[clang] [Clang][Sema] Diagnose friend declarations with enum elaborated-type-specifier in all language modes (PR #80171)

[Vlad Serebrennikov via cfe-commits]

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@@ -107,6 +107,7 @@ namespace dr1638 { // dr1638: 3.1
   struct B {
     friend enum class A<unsigned>::E;
     // since-cxx11-error at -1 {{reference to enumeration must use 'enum' not 'enum class'}}
+    // since-cxx11-error at -2 {{cannot be a friend}}
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Endilll wrote:

Can you match the whole diagnostic message, like the rest of the tests in the file?

https://github.com/llvm/llvm-project/pull/80171