[clang] [HLSL] Add a warning for implicit bindings (PR #135909)

[Justin Bogner via cfe-commits]

================
@@ -3278,6 +3284,9 @@ void SemaHLSL::processExplicitBindingsOnDecl(VarDecl *VD) {
           << static_cast<int>(RT);
     }
   }
+
+  if (!HasBinding && VD->getType()->isHLSLResourceRecord())
+    SemaRef.Diag(VD->getLocation(), diag::warn_hlsl_implicit_binding);
----------------
bogner wrote:

`ActOnFinishBuffer` executes when finishing a `cbuffer {...}` or `tbuffer {...}` block. The word "buffer" in that function name specifically refers to those blocks, not the various resource types that happen to be buffers. So the logic here is needed for the warnings on things like `RWBuffer<T> x;`

https://github.com/llvm/llvm-project/pull/135909