[analyzer] Remove cast inside dyn_cast.

llvm-svn: 162951

clang/lib/StaticAnalyzer/Checkers/BasicObjCFoundationChecks.cpp

@@ -737,7 +737,7 @@ ProgramStateRef assumeExprIsNonNull(const Expr *NonNullExpr,
                                     CheckerContext &C) {
   SVal Val = State->getSVal(NonNullExpr, C.getLocationContext());
   if (DefinedOrUnknownSVal *DV = dyn_cast<DefinedOrUnknownSVal>(&Val))
-    return State->assume(cast<DefinedOrUnknownSVal>(*DV), true);
+    return State->assume(*DV, true);
   return State;
 }