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

[Justin Bogner via cfe-commits]

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@@ -0,0 +1,28 @@
+// RUN: %clang_cc1 -Wno-error=hlsl-implicit-binding -triple dxil-pc-shadermodel6.3-library -x hlsl -o - -fsyntax-only %s -verify
+
+// expected-warning at +1 {{resource has implicit register binding}}
+cbuffer cb0 {
+  int a;
+}
+
+// No warning - this is an element of the $Globals buffer not it's own binding.
+float b;
+
+// expected-warning at +1 {{resource has implicit register binding}}
+RWBuffer<int> c;
+
+// No warning - explicit binding.
+RWBuffer<float> d : register(u0);
+
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bogner wrote:

This can't be tested util #135287 goes in, but it should warn. I added a commented out test and a `TODO` comment.

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