102   inline bool IsNull() const { return type == NULL_SYMBOL; }  in IsNull()  function
921       if (!result.IsNull()) return result;  in FindByNameHelper()
931   if (result.IsNull() && pool->underlay_ != nullptr) {  in FindByNameHelper()
936   if (result.IsNull()) {  in FindByNameHelper()
1409   if (!result.IsNull()) return result.GetFile();  in FindFileContainingSymbol()
1417     if (!result.IsNull()) return result.GetFile();  in FindFileContainingSymbol()
1627   if (!result.IsNull() && !result.field_descriptor->is_extension()) {  in FindFieldByName()
1637   if (!result.IsNull()) {  in FindOneofByName()
1648   if (!result.IsNull() && result.field_descriptor->is_extension()) {  in FindExtensionByName()
1680   if (!result.IsNull()) {  in FindNestedTypeByName()
1691   if (!result.IsNull()) {  in FindEnumTypeByName()
1702   if (!result.IsNull()) {  in FindEnumValueByName()
1725   if (!result.IsNull()) {  in FindValueByName()
1745   if (!result.IsNull()) {  in FindMethodByName()
1755   if (!result.IsNull()) {  in FindMessageTypeByName()
1765   if (!result.IsNull()) {  in FindEnumTypeByName()
1776   if (!result.IsNull()) {  in FindEnumValueByName()
1786   if (!result.IsNull()) {  in FindServiceByName()
1796   if (!result.IsNull() && result.field_descriptor->is_extension()) {  in FindExtensionByName()
1897     if (!symbol.IsNull() && symbol.type != Symbol::PACKAGE) {  in IsSubSymbolOfBuiltType()
3709   if (result.IsNull() && pool->underlay_ != nullptr) {  in FindSymbolNotEnforcingDepsHelper()
3714   if (result.IsNull()) {  in FindSymbolNotEnforcingDepsHelper()
3745   if (result.IsNull()) return result;  in FindSymbol()
3827     if (!result.IsNull()) {  in LookupSymbolNoPlaceholder()
3835           if (result.IsNull()) {  in LookupSymbolNoPlaceholder()
3862   if (result.IsNull() && pool_->allow_unknown_) {  in LookupSymbol()
5583     if (extendee.IsNull()) {  in CrossLinkField()
5650     if (type.IsNull()) {  in CrossLinkField()
5677         if (type.IsNull()) {  in CrossLinkField()
5869   if (input_type.IsNull()) {  in CrossLinkMethod()
5889   if (output_type.IsNull()) {  in CrossLinkMethod()
6517   if (!symbol.IsNull() && symbol.type == Symbol::MESSAGE) {  in InterpretSingleOption()
6555       if (!symbol.IsNull() && symbol.type == Symbol::FIELD) {  in InterpretSingleOption()
7027         if (!symbol.IsNull() && symbol.type == Symbol::ENUM_VALUE) {  in SetOptionValue()
7449     if (!result.IsNull() && result.type == Symbol::MESSAGE) {  in OnceInternal()