[clang] [Clang] emit -Wunused-variable warning for unused structured bindings without the [[maybe_unused]] attribute (PR #127061)

[Mariya Podchishchaeva via cfe-commits]

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@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -fsyntax-only -verify -std=c++2c -Wunused %s
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Fznamznon wrote:

NIT: why not c++26?
```suggestion
// RUN: %clang_cc1 -fsyntax-only -verify -std=c++26 -Wunused %s
```

https://github.com/llvm/llvm-project/pull/127061