[clang] Use cast_or_null instead of cast (PR #93749)

[Younan Zhang via cfe-commits]

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@@ -2408,9 +2408,11 @@ Expr *VarDecl::getInit() {
     return cast<Expr>(S);
 
   auto *Eval = getEvaluatedStmt();
-  return cast<Expr>(Eval->Value.isOffset()
-                        ? Eval->Value.get(getASTContext().getExternalSource())
-                        : Eval->Value.get(nullptr));
+
+  return cast_or_null<Expr>(
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zyn0217 wrote:

nit: Prefer `cast_if_present`.

https://github.com/llvm/llvm-project/pull/93749