[clang] [Clang] Correctly propagate type aliases' unexpanded flags up to lambda (PR #122875)

[Younan Zhang via cfe-commits]

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@@ -47,6 +49,10 @@ template <class = void> void f() {
     }(), ...);
   }(1, 2);
 
+  []<class... Is>(Is...) {
+    ([] { using T = ElementType<Is>; }(), ...);
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zyn0217 wrote:

Yes, that's exactly why the issue arises.

https://github.com/llvm/llvm-project/pull/122875