[clang] [clang] Look through alias templates when visiting dependent base classes (PR #223713)

[Corentin Jabot via cfe-commits]

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@@ -851,6 +793,11 @@ features cannot lower the translation-unit ABI level;
 
 ### Code Completion
 
+- Members inherited from a dependent base class that is named through an alias
+  template are now offered. Previously such a base was skipped entirely, so for
+  example a dependent `std::allocator<T>`, which derives from the alias template
+  `__allocator_base<T>`, offered none of the members it inherits.
+
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cor3ntin wrote:

```suggestion
- Members inherited from a dependent base class that is named through an alias
  template are suggested by code completion when relevant.

```

https://github.com/llvm/llvm-project/pull/223713