cpp: c++ uses swift (cpp interop) - Posted on Jun 4, 2024 - See https://www.swift.org/documentation/cxx-interop - Logs Home - d0017

cpp uses swift (cpp interop)

c++ uses swift (cpp interop)

Install swift

Get swift

Download swift from https://www.swift.org

Setup environment

Extract swift to system.

swift_dir=/swift
export PATH="${swift_dir}/bin:${PATH}"
export LD_LIBRARY_PATH="${swift_dir}/lib/swift/linux:${LD_LIBRARY_PATH}"
export LIBRARY_PATH="${swift_dir}/lib/swift/linux:${LIBRARY_PATH}"

Make swift c++ interface

File: swift_box.swift

class swift_box
{
	public func print()
	{
		Swift.print("Hello swift!")
	}
}

var box = swift_box()
box.print()

compile swift code to generate cpp interafce

swiftc \
	-frontend -typecheck \
	swift_box.swift \
	-module-name swift_interface \
	-cxx-interoperability-mode=default \
	-emit-clang-header-path \
	swift_face.hpp

Uses swift interface in cpp code

File: hello_swift.cpp

#include "swift_face.hpp"

int main()
{
}

compile cpp code

clang++ hello_swift.cpp -std=c++2b -lswiftCore -o hello_swift

Full cpp code

File: hello_swift.cpp

#include "swift_face.hpp"
#include <iostream>
#include <string>

int main()
{
	{
		if constexpr (swift::isUsableInGenericContext<unsigned int>)
		{
			std::cout << "unsigned int : true" << std::endl;
			auto metadata = swift::TypeMetadataTrait<unsigned int>::getTypeMetadata();
			std::cout << "metadata: " << *std::bit_cast<unsigned int *>(metadata) << std::endl;
		}
		else
		{
			std::cout << "unsigned int : false" << std::endl;
		}
		std::cout << std::endl;
	}
	{
		if constexpr (swift::isUsableInGenericContext<double>)
		{
			std::cout << "double : true" << std::endl;
			auto metadata = swift::TypeMetadataTrait<double>::getTypeMetadata();
			std::cout << "metadata: " << *std::bit_cast<double *>(metadata) << std::endl;
		}
		else
		{
			std::cout << "double : false" << std::endl;
		}
		std::cout << std::endl;
	}
	{
		if constexpr (swift::isUsableInGenericContext<std::string>)
		{
			std::cout << "std::string : true" << std::endl;
			auto metadata = swift::TypeMetadataTrait<std::string>::getTypeMetadata();
			std::cout << "metadata: " << *std::bit_cast<std::string *>(metadata) << std::endl;
		}
		else
		{
			std::cout << "std::string : false" << std::endl;
		}
		std::cout << std::endl;
	}
}

clang++ hello_swift.cpp -std=c++2b -lswiftCore -o hello_swift