[clang] [HLSL] Implement '__builtin_hlsl_is_intangible' type trait (PR #104544)

[Greg Roth via cfe-commits]

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@@ -1154,3 +1156,70 @@ bool SemaHLSL::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   }
   return false;
 }
+
+static bool calculateIsIntangibleType(QualType Ty) {
+  Ty = Ty->getCanonicalTypeUnqualified();
+  if (Ty->isBuiltinType())
+    return Ty->isHLSLSpecificType();
+
+  llvm::SmallVector<QualType, 8> TypesToScan;
+  TypesToScan.push_back(Ty);
+  while (!TypesToScan.empty()) {
+    QualType T = TypesToScan.pop_back_val();
+    assert(T == T->getCanonicalTypeUnqualified() && "expected sugar-free type");
+    assert(!isa<MatrixType>(T) && "Matrix types not yet supported in HLSL");
+
+    if (const auto *AT = dyn_cast<ConstantArrayType>(T)) {
+      QualType ElTy = AT->getElementType()->getCanonicalTypeUnqualified();
+      if (ElTy->isBuiltinType())
+        return ElTy->isHLSLSpecificType();
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pow2clk wrote:

This duplicates the [comment ](https://github.com/llvm/llvm-project/pull/104544#discussion_r1731610819) Justin made 

https://github.com/llvm/llvm-project/pull/104544