[clang] [Clang][Sema] Fix Wswitch-default bad warning in template (PR #76007)

[Shafik Yaghmour via cfe-commits]

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@@ -0,0 +1,27 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 -Wswitch-default %s
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shafik wrote:

I think we can add these test to `clang/test/Sema/switch-default.c`

https://github.com/llvm/llvm-project/pull/76007