[clang] [HLSL][RootSignature] Define and integrate rootsig clang attr and decl (PR #137690)

[Finn Plummer via cfe-commits]

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@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple dxil-pc-shadermodel6.3-library -x hlsl -o - %s -verify
+
+// Attr test
+
+[RootSignature()] // expected-error {{expected string literal as argument of 'RootSignature' attribute}}
+void bad_root_signature_0() {}
+
+// expected-error at +2 {{expected ')'}}
+// expected-note at +1 {{to match this '('}}
+[RootSignature("", "")]
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inbelic wrote:

The location here points to the comma

https://github.com/llvm/llvm-project/pull/137690