[clang] [Clang] Improve diagnostics to show the correct position for `[[maybe_unused]]` before a using-alias (PR #223910)

[Shafik Yaghmour via cfe-commits]

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@@ -740,7 +749,7 @@ Parser::DeclGroupPtrTy Parser::ParseUsingDeclaration(
       return nullptr;
     }
 
-    ProhibitAttributes(PrefixAttrs);
+    ProhibitAttributes(PrefixAttrs, Tok.getLocation());
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shafik wrote:

It looks like we don't use this argument in most other places in `ParseDeclCXX.cpp`, should we or will this not work for the other cases?

https://github.com/llvm/llvm-project/pull/223910