[NFC][CLANG] Fix nullptr dereference issue in ConvertQualTypeToKind()

[Manna]

Summary

This patch uses castAs instead of getAs which will assert if the type doesn't match in ConvertQualTypeToKind(clang::​ASTContext const &, clang::​QualType).

[Manna]

Thank you @erichkeane for reviews!

clang/lib/Interpreter/Value.cpp

static Value::Kind ConvertQualTypeToKind(const ASTContext &Ctx, QualType QT) {
 
   if (const auto *ET = QT->getAs<EnumType>())
     QT = ET->getDecl()->getIntegerType();
 
   const auto *BT = QT->getAs<BuiltinType>();
   if (!BT || BT->isNullPtrType())
     return Value::K_PtrOrObj;
 
-  switch (QT->getAs<BuiltinType>()->getKind()) {
+  switch (QT->castAs<BuiltinType>()->getKind()) {
   default:
     assert(false && "Type not supported");
     return Value::K_Unspecified;
 #define X(type, name)                                                          \
   case BuiltinType::name:                                                      \
     return Value::K_##name;
     REPL_BUILTIN_TYPES
 #undef X