[clang] [Clang] raise extension warning for unknown namespaced attributes (PR #120925)

[Oleksandr T. via cfe-commits]

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@@ -166,7 +166,8 @@ getScopeFromNormalizedScopeName(StringRef ScopeName) {
       .Case("hlsl", AttributeCommonInfo::Scope::HLSL)
       .Case("msvc", AttributeCommonInfo::Scope::MSVC)
       .Case("omp", AttributeCommonInfo::Scope::OMP)
-      .Case("riscv", AttributeCommonInfo::Scope::RISCV);
+      .Case("riscv", AttributeCommonInfo::Scope::RISCV)
+      .Default(AttributeCommonInfo::Scope::NONE);
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a-tarasyuk wrote:

I added `UNKNOWN` kind as the default case

https://github.com/llvm/llvm-project/pull/120925