[clang] [clang] add test verifying DR242 behavior (PR #201441)

[Vlad Serebrennikov via cfe-commits]

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@@ -695,6 +695,37 @@ namespace cwg241 { // cwg241: 9
   }
 } // namespace cwg241
 
+namespace cwg242 { // cwg242: yes
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Endilll wrote:

Use Compiler Explorer to figure out what was the first version of Clang that exhibits the expected behavior. Also see https://github.com/llvm/llvm-project/pull/195490#pullrequestreview-4216710625.

https://github.com/llvm/llvm-project/pull/201441