[clang] [HLSL] add IsLineVectorLayoutCompatible type trait (PR #113730)

[Finn Plummer via cfe-commits]

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@@ -2163,6 +2163,49 @@ static void BuildFlattenedTypeList(QualType BaseTy,
   }
 }
 
+bool SemaHLSL::IsLineVectorLayoutCompatibleType(clang::QualType QT) {
+  if (QT.isNull())
+    return false;
+
+  llvm::SmallVector<QualType, 16> QTTypes;
+  BuildFlattenedTypeList(QT, QTTypes);
+
+  QualType FirstQT = QTTypes[0];
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inbelic wrote:

Maybe we could add an assert on the vector size or a check with `llvm_unreachable` when size is 0

https://github.com/llvm/llvm-project/pull/113730