[clang] [Clang][Sema] Reject invalid member using-declaration whose nested-name-specifier doesn't refer to a base class of the current class in C++98 mode (PR #143492)

[Vlad Serebrennikov via cfe-commits]

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@@ -36,6 +36,13 @@ namespace cwg400 { // cwg400: 2.7
   // expected-error at -1 {{member 'a' found in multiple base classes of different types}}
   //   expected-note@#cwg400-A {{member type 'cwg400::A::a' found by ambiguous name lookup}}
   //   expected-note@#cwg400-B {{member type 'cwg400::B::a' found by ambiguous name lookup}}
+  struct F : A {};
+  struct G : A {
+    using G::A;
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Endilll wrote:

```suggestion
    using G::a;
```
Did you mean lowercase `a`?

https://github.com/llvm/llvm-project/pull/143492