[clang] [Clang][Sema] Revisit the fix for the lambda within a type alias template decl (PR #89934)

[Matheus Izvekov via cfe-commits]

================
@@ -91,15 +91,84 @@ void bar() {
 
 namespace GH82104 {
 
-template <typename, typename...> int Zero = 0;
+template <typename, typename... D> int Value = sizeof...(D);
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mizvekov wrote:

```suggestion
template <typename, typename... D> constexpr int Value = sizeof...(D);
```

https://github.com/llvm/llvm-project/pull/89934