[clang] Raise an error on namespace aliases with qualified names. (PR #86122)

[via cfe-commits]

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@@ -268,6 +268,8 @@ def err_expected_semi_after_namespace_name : Error<
   "expected ';' after namespace name">;
 def err_unexpected_namespace_attributes_alias : Error<
   "attributes cannot be specified on namespace alias">;
+def err_unexpected_qualified_namespace_alias : Error<
+  "unexpected nested name specifier in namespace alias definition">;
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Sirraide wrote:

I’m not sure how many people would know what a ‘nested name specifier’ is—or at least it requires a bit of thinking. Maybe something like ‘namespace alias must be a single identifier’ would be a bit more obvious?

https://github.com/llvm/llvm-project/pull/86122