[clang-tools-extra] [clang-tidy][NFC] Apply llvm-redundant-casting check (PR #214024)

[Yanzuo Liu via cfe-commits]

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@@ -351,7 +351,7 @@ class RenamerClangTidyVisitor
     if (!Decl)
       return true;
 
-    if (const auto *ClassDecl = dyn_cast<TemplateDecl>(Decl))
+    if (const auto *ClassDecl = Decl)
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zwuis wrote:

`Decl` is always non-null here.

https://github.com/llvm/llvm-project/pull/214024