[clang] [StaticAnalyzer] Migrate away from PointerUnion::{is,get} (NFC) (PR #118421)

[Balazs Benics via cfe-commits]

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@@ -211,8 +211,8 @@ class MallocSizeofChecker : public Checker<check::ASTCodeBody> {
           continue;
 
         const TypeSourceInfo *TSI = nullptr;
-        if (CallRec.CastedExprParent.is<const VarDecl *>()) {
-          TSI = CallRec.CastedExprParent.get<const VarDecl *>()
+        if (isa<const VarDecl *>(CallRec.CastedExprParent)) {
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steakhal wrote:

We could use dyn_cast here I think.

https://github.com/llvm/llvm-project/pull/118421