[clang] [HLSL][RootSignature] Use "stringified" version for diagnostic output of punctuator tokens (PR #145827)

[Ashley Coleman via cfe-commits]

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@@ -18,3 +18,7 @@ void bad_root_signature_3() {}
 
 [RootSignature("DescriptorTable(), invalid")] // expected-error {{expected end of stream to denote end of parameters, or, another valid parameter of RootSignature}}
 void bad_root_signature_4() {}
+
+// expected-error at +1 {{expected ')' to denote end of parameters, or, another valid parameter of RootConstants}}
+[RootSignature("RootConstants(b0, num32BitConstants = 1, invalid)")]
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V-FEXrt wrote:

also I'm aware this comment isn't related to the actual fix of the PR so it's not blocking, just a side point

https://github.com/llvm/llvm-project/pull/145827