Build Protobuf for Unreal Engine 5 C++ 20 on Windows

Build Protobuf for Unreal Engine 5 on Windows.md

Build Protobuf for Unreal Engine 5 C++ 20 on Windows

Prepare Environment

source code https://github.com/protocolbuffers/protobuf/commits/v27.2

Suppose we have the following file structure on D:

├── Code
│	├── protobuf
│	├── protobuf-build
│	├── protobuf-install

protobuf contains source code cloned from github

protobuf-build contains building config

protobuf-install contains our final headers and libs.

Build

first follow https://github.com/protocolbuffers/protobuf/blob/v27.2/cmake/README.md

cd protobuf-build
#-G "Visual Studio 17 2022" => means generate solution for vs2022
# -DCMAKE_CXX_STANDARD=20 => means use c++ 20
# Dprotobuf_MSVC_STATIC_RUNTIME=OFF => most important or won't work
# see https://stackoverflow.com/questions/47900268/statically-link-google-protobuf-lib-into-a-dll-library
cmake -S "..\\protobuf" -G "Visual Studio 17 2022"  -DCMAKE_INSTALL_PREFIX="D:\\Code\\protobuf-install\\Release" -DCMAKE_CXX_STANDARD=20 -Dprotobuf_MSVC_STATIC_RUNTIME=OFF -Dprotobuf_BUILD_TESTS=OFF  -DCMAKE_BUILD_TYPE=Release

open your file explorer go to protobuf folder,delete verify functions in the following files

• D:\Code\protobuf\third_party\abseil-cpp\absl\container\internal\btree.h
• D:\Code\protobuf\third_party\abseil-cpp\absl\container\internal\btree_container.h

Go to protobuf-build folder,open protobuf.sln,Right click INSTALL project under the folder CMakePredefinedTargets then chose build.

Use Protobuf in Unreal

Add a ThirdParty folder in your project under the Source folder. copy inlcude and lib from D:\Code\protobuf-install\Release to ThirdParty\google\protobuf\

Add config in you YourProject.Build.cs to add headers and libs

PublicIncludePaths.AddRange(new string[] {
	// change this to your path
	Path.Combine(ProjectPath, "ThirdParty/google/protobuf/include"),
});

// ADD .lib files in ThirdParty\google\protobuf\lib
foreach (var libFile in libFiles)
{
	PublicAdditionalLibraries.Add(Path.Combine(pb_path, libFile));
}

PublicDefinitions.Add("PROTOBUF_ENABLE_DEBUG_LOGGING_MAY_LEAK_PII=0");
PublicDefinitions.Add("PROTOBUF_BUILTIN_ATOMIC=0");

now if you start building your project,you will find several macro errors:

• Error C4668 PROTOBUF_BUILTIN_ATOMIC
• Error C4668 ABSL_INTERNAL_HAS_RTTI
• Error C4800 : from “const google::protobuf::OneofDescriptor *” to bool

for the first two erros, just assume PROTOBUF_BUILTIN_ATOMIC/ABSL_INTERNAL_HAS_RTTI are both 0 and delete the code between #if and #else to keep the code in the else branch

for the third error change code to return field->real_containing_oneof() == nullptr;

Now it should work!