[clang] [HLSL] Support packoffset attribute in AST (PR #89836)

[Helena Kotas via cfe-commits]

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@@ -7314,6 +7314,47 @@ static void handleHLSLSV_DispatchThreadIDAttr(Sema &S, Decl *D,
   D->addAttr(::new (S.Context) HLSLSV_DispatchThreadIDAttr(S.Context, AL));
 }
 
+static void handleHLSLPackOffsetAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+  if (!isa<VarDecl>(D)) {
+    S.Diag(AL.getLoc(), diag::err_hlsl_attr_invalid_ast_node)
+        << AL << "cbuffer constant";
+    return;
+  }
+  auto *BufDecl = dyn_cast<HLSLBufferDecl>(D->getDeclContext());
+  if (!BufDecl) {
+    S.Diag(AL.getLoc(), diag::err_hlsl_attr_invalid_ast_node)
+        << AL << "cbuffer constant";
+    return;
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hekota wrote:

Both conditions issue the same diagnostic and `BufDecl` does not seem to be used after this. Maybe merge them?

`if (!isa<VarDecl>(D) || !isa<HLSLBufferDecl>(D->getDeclContext()) {`

https://github.com/llvm/llvm-project/pull/89836