Linkage errors when using SWIG, protobuf - c++

Question

I'm trying to use SWIG so that I can call C++ code from Go.
I want to use SWIG so that it can generate me wrapper code. The C++ code in question is generated by the protobuf compiler.
I have two hello.i files hello.i and protobuf.i:
protbuf.i
#define GOOGLE_PROTOBUF_VERSION 3021008
#define GOOGLE_PROTOBUF_MIN_PROTOC_VERSION 3021000
hello.i
%module example
%include "protobuf.i"
%{
#include "hello.pb.h"
#include "hello.gen.h"
%}
#include "hello.pb.h"
#include "hello.gen.h"
namespace example {
void handle_Person(example::Person& m, unsigned char* friends);
}
I am able to compile this with the SWIG command swig -go -cgo -c++ hello.i and it generates Go and _wrap.cc file.
Then I create a shared library with the following sequence of commands:
g++ -fPIC -c hello_wrap.cxx hello.pb.cc hello.gen.cc -ldl -lprotobuf -lprotoc -L${MY_PROJECT}/protobuf -L${MY_PROJECT}/protobuf/third_party/abseil-cpp/absl -L${MY_PROJECT}/protobuf/third_party/utf8_range
g++ -shared -o libhellowrap.so hello_wrap.o hello.gen.o hello.pb.o -ldl -lprotobuf -lprotoc -L${MY_PROJECT}/protobuf -L${MY_PROJECT}/protobuf/third_party/abseil-cpp/absl -L${MY_PROJECT}/protobuf/third_party/utf8_range
Now I want to use this in Go so I create a main.go file:
package main
/*
#cgo CFLAGS: -I/my_project/example
#cgo LDFLAGS: -L/my_project/example -lhellowrap -ldl -lstdc++
#include <stdlib.h>
*/
import (
"C"
"fmt"
"my_project/example"
)
func main() {
var p example.SwigcptrExample_Person
p = example.SwigcptrExample_Person(uintptr(int32(2000)))
friends := make([]byte, 5)
example.Handle_Person(p, &friends[0])
fmt.Println("New Friends: ", friends)
}
Then I run this main.go file and the following linkage errors occur:
# command-line-arguments
/usr/local/go/pkg/tool/linux_amd64/link: running g++ failed: exit status 1
/tmp/go-link-96276495/000017.o: In function `example::Person::MergeImpl(google::protobuf::Message&, google::protobuf::Message const&)':
/usr/local/include/google/protobuf/metadata_lite.h:183: undefined reference to `void google::protobuf::internal::InternalMetadata::DoMergeFrom<google::protobuf::UnknownFieldSet>(google::protobuf::UnknownFieldSet const&)'
/tmp/go-link-96276495/000017.o: In function `example::Person::MergeImpl(google::protobuf::Message&, google::protobuf::Message const&)':
/my_project/example/hello.pb.cc:265: undefined reference to `google::protobuf::internal::LogMessage::LogMessage(google::protobuf::LogLevel, char const*, int)'
/my_project/example/hello.pb.cc:265: undefined reference to `google::protobuf::internal::LogMessage::operator<<(char const*)'
/my_project/example/hello.pb.cc:265: undefined reference to `google::protobuf::internal::LogFinisher::operator=(google::protobuf::internal::LogMessage&)'
/my_project/example/hello.pb.cc:265: undefined reference to `google::protobuf::internal::LogMessage::~LogMessage()'
/tmp/go-link-96276495/000017.o: In function `example::Person::_InternalSerialize(unsigned char*, google::protobuf::io::EpsCopyOutputStream*) const':
/usr/local/include/google/protobuf/io/coded_stream.h:674: undefined reference to `google::protobuf::io::EpsCopyOutputStream::EnsureSpaceFallback(unsigned char*)'
/tmp/go-link-96276495/000017.o: In function `example::Person::_InternalParse(char const*, google::protobuf::internal::ParseContext*)':
/usr/local/include/google/protobuf/parse_context.h:567: undefined reference to `google::protobuf::internal::VarintParseSlow32(char const*, unsigned int)'
/usr/local/include/google/protobuf/parse_context.h:228: undefined reference to `google::protobuf::internal::LogMessage::LogMessage(google::protobuf::LogLevel, char const*, int)'
/usr/local/include/google/protobuf/parse_context.h:228: undefined reference to `google::protobuf::internal::LogMessage::operator<<(char const*)'
/usr/local/include/google/protobuf/parse_context.h:228: undefined reference to `google::protobuf::internal::LogFinisher::operator=(google::protobuf::internal::LogMessage&)'
/usr/local/include/google/protobuf/parse_context.h:228: undefined reference to `google::protobuf::internal::LogMessage::~LogMessage()'
/usr/local/include/google/protobuf/parse_context.h:239: undefined reference to `google::protobuf::internal::EpsCopyInputStream::DoneFallback(int, int)'
/tmp/go-link-96276495/000017.o: In function `example::Person::_InternalParse(char const*, google::protobuf::internal::ParseContext*)':
