[clang] [Clang][NFC] Add test for CWG2285 "Issues with structured bindings" (PR #126421)

[via cfe-commits]

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@@ -136,7 +136,7 @@ namespace MultiDeclarator {
 
 namespace Template {
   int n[3];
-  // FIXME: There's no actual rule against this...
+  // Structured binding template is not allowed.
   template<typename T> auto [a, b, c] = n; // expected-error {{decomposition declaration template not supported}}
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cor3ntin wrote:

While we are there, can we change the diagnostic to `decomposition declaration cannot be a template` or something like that, not to give the impression it's a clang limitation?


https://github.com/llvm/llvm-project/pull/126421