[clang] Add support for referencable labels for attribute documentation (PR #118428)

[Aaron Ballman via cfe-commits]

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@@ -5178,6 +5178,9 @@ GetAttributeHeadingAndSpellings(const Record &Documentation,
 
 static void WriteDocumentation(const RecordKeeper &Records,
                                const DocumentationData &Doc, raw_ostream &OS) {
+  if (const StringRef label = Doc.Documentation->getValueAsString("Label");
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AaronBallman wrote:

Also: `label` -> `Label` per our usual naming rules.

https://github.com/llvm/llvm-project/pull/118428