[clang] [Parser][NFC] Move the core parsing of an attribute into a separate method (PR #107300)

[Erich Keane via cfe-commits]

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@@ -2943,6 +2943,9 @@ class Parser : public CodeCompletionHandler {
     return false;
   }
 
+  bool ParseGNUSingleAttribute(ParsedAttributes &Attrs, SourceLocation &EndLoc,
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erichkeane wrote:

I don't have a preference for any of the 3 names, but a comment explaining WHERE it is in the source would be very helpful.

That said, what makes this GNU specific?  Once we're inside of the braces/bracket/etc, I'd expect there to be only slightly minor differences between the three attribute parsings, so I'd expect them to be a single function with a few special cases (std attributes with an optional namespace, etc).

https://github.com/llvm/llvm-project/pull/107300