[clang] [Clang] remove redundant uses of dyn_cast (NFC) (PR #189106)

[Erich Keane via cfe-commits]

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@@ -1749,9 +1749,7 @@ PackIndexingExpr *PackIndexingExpr::Create(
 
 NamedDecl *PackIndexingExpr::getPackDecl() const {
   if (auto *D = dyn_cast<DeclRefExpr>(getPackIdExpression()); D) {
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erichkeane wrote:

I half expected to be the author on that one :D  Would be nice to clean that up at one point, but I see its already merged so asking as a drive-by isn't really going to happen :) 

https://github.com/llvm/llvm-project/pull/189106