[clang] [HLSL] make semantic matching case insensitive (PR #129773)

[Chris B via cfe-commits]

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@@ -141,6 +141,8 @@ void Parser::ParseHLSLAnnotations(ParsedAttributes &Attrs,
     return;
   }
 
+  II = PP.getIdentifierInfo(II->getName().lower());
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llvm-beanz wrote:

Can we keep the original identifier around and use that for the diagnostics so that the diagnostic text matches the capitalization in the source?

I often find myself copy and pasting error message text to then grep codebases, so it would be nice if we preserved the spelling.

https://github.com/llvm/llvm-project/pull/129773