[clang] [clang][ThreadSafety] Enable late parse for all capabilities, under the experimental flag (PR #212615)

[Jameson Nash via cfe-commits]

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@@ -195,6 +195,25 @@ bool Parser::ParseSingleGNUAttribute(ParsedAttributes &Attrs,
   // Handle attributes with arguments that require late parsing.
   LateParsedAttribute *LA =
       new LateParsedAttribute(this, *AttrName, AttrNameLoc);
+
+  // Keep the innermost prototype's parameters available in case they are needed
+  // by late-parsing attributes. A function keeps its own parameters in scope,
+  // so skip it; a parameter of function type is adjusted to a pointer, so keep
+  // it.
+  if (D && (!D->isFunctionDeclarator() || D->isPrototypeContext())) {
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vtjnash wrote:

You've got a good eye for asking the right questions here. Yes, that was indeed necessary too.

https://github.com/llvm/llvm-project/pull/212615