/my_project/example/hello.pb.cc:198: undefined reference to `google::protobuf::internal::UnknownFieldParse(unsigned long, google::protobuf::UnknownFieldSet*, char const*, google::protobuf::internal::ParseContext*)'
/tmp/go-link-96276495/000017.o: In function `example::Person::_InternalParse(char const*, google::protobuf::internal::ParseContext*)':
/usr/local/include/google/protobuf/parse_context.h:658: undefined reference to `google::protobuf::internal::ReadTagFallback(char const*, unsigned int)'
/usr/local/include/google/protobuf/parse_context.h:231: undefined reference to `google::protobuf::internal::LogMessage::LogMessage(google::protobuf::LogLevel, char const*, int)'
/usr/local/include/google/protobuf/parse_context.h:231: undefined reference to `google::protobuf::internal::LogMessage::operator<<(char const*)'
/usr/local/include/google/protobuf/parse_context.h:231: undefined reference to `google::protobuf::internal::LogFinisher::operator=(google::protobuf::internal::LogMessage&)'
/usr/local/include/google/protobuf/parse_context.h:231: undefined reference to `google::protobuf::internal::LogMessage::~LogMessage()'
/tmp/go-link-96276495/000017.o: In function `example::Person::_InternalParse(char const*, google::protobuf::internal::ParseContext*)':
/usr/local/include/google/protobuf/metadata_lite.h:159: undefined reference to `google::protobuf::UnknownFieldSet* google::protobuf::internal::InternalMetadata::mutable_unknown_fields_slow<google::protobuf::UnknownFieldSet>()'
/tmp/go-link-96276495/000017.o: In function `example::Person::~Person()':
/usr/local/include/google/protobuf/message.h:245: undefined reference to `vtable for google::protobuf::Message'
/usr/local/include/google/protobuf/message.h:245: undefined reference to `google::protobuf::MessageLite::~MessageLite()'
/tmp/go-link-96276495/000017.o: In function `example::Person::~Person()':
/usr/local/include/google/protobuf/metadata_lite.h:113: undefined reference to `google::protobuf::Arena* google::protobuf::internal::InternalMetadata::DeleteOutOfLineHelper<google::protobuf::UnknownFieldSet>()'
/tmp/go-link-96276495/000017.o: In function `example::Person::~Person()':
/my_project/example/hello.pb.cc:153: undefined reference to `google::protobuf::internal::LogMessage::LogMessage(google::protobuf::LogLevel, char const*, int)'
/my_project/example/hello.pb.cc:153: undefined reference to `google::protobuf::internal::LogMessage::operator<<(char const*)'
/my_project/example/hello.pb.cc:153: undefined reference to `google::protobuf::internal::LogFinisher::operator=(google::protobuf::internal::LogMessage&)'
/my_project/example/hello.pb.cc:153: undefined reference to `google::protobuf::internal::LogMessage::~LogMessage()'
/tmp/go-link-96276495/000017.o: In function `example::Person::Person(google::protobuf::Arena*, bool)':
/usr/local/include/google/protobuf/message_lite.h:432: undefined reference to `vtable for google::protobuf::MessageLite'
/tmp/go-link-96276495/000017.o: In function `example::Person::Person(google::protobuf::Arena*, bool)':
/usr/local/include/google/protobuf/metadata_lite.h:78: undefined reference to `google::protobuf::internal::LogMessage::LogMessage(google::protobuf::LogLevel, char const*, int)'
/usr/local/include/google/protobuf/metadata_lite.h:78: undefined reference to `google::protobuf::internal::LogMessage::operator<<(char const*)'
/usr/local/include/google/protobuf/metadata_lite.h:78: undefined reference to `google::protobuf::internal::LogFinisher::operator=(google::protobuf::internal::LogMessage&)'
/usr/local/include/google/protobuf/metadata_lite.h:78: undefined reference to `google::protobuf::internal::LogMessage::~LogMessage()'
/tmp/go-link-96276495/000017.o: In function `example::Person::Person(example::Person const&)':
/usr/local/include/google/protobuf/metadata_lite.h:183: undefined reference to `void google::protobuf::internal::InternalMetadata::DoMergeFrom<google::protobuf::UnknownFieldSet>(google::protobuf::UnknownFieldSet const&)'
/tmp/go-link-96276495/000017.o: In function `example::Person* google::protobuf::Arena::CreateMaybeMessage<example::Person>(google::protobuf::Arena*)':
/usr/local/include/google/protobuf/arena.h:309: undefined reference to `google::protobuf::Arena::Allocate(unsigned long)'
/tmp/go-link-96276495/000017.o: In function `example::Person::Clear()':
/usr/local/include/google/protobuf/metadata_lite.h:190: undefined reference to `void google::protobuf::internal::InternalMetadata::DoClear<google::protobuf::UnknownFieldSet>()'
/tmp/go-link-96276495/000017.o: In function `example::Person::_InternalSerialize(unsigned char*, google::protobuf::io::EpsCopyOutputStream*) const':
