[clang] [HLSL][Sema] Fixed Diagnostics that assumed only two arguments (PR #122772)

[Finn Plummer via cfe-commits]

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@@ -1688,13 +1688,21 @@ static bool CheckVectorElementCallArgs(Sema *S, CallExpr *TheCall) {
   auto *VecTyA = ArgTyA->getAs<VectorType>();
   SourceLocation BuiltinLoc = TheCall->getBeginLoc();
 
+  bool AllBArgAreVectors = true;
   for (unsigned i = 1; i < TheCall->getNumArgs(); ++i) {
     ExprResult B = TheCall->getArg(i);
     QualType ArgTyB = B.get()->getType();
     auto *VecTyB = ArgTyB->getAs<VectorType>();
-    if (VecTyA == nullptr && VecTyB == nullptr)
-      return false;
-
+    if (VecTyB == nullptr)
+      AllBArgAreVectors &= false;
+    if (VecTyA && VecTyB == nullptr) {
+      // Note: if we get here 'B' is scalar which
+      // requires a VectorSplat on ArgN
+      S->Diag(BuiltinLoc, diag::err_vec_builtin_non_vector)
+          << TheCall->getDirectCallee() << /*useAllTerminology*/ true
+          << SourceRange(A.get()->getBeginLoc(), B.get()->getEndLoc());
+      return true;
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inbelic wrote:

Okay, then I agree that it wouldn't be beneficial to do so.

https://github.com/llvm/llvm-project/pull/122772