[clang] [HLSL] Implement TextureCube resource type (PR #218520)

[Helena Kotas via cfe-commits]

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@@ -696,15 +712,17 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
     Args.push_back(HandleOp);
     Args.push_back(SamplerOp);
     Args.push_back(CoordOp);
-    Args.push_back(emitHlslOffset(*this, E, 3, getOffsetType(CGM, RT)));
+    const unsigned OffsetIdx = 3;
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hekota wrote:

```suggestion
    constexpr unsigned OffsetIdx = 3;
```
These should probably be constexpr.

https://github.com/llvm/llvm-project/pull/218520