[clang] Add clang atomic control options and attribute (PR #114841)

[Yaxun Liu via cfe-commits]

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@@ -3101,6 +3101,11 @@ class Parser : public CodeCompletionHandler {
   std::optional<AvailabilitySpec> ParseAvailabilitySpec();
   ExprResult ParseAvailabilityCheckExpr(SourceLocation StartLoc);
 
+  void ParseAtomicAttribute(IdentifierInfo &AttrName,
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yxsamliu wrote:

will use VariadicEnumArgument 

https://github.com/llvm/llvm-project/pull/114841