--- a/llvm-project/clang/lib/AST/ItaniumMangle.cpp
+++ b/llvm-project/clang/lib/AST/ItaniumMangle.cpp
@@ -3048,11 +3048,7 @@ void CXXNameMangler::mangleNeonVectorType(const VectorType *T) {
 }

 void CXXNameMangler::mangleNeonVectorType(const DependentVectorType *T) {
-  DiagnosticsEngine &Diags = Context.getDiags();
-  unsigned DiagID = Diags.getCustomDiagID(
-      DiagnosticsEngine::Error,
-      "cannot mangle this dependent neon vector type yet");
-  Diags.Report(T->getAttributeLoc(), DiagID);
+  Out << "__unhandled_NeonVectorType";
 }

 static StringRef mangleAArch64VectorBase(const BuiltinType *EltType) {
@@ -3123,11 +3119,7 @@ void CXXNameMangler::mangleAArch64NeonVectorType(const VectorType *T) {
   Out << TypeName.length() << TypeName;
 }
 void CXXNameMangler::mangleAArch64NeonVectorType(const DependentVectorType *T) {
-  DiagnosticsEngine &Diags = Context.getDiags();
-  unsigned DiagID = Diags.getCustomDiagID(
-      DiagnosticsEngine::Error,
-      "cannot mangle this dependent neon vector type yet");
-  Diags.Report(T->getAttributeLoc(), DiagID);
+  Out << "__unhandled_AArch64NeonVectorType";
 }

 // GNU extension: vector types
@@ -3626,12 +3618,7 @@ recurse:
   case Expr::BuiltinBitCastExprClass:
   {
     if (!NullOut) {
-      // As bad as this diagnostic is, it's better than crashing.
-      DiagnosticsEngine &Diags = Context.getDiags();
-      unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
-                                       "cannot yet mangle expression type %0");
-      Diags.Report(E->getExprLoc(), DiagID)
-        << E->getStmtClassName() << E->getSourceRange();
+      Out << "__unhandled_expression";
     }
     break;
   }
@@ -3652,12 +3639,7 @@ recurse:

   // Even gcc-4.5 doesn't mangle this.
   case Expr::BinaryConditionalOperatorClass: {
-    DiagnosticsEngine &Diags = Context.getDiags();
-    unsigned DiagID =
-      Diags.getCustomDiagID(DiagnosticsEngine::Error,
-                "?: operator with omitted middle operand cannot be mangled");
-    Diags.Report(E->getExprLoc(), DiagID)
-      << E->getStmtClassName() << E->getSourceRange();
+    Out << "__unhandled_BinaryConditionalOperatorClass";
     break;
   }

@@ -3952,18 +3934,11 @@ recurse:
       Out << 'a';
       break;
     case UETT_VecStep: {
-      DiagnosticsEngine &Diags = Context.getDiags();
-      unsigned DiagID = Diags.getCustomDiagID(DiagnosticsEngine::Error,
-                                     "cannot yet mangle vec_step expression");
-      Diags.Report(DiagID);
+      Out << "__unhandled_VecStep";
       return;
     }
     case UETT_OpenMPRequiredSimdAlign: {
-      DiagnosticsEngine &Diags = Context.getDiags();
-      unsigned DiagID = Diags.getCustomDiagID(
-          DiagnosticsEngine::Error,
-          "cannot yet mangle __builtin_omp_required_simd_align expression");
-      Diags.Report(DiagID);
+      Out << "__unhandled_UETT_OpenMPRequiredSimdAlign";
       return;
     }
     }