[clang] [Attributes] Support Attributes being declared as supporting an experimental late parsing mode "extension" (PR #88596)

[Yeoul Na via cfe-commits]

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@@ -89,13 +89,23 @@ static StringRef normalizeAttrName(StringRef Name) {
   return Name;
 }
 
-/// isAttributeLateParsed - Return true if the attribute has arguments that
-/// require late parsing.
-static bool isAttributeLateParsed(const IdentifierInfo &II) {
+/// returns true iff attribute is annotated with `LateAttrParseExperimentalExt`
+/// in `Attr.td`.
+static bool IsAttributeLateParsedExperimentalExt(const IdentifierInfo &II) {
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rapidsna wrote:

Nit: should we make it consistent `IsAttributeLateParsedExperimentalExt` and `isAttributeLateParsedStandard`? One starts with capital I and the other starts with lower-case i.

https://github.com/llvm/llvm-project/pull/88596