duplicated in `AddPrefix()`, same below (probably can remove the check from `AddPrefix()` or turn it into an assertion).

https://github.com/llvm/llvm-project/pull/84014