/my_project/example/hello.pb.cc:228: undefined reference to `google::protobuf::internal::WireFormat::InternalSerializeUnknownFieldsToArray(google::protobuf::UnknownFieldSet const&, unsigned char*, google::protobuf::io::EpsCopyOutputStream*)'
/tmp/go-link-96276495/000017.o: In function `example::Person::ByteSizeLong() const':
/my_project/example/hello.pb.cc:250: undefined reference to `google::protobuf::Message::MaybeComputeUnknownFieldsSize(unsigned long, google::protobuf::internal::CachedSize*) const'
/tmp/go-link-96276495/000017.o: In function `example::Person::GetMetadata() const':
/my_project/example/hello.pb.cc:297: undefined reference to `google::protobuf::internal::AssignDescriptors(google::protobuf::internal::DescriptorTable const* (*)(), absl::lts_20220623::once_flag*, google::protobuf::Metadata const&)'
/tmp/go-link-96276495/000017.o: In function `example::Person::MergeImpl(google::protobuf::Message&, google::protobuf::Message const&)':
/my_project/example/hello.pb.cc:265: undefined reference to `google::protobuf::internal::LogMessage::~LogMessage()'
/tmp/go-link-96276495/000017.o: In function `example::Person::_InternalParse(char const*, google::protobuf::internal::ParseContext*) [clone .cold.25]':
/usr/local/include/google/protobuf/parse_context.h:228: undefined reference to `google::protobuf::internal::LogMessage::~LogMessage()'
/usr/local/include/google/protobuf/parse_context.h:231: undefined reference to `google::protobuf::internal::LogMessage::~LogMessage()'
/tmp/go-link-96276495/000017.o: In function `example::Person::~Person() [clone .cold.26]':
/my_project/example/hello.pb.cc:153: undefined reference to `google::protobuf::internal::LogMessage::~LogMessage()'
/tmp/go-link-96276495/000017.o: In function `example::Person::Person(google::protobuf::Arena*, bool) [clone .cold.27]':
/my_project/example/hello.pb.cc:143: undefined reference to `google::protobuf::internal::LogMessage::~LogMessage()'
/tmp/go-link-96276495/000017.o: In function `example::Person::Person(example::Person const&) [clone .cold.28]':
/usr/local/include/google/protobuf/message.h:245: undefined reference to `vtable for google::protobuf::Message'
/usr/local/include/google/protobuf/message.h:245: undefined reference to `google::protobuf::MessageLite::~MessageLite()'
/tmp/go-link-96276495/000017.o: In function `_GLOBAL__sub_I.00102_hello.pb.cc':
/my_project/example/hello.pb.cc:105: undefined reference to `google::protobuf::internal::AddDescriptorsRunner::AddDescriptorsRunner(google::protobuf::internal::DescriptorTable const*)'
/tmp/go-link-96276495/000017.o:(.data.rel.ro._ZTIN7example6PersonE[_ZTIN7example6PersonE]+0x10): undefined reference to `typeinfo for google::protobuf::Message'
/tmp/go-link-96276495/000017.o:(.data.rel.ro._ZTVN7example6PersonE[_ZTVN7example6PersonE]+0x20): undefined reference to `google::protobuf::Message::GetTypeName[abi:cxx11]() const'
/tmp/go-link-96276495/000017.o:(.data.rel.ro._ZTVN7example6PersonE[_ZTVN7example6PersonE]+0x40): undefined reference to `google::protobuf::Message::InitializationErrorString[abi:cxx11]() const'
/tmp/go-link-96276495/000017.o:(.data.rel.ro._ZTVN7example6PersonE[_ZTVN7example6PersonE]+0x48): undefined reference to `google::protobuf::Message::CheckTypeAndMergeFrom(google::protobuf::MessageLite const&)'
/tmp/go-link-96276495/000017.o:(.data.rel.ro._ZTVN7example6PersonE[_ZTVN7example6PersonE]+0x78): undefined reference to `google::protobuf::Message::MergeFrom(google::protobuf::Message const&)'
/tmp/go-link-96276495/000017.o:(.data.rel.ro._ZTVN7example6PersonE[_ZTVN7example6PersonE]+0x80): undefined reference to `google::protobuf::Message::SpaceUsedLong() const'
/tmp/go-link-96276495/000017.o:(.data.rel.ro+0x0): undefined reference to `google::protobuf::Message::CopyWithSourceCheck(google::protobuf::Message&, google::protobuf::Message const&)'
/tmp/go-link-96276495/000018.o: In function `example::handle_Person(example::Person&, unsigned char*)':
/my_project/example/hello.gen.cc:14: undefined reference to `dlopen'
/my_project/example/hello.gen.cc:25: undefined reference to `dlsym'
/my_project/example/hello.gen.cc:26: undefined reference to `dlerror'
/my_project/example/hello.gen.cc:29: undefined reference to `dlclose'
/my_project/example/hello.gen.cc:16: undefined reference to `dlerror'
collect2: error: ld returned 1 exit status
I have various things when trying to solve this problem but it feels like I'm missing a crucial step.